Detailed guides to painful problems, treatments & more

The Complete Guide to Muscle Strains

Muscle strain (pulled muscle) and muscle pain explained and discussed in great detail, plus reviews of every imaginable treatment option, with lots of referencing

Paul Ingraham • 160m read
Photo of a young female runner with a muscle strain, sitting on a bright orange running track, holding her hamstring muscle, obviously in pain.

Muscle strains strike most often in the big muscles of the body. But sometimes the pain is not what it seems …

Muscle strain — a literally ripped muscle — is often extremely difficult to recover from. In 2012, Gene Lawrence, a 74-year-old weightlifter, tore his quads (and not while lifting). A doctor told him he’d never do a squat again. But Gene’s passion for his sport kept him going. And yet several months later he was on the verge of beating his personal records — a nearly total recovery.1

You can recover from nearly anything if you are patient and methodical.

But how patient, and what method? What is muscle injury, and how does it heal? What works? What doesn’t? And here’s a curve ball: is your muscle even actually physically damaged? Muscle strain and pain are usually woven together, and often pain alone is mistaken for injury. And there are some other kinds of injury that can mimic a strain (especially stress fractures in the pelvis).

This is an extremely detailed guide, regularly updated for almost twenty years (seriously). It thoroughly explores the science of injured and hurting muscle.

Muscle strain and pain myths and misconceptions

Believe it or not (and it does seem a bit ridiculous in 2023) muscle pain is still a subject of scientific mystery and many myths and misconceptions. A torn muscle is arguably among the most medically neglected of all common injuries.23 A major recent review couldn’t find enough evidence for conclusions about any of the most popular treatments4 — for an injury that affects the highest profile athletes in the world, playing sports that involve more resources than small nations. It’s a little surprising we’re not further along at this point in history.

“We can put a man on the moon, but … ”

And so, although most muscle pain is relatively simple to diagnose and self-treat, an incredible number of people seek treatment for muscle strains that have been misdiagnosed as something else … or they have “something else” that’s been misdiagnosed as a muscle strain. Strain, pain, spasm, contracture, scar tissue, tone, tension, and stiffness are all poorly understood and routinely confused. They are not only surprisingly complex topics scientifically, but clinicians are not generally aware of the research that has been done. Certainly family doctors are not competent to assess and treat musculoskeletal problems, including muscle strains.5

The world obviously needs more and better information about muscle pain.


So what is a muscle strain exactly?

A muscle “strain” is any physical trauma to muscle caused by force applied along the length of the muscle (tensile force). That force can be applied by contraction of the muscle itself (active strain), or imposed on it by a stretch (passive strain), but there’s no practical difference between those scenarios. There are other kinds of muscle injuries, and a surprising amount of confusion, even among professionals, about exactly what a “strain” means.6

A strain is also often called a “pulled muscle” or “muscle tear.” The word “pulled” is an odd misnomer, a synonym for spasm in many languages.8

Although you might have problems that make you vulnerable to a muscle strain, the direct cause of every muscle strain is traumatic ripping of the muscle tissue — arg! — usually at the point where the muscle meets its tendon. Muscle will tear under the force of your own muscular contraction, or excessive stretch.

The more muscle fibres are torn, the worse the strain. In the case of a serious strain, the entire muscle may completely rupture — literally ripped in half! Triple arg! (Total ruptures are serious injuries, much worse than partial ruptures.)

Muscle strains are particularly common in the thigh and groin in soccer, ultimate, hockey and other fast-moving team sports.

Muscle strains are particularly common in the thigh & groin in soccer, ultimate, hockey & other fast-moving team sports.

Obviously a muscle can also be bruised, crushed, or lacerated, but those are quite different and much more obvious traumas: the “contact” muscle injuries. This tutorial is mainly about non-contact strains, the kinds of strains that happen without colliding with anything or anyone. (“Why are you hitting yourself?”) There’s not much medical mystery involved in being gouged by a hockey skate. We also won’t discuss full muscle ruptures in much detail, because they are so extreme that they are easy to diagnose — even doctors can do it! 😉

It’s important to determine whether or not you actually have a muscle strain, or some other kind of muscle injury… because tearing is not the only invisible way to hurt a muscle. Physical injury does not have tidy borders. Surprisingly, there’s actually a major grey area between muscle that’s clearly physically damaged and much more subtle and cryptic kinds of muscle injury. That grey area is interesting, and it is this document’s raison d’être.


Part 2


How do you know that you’ve got a muscle strain?

Many people mistakenly think they have a torn muscle, because there are some common problems that feel like a muscle strain. These other problems can be seen as a different type or degree of muscle injury, and in fact they have even been formally classified that way.9 But such classifications are usually controversial the moment they are published, and other experts describe these more subtle muscle problems as just “muscle pain” without injury… because we clearly don’t understand exactly what’s wrong with the muscle (just its effect, pain).

True structural muscle strains — defined by visible fibre disruption — are actually surprisingly rare, compared to other causes of muscle pain. Funny thing about this tutorial: most people who find this document, like most people who think they have strained a muscle, have actually not done any such thing — or (just as common) they strained a muscle once upon a time, but the strain healed long ago and has since become an entirely different problem.

This could be you!

Some of the things that get confused with muscle strains are (and these will all be covered in more detail below):

True muscle strain checklist

Here’s a checklist of the signs and symptoms of a true pulled muscle. If you can say, “Yeah, that’s me,” to all of these, then congratulations: you probably have an actual, certifiable, card-carrying Muscle Strain® — that is, structural muscle damage.

If you “woke up with it,” or the pain came on slowly over several days, or if it’s six months old, or if the pain isn’t consistently in one particular place … then we’ll be talking about other possibilities. If your real problem is actually a painful “muscle knot,” for instance, you might want to take your knots for a nice massage — but massage is mostly pointless for a strain.


The “oh shit” moment: the most essential sign of muscle strain

Muscle strain cannot occur without an “oh shit” moment. In other words, it hits suddenly: you know that something nasty has happened, immediately and with perfect clarity. You feel wounded. In physical therapy, this is what we call a history of “sudden onset.”11

If your pain didn’t start suddenly (or very nearly so), it ain’t a muscle strain. Muscle strains are traumatic by nature, almost always occurring during intense athletic activity. The victim says a bad word, perhaps several of them in the case of a grade II injury. In the case of a grade III, there is generally screaming and falling down and probably turning a bit green.

And yet …

Rupture: not as obvious as you’d think!

Complete hamstring avulsions — that is, complete ruptures of muscles where they attach to bones — are not necessarily obvious. They aren’t all as painful initially as they sound (not a strong “oh shit” sign). And according to O’Laughlin et al, they “can be difficult to diagnose due to swelling and patient guarding, which may mask a visibly palpable defect and lead to delays in diagnosis.”12 Yikes!

In that case study, the only diagnosis was “hamstring pain” for several days, before the avulsion was finally confirmed by MRI, and surgically repaired on day 13. It’s not hard to imagine cases where the diagnosis would have taken much longer — too long.

So how would you know? Many of the other signs discussed here would be relatively obvious, especially substantial weakness. If the muscle is actually detached, obviously there will be a loss of strength. With some muscles, the loss is total or close to it.13 In the case of the hamstrings, there are other “strings” that can take over — which is another reason why a hamstring rupture is surprisingly hard to diagnose. The strength loss would be dramatic, probably about one third (because there are three hamstrings: the semitendinosus, semimembranosus, and biceps femoris), but it’s interesting how non-obvious that is.14 But anyone with a hamstring rupture is going to have a significant performance problem.


Cramp versus strain example: Multi-muscle cramping catastrophe on a hot summer night

Back in the late 2000s I was enjoying my athletic peak and just barely managing not to embarrass myself with younger and more talented athletes. One hot summer night I was running low on electrolytes: too much sweating, not enough salt intake. (Actually, that’s a surprising myth.15) I was playing “goaltie” (say it like goal-tea) a variant of ultimate: a hard-running Frisbee sport with the same intensity and speed as soccer, but with more jumping.

Both calves spasmed on a jump, bringing me down hard. That was nasty, but it was just the start: as soon as I hit the ground, both sets of hamstrings went off as well, and all that was more than enough to make for a good cramping story … but then my abdominals joined the fray, and that gave me an anecdote I’ll be sharing for the rest of my life.

The cramping all hurt, a lot, but I was too surprised and busy to focus on the pain. If you’ve ever had a strong spasm, you know that there’s a powerful instinct and need to elongate the muscles. Stretching is your only hope of relief. But I had a puzzle to solve: just try to stretch the backs of your legs and your abdominal muscles at the same time. It’s an anatomical impossibility.

Photograph of me playing ultimate, a sport that has caused many cramps and a few muscle strains over the years.

That’s me in the air at the back. Check out that vertical! It was that kind of jump that triggered a massive wave of spasms …

I jackknifed back and forth so violently that the other players wondered if I was having a seizure, but I was simply on my impossible mission to stretch both sides of my body. If I stretched my legs, the abdominals would bunch up; if I stretched my abdominals, then leg muscles tried to kill me! After about three tries each way, I realized it couldn’t be done and that my only hope was compromise: to find the least awful position somewhere between the extremes. It meant that neither muscle group would really be stretched at all — but neither would be allowed to fully contract either. I gasped “cramps! lots of cramps!” so everyone knew I wasn’t actually having a seizure … and then waited it out.

Without the power of stretch, the cramps took a long time to fade. It was a long time to endure extremely powerful contractions.

A spasm is capable of injuring muscle. In this case, I was wrenching back and forth, my own muscles in a tug-of-war with each other. These were perfect conditions for injury. Something had to give, and it did — I had mild strains of all the affected muscles, resulting in not just days of soreness but severe soreness for weeks, and a vulnerability to reinjury that was still a problem a full year later.

The spasm here was the strong involuntary contraction of the muscles. The strain was the injury caused by the forces on the muscles.


Location, location, location

Another way of knowing you’ve got a muscle strain is by the location. Muscle strains are much more common in some muscles than others. Every “groin pull” is a muscle strain of one or more of your hip adductors, for instance.

You can strain virtually any muscle in your body, but the commonly strained muscles are:

The pattern here is big muscles, which we tend to use for explosive or intense effort. However, a strain is possible in any muscle.

Even more specifically …

Strains often occur where muscles meet tendons, the myotendinous junction. Tendon is the shiny white “bio rope” that connects muscles to bones (in contrast to the bone-to-bone connections of ligaments). Tendons blend smoothly into muscles, like fingers of two types laced together, but at a cellular level. When a muscle contracts, the greatest strain naturally occurs where it pulls, which is of course where the tendon is. All the force converges on the tendon, but it’s not going to give. (In many cases, even bone will give way before tendon does!) Tendon has an extraordinary tensile strength, much greater than steel cable. Instead, the muscle tissue tends to fail close to where it becomes more tendon-y.

It can be hard to tell where this zone of likelihood is. For instance, in the hamstrings, the tendons are quite long and complex, and blend into the muscle along a considerable span. So you can have a myotendinous strain there that is basically right in the middle, between thigh and knee.


The hurtin’ and the weak

You can feel confident that you probably have a muscle strain when the contraction of one specific muscle feels both weak and painful. This is because strength is inhibited by more than just pain: the ability of the muscle to contract has been physically disrupted.

Strength/pain combinations are diagnostically informative, and a good physical therapist is always looking for such combinations when assessing your case. A “weak and painful” contraction test tends to indicate muscle strain. “Strong and painful” means something else. “Weak and painless” something else again.

The strong-but-painful category of possibilities is large and diverse, but dominated by tendinitis, which is sometimes mistaken for a muscle strain. But tendinitis will not cause significant weakness. The pain might make you hesitant to pull on the tendon, but the muscle can still do it: so the contraction will be strong-but-ouchy.

Painless-but-weak is an even bigger diagnostic category, and I’ve included it here mainly to say what it does not indicate, rather than what it does indicate.16 Strains are mostly not painless, and a completely painless strain is probably impossible. Therefore, if your muscle contraction is painless, you probably don’t have a strain. (Note that if you have really any pain at all, that doesn’t quite count as painless in the “weak and painless” combo.)

There is an exception (because of course there is): some strains cause so much “inhibition” — neurological shutdown of contraction — that you are simply unable to use the muscle enough to be painful. The inhibition is actually preventing you from hurting yourself. This is most likely to occur with more severe strains, but people are quirky; I haven’t seen any clear examples in practice that I can recall, but I bet they exist.

Ligament sprains, for a contrasting example, do not cause weakness or pain with muscle contraction alone, because ligaments just hold joints together and muscle contraction mostly does not directly pull on them — it just moves the joint they are attached to, which might hurt a little. So if you just clench your muscles in place, without moving (isometric contraction), and nothing hurts (much) … that could be a ligament sprain: strong and largely painless contraction.

Photograph of an ankle being taped with a compression bandage for a sprain.

Is this a sprain or a strain?

Definitely a sprain. Stabilizing a joint like this is for sprained ligaments, not strained muscles. Sprains always occur at joints, especially the ankles, knees & wrists.

This is more about guidelines than rules: contraction of a strained muscle probably isn’t weak and totally painless, and probably isn’t strong and painful. Muscles strains mainly make muscle contractions weak and painful, but there are undoubtedly a few exceptions, as there are with anything in medicine.


Could you have a muscle spasm instead of a strain?

You sure could! Spasms, cramps and “charlie horses” can both seem like a muscle strain and they can also actually cause one…


Purchase full access to this tutorial for USD$1995. Continue reading this page immediately after purchase. See a complete table of contents below. Most content on is free.?

Almost everything on this website is free: about 80% of the site by wordcount, or 95% of the bigger pages. This page is only one of a few big ones that have a price tag. There are also hundreds of free articles. Book sales — over 72,700 since 2007?This is a tough number for anyone to audit, because my customer database is completely private and highly secure. But if a regulatory agency ever said “show us your math,” I certainly could! This count is automatically updated once every day or two, and rounded down to the nearest 100. Due to some oddities in technology over the years, it’s probably a bit of an underestimate. — keep the lights on and allow me to publish everything else (without ads).

Q. Ack, what’s with that surprise price tag?!

A. I know it can make a poor impression, but I have to make a living and this is the best way I’ve found to keep the lights on here.

Logos for Visa, Mastercard, and Amex.

Paying in your own (non-USD) currency is always cheaper! My prices are set slightly lower than current exchange rates, but most cards charge extra for conversion.

Example: as a Canadian, if I pay $19.95 USD, my credit card converts it at a high rate and charges me $26.58 CAD. But if I select Canadian dollars here, I pay only $24.95 CAD.

Why so different? If you pay in United States dollars (USD), your credit card will convert the USD price to your card’s native currency, but the card companies often charge too much for conversion — it’s a way for them to make a little extra money, of course. So I offer my customers prices converted at slightly better than the current rate.

read on any device, no passwords
refund at any time, in a week or a year
call 778-968-0930 for purchase help
ID  Vendor Information
owner Paul Ingraham
contact 778-968-0930
refunds 100%, no time limit +Customers are welcome to ask for a refund months after purchase — I understand that it can take time to decide if information like this was worth the price for you.
more info policies page
Logos for Visa, Mastercard, and Amex.

Paying in your own (non-USD) currency is always cheaper! My prices are set slightly lower than current exchange rates, but most cards charge extra for conversion.

Example: as a Canadian, if I pay $19.95 USD, my credit card converts it at a high rate and charges me $26.58 CAD. But if I select Canadian dollars here, I pay only $24.95 CAD.

Why so different? If you pay in United States dollars (USD), your credit card will convert the USD price to your card’s native currency, but the card companies often charge too much for conversion — it’s a way for them to make a little extra money, of course. So I offer my customers prices converted at slightly better than the current rate.

read on any device, no passwords
refund at any time, in a week or a year
call 778-968-0930 for purchase help

How can you trust this information?

I apply a MythBusters approach to health care (without explosives): I have fun questioning everything. I don’t claim to have The Answer for muscle strain and pain. When I don’t know, I admit it. I read scientific journals, I explain the science behind key points (there are more than 110 footnotes here, drawn from a huge bibliography), and I always link to my sources.

For instance, there’s good evidence that educational tutorials are actually effective medicine for pain.?Dear BF, Gandy M, Karin E, et al. The Pain Course: A Randomised Controlled Trial Examining an Internet-Delivered Pain Management Program when Provided with Different Levels of Clinician Support. Pain. 2015 May. PubMed 26039902 ❐ Researchers tested a series of web-based pain management tutorials on a group of adults with chronic pain. They all experienced reductions in disability, anxiety, and average pain levels at the end of the eight week experiment as well as three months down the line. The authors concluded: “While face-to-face pain management programs are important, many adults with chronic pain can benefit from programs delivered via the internet, and many of them do not need a lot of contact with a clinician in order to benefit.” Good information is good medicine!

So all the science and all the options for muscle strain treatment are here. If you’ve been struggling with pulled muscle injury, I think this tutorial will feel like a “good find” to you!

As with all the tutorials on, I’ve worked hard to provide you with the best information available anywhere — not just better researched and referenced, but also regularly updated, and presented in a clear, friendly style that’s just like coming to my office and having a nice long conversation about it, where all your questions get answered. But at a fraction of the cost.

Logos for Visa, Mastercard, and Amex.

Paying in your own (non-USD) currency is always cheaper! My prices are set slightly lower than current exchange rates, but most cards charge extra for conversion.

Example: as a Canadian, if I pay $19.95 USD, my credit card converts it at a high rate and charges me $26.58 CAD. But if I select Canadian dollars here, I pay only $24.95 CAD.

Why so different? If you pay in United States dollars (USD), your credit card will convert the USD price to your card’s native currency, but the card companies often charge too much for conversion — it’s a way for them to make a little extra money, of course. So I offer my customers prices converted at slightly better than the current rate.

read on any device, no passwords
refund at any time, in a week or a year
call 778-968-0930 for purchase help

Muscle Strain Causes

Assuming you have a muscle strain — and not trigger points or DOMS or a spasm or a small purple monster stabbing you in the back — then it’s time to discuss how it happened.

A strain really is a rip. Muscle is made up of fibres, bound together in “fractal sausage wrappings.” If enough force is applied to them, those fibres and wrappings tear just like anything if you pull on it hard enough. There are three kinds of situations where muscle tends to tear:

  1. by stretching it too far yourself
  2. by being forced into a stretch too quickly or too far
  3. by contracting hard against strong resistance

The third scenario is the most common in sports. Such strains usually happen at moments when the muscle would normally elongate to allow a movement, but is also contracting to control or limit elongation. Sometimes the muscle just isn’t strong enough to hold up under these opposing forces, or perhaps the opposing forces are slightly unbalanced and/or at odds with momentum — and something has to give.

This “contracting while lengthening” strangeness is called an “eccentric” contraction in physio-speak. You could tear your biceps by exerting yourself too intensely to resist the descent of the barbell, for instance. Most such muscle tears occur during fast eccentric contractions. They are common in sprinters, for instance.

Technically, the muscle is doing what it is “supposed” to do. Eccentric contractions are a normal part of the action, and sometimes the forces involved are simply too great. Another view, however, is that injury occurs only when the muscle action is poorly coordinated.

Logos for Visa, Mastercard, and Amex.

Paying in your own (non-USD) currency is always cheaper! My prices are set slightly lower than current exchange rates, but most cards charge extra for conversion.

Example: as a Canadian, if I pay $19.95 USD, my credit card converts it at a high rate and charges me $26.58 CAD. But if I select Canadian dollars here, I pay only $24.95 CAD.

Why so different? If you pay in United States dollars (USD), your credit card will convert the USD price to your card’s native currency, but the card companies often charge too much for conversion — it’s a way for them to make a little extra money, of course. So I offer my customers prices converted at slightly better than the current rate.

read on any device, no passwords
refund at any time, in a week or a year
call 778-968-0930 for purchase help

Muscle Strain Treatment

You can do a few things that may improve recovery time and completeness, or at least reduce pain along the way. I will also explain some of the basics of self-treating your trigger points, because they often complicate muscle strain healing.

But it’s important to bear in mind that there are essentially no proven treatments for muscle strain — that is, nothing that definitely speeds healing along, makes it more complete, or eliminates complications. A large 2017 scientific review by Ramos et al concluded that “the evidence of the effectiveness of these modalities in muscle injuries is not fully established due to the little scientific research on the topic.” They were referring to cryotherapy, laser therapy, therapeutic ultrasound, therapeutic exercise, and manual therapy, and I will get further into most of these.

The absence of evidence doesn’t mean that nothing works — just that none of the options have really been studied well enough to actually know. Speculation is unavoidable. In many ways, this book is not about “what works,” but about how to make educated guesses about what things are the most worth trying: the safest, the cheapest, the most practical and plausible. Here’s a quick summary of all the options, roughly in order of most promising to least:

And there are some treatment approaches that I am so skeptical of that I recommend avoiding:

Continue reading much, much more…

Logos for Visa, Mastercard, and Amex.

Paying in your own (non-USD) currency is always cheaper! My prices are set slightly lower than current exchange rates, but most cards charge extra for conversion.

Example: as a Canadian, if I pay $19.95 USD, my credit card converts it at a high rate and charges me $26.58 CAD. But if I select Canadian dollars here, I pay only $24.95 CAD.

Why so different? If you pay in United States dollars (USD), your credit card will convert the USD price to your card’s native currency, but the card companies often charge too much for conversion — it’s a way for them to make a little extra money, of course. So I offer my customers prices converted at slightly better than the current rate.

read on any device, no passwords
refund at any time, in a week or a year
call 778-968-0930 for purchase help

Cramps that injure

A spasm is a sustained, excessive contraction of an entire muscle,17 or possibly of a group of muscles.

A cramp or “charlie horse” is just a particularly violent spasm, quick and strong. The most common kinds of spasms and cramps occur in the calf or arch muscles of the foot at night, or in exhausted muscles, or in a big muscle group like the quadriceps after getting traumatized in some way. And a strong enough charlie horse can also actually tear a muscle. So, for instance, a rugby player having a bad day might get whomped in the quadriceps, causing a severe contusion (bruise), and then a reactive cramp… which in turn causes a muscle strain.

However, a cramp has to actually start ripping your muscle fibres to cause a strain, and that is probably not a common scenario.

People recover from most cramps quickly. A bad cramp might feel like it must have caused a bit of a strain… but if it only lasts for a day or two, that means that no significant damage could possibly have been done. On the other hand, if you have a cramp and you’re in pain for many days… some damage probably was done.

Spasms that cause ongoing pain that could be mistaken for a strain that is healing poorly

An acute, powerful, painful spasm in a big muscle is the most dramatic example of a whole family of diverse unwanted muscle contractions. The physiology and neurology of regulating muscle tone and contraction is dazzlingly complex and can fail in many ways. There are many problems that cause more contraction than we need or want — cramps, dystonia, fasciculations, and myokemia, etc — and I explore all of those in the article Cramps, Spasms, Tremors & Twitches: The biology and treatment of unwanted muscle contractions.

Only big cramps have the potential to actually damage muscle as far as anyone knows. But all those other types of dysregulated contraction may have the potential to cause pain that feels like a muscle injury. This basic dilemma — is it a strain, or does it just feel like one? — is one of the central questions of this book. And, unfortunately, it’s closely related to one of the toughest questions in all of musculoskeletal medicine: can non-obvious spasms hurt? Can you have a spasm that isn’t obviously a spasm but is enough of a spasm to be painful?

No one really has a good answer to this. I think “maybe” is the only honest answer. Curiously, not all spasms are painful, and we don’t actually know why they hurt when they do.18

So not all spasms are painful, but if you have one, it’s probably a painful one (or you wouldn’t be reading this). They probably can feel like an injury that isn’t healing well. Many people who believe they have a “strain” could have a muscle that was never acutely injured, but is contracting uncomfortably.

The idea that back pain can be caused by spasms is almost universally accepted, even though it’s not scientifically clear that painfully contracting back muscles are actually the cause of any back pain. It’s more likely that they are clenching protectively, both to limit movement in general, and (more dramatically) to stop you from moving in a dangerous way, like yanking a kid away from a drop-off. The cramping itself is probably not what hurts — the pain could just be a sensory alarm that goes with it. (This topic is discussed more in the cramping article mentioned above, and in great detail in my low back pain book.)

And yet we also know that some types of pathological cramps are indeed both non-obvious and cause great suffering. A classic example is the “multiple sclerosis hug,” which involves chronic spasm of many muscles around the ribcage. To the patient, it feels like being suffocated by a boa constrictor, but not really like a “cramp” — there are too many small muscles involved.

So there probably are ways for muscle to feel injured without being injured. One of the major hypotheses is the slippery concept of the micro-cramp or “muscle knot” or “trigger point.” The next few sections are all devoted to this contentious but fascinating idea.


Could you have muscle “knots” instead of a muscle strain?

This is the most important chapter of this guide, and I think it gets really interesting. (For muscle physiology dorks at least.)

The muscle injury classification system defined by Mueller-Wohlfahrt et al in 2013 divides muscle injury into three kinds of injuries: functional, neuromuscular, and structural injuries. DOMS is the first example of a “functional” muscle injury I’ve discussed: the muscle is clearly messed up in a way that is clearly recognizable, but there’s literally nothing visibly wrong with the muscle, not even on a microscope.

But then there’s also “fatigue-induced muscle disorder,” which isn’t DOMS but it isn’t a structural strain either. So, er… what is it? They don’t know, and all they do is dip their toe into the topic and mention a few ideas that barely scratch the surface. Many books have been written about what might be going on with muscles that are feeling and acting hurt but don’t look obviously hurt under a microscope.

And this is one of those books. Or rather, this book comes with one of those books (the other volume of this pair). It’s devoted to the phenomenon of muscle “injury” that cannot be objectively diagnosed and yet clearly exists.

Other experts immediately responded to the idea of “functional” muscle injuries by pointing out that “it is possible that ‘functional’ lesions may in fact represent yet-to-be understood ‘structural’ pathology.”19 Amen! Just because we can’t see it easily doesn’t mean it’s not there. Almost everything interesting in biology happens at the astonishingly small scales of biochemistry. Even DOMS — such a familiar, ordinary-seeming problem — is incredibly hard to objectively diagnose, because it involves only some very specific and ephemeral biomarkers. Like tracking fireflies from a thousand kilometres away.

“Muscle knots” is one common label for the clinical manifestation of presumed structural pathology, for whatever it is that goes wrong with muscle. Slightly more formally, they are known as “trigger points,” and a chronic problem with lots of bad ones is often called “myofascial pain syndrome.”

Basically we’re just talking about sore spots that hurt when you press on them, or try to use them — so a lot like a minor little muscle strain. Except they can be surprisingly non-minor for something you can’t easily verify with a muscle biopsy.

It’s so common for trigger points to be misdiagnosed as muscle strain that it is certainly the most common of all the many trigger point misdiagnoses, and possibly — yes, possibly — it is the most common misdiagnosis in all creation. So sad. Most people who think they have a muscle strain actually have muscle knots. Seriously. Odds are good that this means you. As mentioned above, I warned you that you might have the wrong book! But, fortunately, you also have the right book in that case.


What is a muscle knot? And how is it different than spasm and strain?

A muscle knot, technically known as a trigger point, is a small section of a muscle that is in spasm. A micro-cramp. That is only an analogy, though: it is a fundamentally different phenomenon, and poorly understood. In fact, the micro-cramp idea is quite controversial. As previously mentioned, it is not scientifically clear that cramping can be both painful and subtle at the same time.

It is also different than a strain. In a strain, the muscle tissue is clearly (visibly) damaged, a “structural” injury. In a trigger point, the muscle hurts — it may even hurt more than a strain — but it is not clearly damaged tissue. It is more of a painful muscle “sickness,” and not so much an injury.

If you’ve got a lot of trigger points, you have what we call “myofascial pain syndrome.” But you are in good company! Many, many people have enough trigger points to qualify. Muscle knots are an almost normal feature of muscles. It’s like skin and pimples — everyone gets a painful trigger point sooner or later, and some of us are unlucky and tend to get more of them. But in the worst cases, things can really get ugly.

Muscle knots are strongly implicated in many other cases of undiagnosed aches and pains, especially headaches and neck pain and back pain, and are probably the genuine explanation for many alleged “injuries,” such as muscle strains and repetitive strain injuries (RSIs) like carpal tunnel syndrome.

Although mild and moderate cases are easily treated, it is unknown to many medical professionals, and unfamiliar to most of them. But registered massage therapists often recognize and treat this condition because of our extensive hands-on experience20 — it is most easily diagnosed by feel.

This may all be sounding a little bit crazy, almost like some kind of conspiracy theory. But even though most doctors are uneducated about trigger points, they are not a pseudoscientific diagnosis. The phenomenon is well-known and not questioned by anyone — sore spots associated with pain and stiffness are definitely a thing — but the explanation is a controversial mess. They have been studied by medical researchers quite a bit, but not enough or well enough yet. They have even been photographed and studied with biopsy and electromyography — with the right, advanced tools they actually can be “visually” identified.

Note that it’s also possible that trigger points have a non-cramp explanation, and can still feel like an injury without being any kind of cramp.


Referred pain from trigger points

One of the secrets to the clinical importance of trigger points is a phenomenon called “referred pain.” When the insides of muscles hurt, the nervous system gets “confused” about where the symptoms are coming from — we did not evolve with nervous systems capable of precisely locating the source of internal pain. So instead of feeling just the knot, we often feel aching sensations throughout a whole region, and not necessarily even where the trigger point is.

Referred pain tends to occur in characteristic patterns which are amazingly consistent from one person to the next. When people tell me that they get their headaches “behind the eyes,” I can show them a chart of the referred pain pattern that causes them so much misery. When I press on a common trigger point in the back of the shoulder and casually mention that it may cause pain in the elbow, clients are impressed. “How did you know that?” they usually ask.

“Ancient Caucasian secret,” I tell them. “I looked it up in a textbook!” Common referred pain patterns from trigger points were first published in 1953, and later in more detail.21

So trigger points can feel painful right where they are, or they can cause pain to spread out in interesting and sometimes alarming ways, causing entire limbs to ache, to feel heavy and dead, or to tingle and buzz as if there is “some kind of nerve problem” (which there usually isn’t). These sorts of sensations are almost invariably the kind of thing that generally cause confusion, misdiagnosis, and anxiety.


So how do you tell the difference between muscle strains and knots?

Some muscle knots can come on fast, in exactly the same circumstances as a muscle strain would occur. They can feel lumpy, just like the tear in a strained muscle. They can make the muscle weak and painful, just like a strained muscle, and the worst knots can make it just as weak and painful as the worst strains (excepting complete ruptures — nothing is weaker than a completely ruptured muscle).

Fortunately, it’s rare for a knot to have all of these strain-imitating features. And there are several common differences. Here’s your checklist for knots:

  • Do you have a “dead/heavy” feeling around or near the pain? Not exactly numb (you can feel a pinprick), but sort of?
  • Has your pain been going on for more than a few weeks, or coming and going for that long, without really getting much better? (There is a section below about estimating healing time.)
  • Is your pain location ever hard to identify? Does it “spread”?
  • Does it often hurt even when you’re not contracting the muscle?
  • Did the symptoms start slowly, or erratically, instead of with an obvious injury? Did you wake up with it one morning? Have you been trying to figure out what you did to yourself the day before?

If you have more than a couple of these, you probably have muscle knots instead of a strain, or at least muscle knots with a strain.


Muscle strains that don’t heal have usually been hijacked by trigger points

Boy, as if this weren’t complicated enough: it’s common for muscle strain and muscle knots to co-exist. That’s right, most people who get a strain also have trigger points.

Here are the two typical scenarios:

  • You start with muscle knots. This makes your muscles dysfunctional, which probably predisposes you to a muscle strain.22 Then you get a muscle strain to go with your knots. The strain heals, but it’s hard to tell, because the muscle was rotten with knots before, and it’s still rotten with knots after.
  • You start with healthy muscles. But then you get a muscle strain. The muscle strain heals, but meanwhile the injury aggravates the region and causes the formation of several nasty knots. Soon, the muscle strain is the least of your worries, because it has been replaced by muscle knots, which tend to be much more persistent. Except to you it just feels like a muscle strain.

Two kinds of hurt

First the pain of an muscle strain (the frying pan) & then the pain of seriously irritated muscle tissue throughout the region (the fire).

As you can imagine, there are many stages at which the two kinds of problems can be quite blurred together. I often see soccer players, say, who have had “some kind of groin pull” for the last eight weeks. It’s obvious — to me — that they are almost certainly suffering from both muscle strain and trigger points. It is the complexity of their symptoms that gives it away. A pure strain is pretty straightforward: it hurts when the muscle contracts, period. It slowly fades over time (if it doesn’t get hijacked by muscle knots.)

In addition to seeing countless cases like this as a hands-on professional, I also have considerable personal experience with this problem.

In the summer of 2008, I seriously injured my shoulder. I tried to stop someone else from catching a Frisbee and things went badly. I was playing ultimate (previously mentioned; the sport has wounded me many times). I leapt high in the air, tumbled clear over the other player who was catching the disc, and fell a couple of feet onto the tip of my shoulder … tearing my ligaments (an acromioclavicular joint sprain). It was a nasty injury. Unfortunately, months later, I was in more pain than ever.

Incredibly, I was actually fooled by the persistence of pain. I thought the injury wasn’t healing. Ironically, after years of teaching this principle to my own patients, I failed to recognize that I had jumped out of the frying pan of injury and into the fire of trigger points!

The story of my recovery perfectly illustrates this fascinating principle of injury healing. For readers who are injured, please read about it — I can’t think of a better way for you to discover how this works.

I tell that story of mine here: Muscle Pain as an Injury Complication: The story of how I finally “miraculously” recovered from the pain of a serious shoulder injury, long after the injury itself had healed.


Could you just have post-exercise soreness instead of a muscle strain?

You sure could. Sometimes people come to me with nasty delayed-onset muscle soreness (DOMS), also called post-exercise muscle soreness, thinking that they have strained something. It’s an understandable mistake. DOMS has been classified as a type of muscle injury.23 It sure can feel that way when it’s bad!

DOMS is that distinctive muscle pain that everyone experiences after intense or unfamiliar exercise. Weakness is a symptom as much as pain is — another reason it can be confused with muscle strain — but only hardened competitors are likely to test their strength while feeling so sore. The nastiness starts slowly during the hours after exercising, is often much worse the next morning, and then may continue to increase for another miserable 24 to 48 hours. Generally speaking, the longer it takes to peak, the longer it will take to recover — perhaps another three days at the worst. Some people find that the second day after exercising is much worse, while some don’t even notice DOMS until the second day.

For all its yuckiness, there are three blazingly obvious differences between DOMS and a muscle strain:

  • DOMS doesn’t start suddenly.
  • DOMS is always more widespread, and causes the entire muscle to feel tender to the touch.
  • DOMS goes away much more quickly.

Unfortunately, medical science cannot explain DOMS or prevent DOMS — there is literally not one single thing you can do to get rid of it or reduce it. It seems to be nature’s little tax on exercise, which everyone must pay. For more information about all that, see A Deep Dive into Delayed-Onset Muscle Soreness. (That’s a free article, that one — 98% of the 234 articles on are free.)


Diagnostic imaging

For difficult cases, there’s a lot to be said for taking a closer look — either confirming the diagnosis of strain, or eliminating other concerns.

Muscle strain’s primary symptom is pain in a specific spot or area of muscle tissue… but there are other conditions that can cause pain like that. For instance, groin or high thigh pain in athletes is often a muscle strain, but not always. If it’s just not getting better (or actually getting worse), it could also be a femoral or pelvic stress fracture — especially in women, but sometimes in men as well.

Some stress fractures, especially in the hip, are devilishly good at mimicking common muscle strains, especially in runners, and one of the strongest clues is pain that surges with weight-bearing. If bearing weight is unbearable, think stress fracture.24 But by far the simplest way to eliminate a fracture? Just take a peak inside with the magic machines! Magnetic resonance imaging (MRI is very “sensitive” and “specific” for signs of stress fractures: if it shows one, it’s definitely for real; if not, it’s probably doesn’t exist.25 Bone scintigraphy is out because of “low specificity, high dosage of ionizing radiation, and other limitations.”26 And X-ray isn’t great for stress fractures: it tends to miss them in the early stages.

The two main types of diagnostic imaging useful for diagnosing muscle strains are ultrasound and MRI.

Diagnostic ultrasound (making pictures with sound waves) is a very different beast than therapeutic ultrasound (trying to fix tissues by vibrating them with sound), and classic ultrasound is notoriously futile despite its popularity.27 But diagnostic ultrasound works brilliantly for many things, and is an invaluable diagnostic tool in many clinical situations.

Plus it’s cheap like borscht. As medical procedures go.

But ultrasound’s usefulness in confirming a strain diagnosis is a bit weak, unfortunately. It’s far from guaranteed that it can actually do the job at all. Some strains undoubtedly shine clearly on ultrasound, others not so much. It’s surprisingly complex. Here are some technical examples of the kinds of things that an expert would look for,28 quoted only to emphasize the complexity of the challenge:

Imaging findings in muscle injury range from intrafascicular and interfascicular muscle edema, blurring of fascicular margins, distortion of pennation angle, localized muscle fascicle discontinuity through to more extensive multi-fascicular discontinuity.

And you’ve got to tease all of that out of low-contrast, fuzzy black and white images. So not exactly an exact science. No imaging never has been.

A 2014 study found that ultrasound detected only 27% of soleus muscle injuries confirmed by MRI and “no injury was detected by ultrasound alone.”29 Not exactly encouraging.

Ultrasound is never required to diagnose a strain — it’s just not good enough at it. And a strain certainly should be diagnosable just from clinical signs and symptoms. That said, “should” isn’t always what it should be, and it’s not actually a terrible idea to do ultrasound to look for signs of a strain in cases where it’s more ambiguous. More information is often useful in tricky cases, and ultrasound is recommended by some experts.30 If nothing else, it can help to eliminate other unpleasant surprises like cysts and tumours, which always have to be considered in any case of chronic pain.

MRI: not perfect, probably better, a lot more expensive

MRI is both more effective for this purpose but also more expensive, much more. For tough cases, it seems worth considering if you can afford it, and if there’s any specific justification for it (like unusually stubborn pain with some symptoms that make the strain diagnosis questionable). For those who can’t afford it, don’t lose much sleep over it: it produces supplementary diagnostic information, not critical. It’s rarely going to be the only way to confirm or eliminate a strain diagnosis, and maybe never.


Part 3


What caused your muscle strain?

Assuming you have a muscle strain — and not trigger points or DOMS or a spasm or a small purple monster stabbing you in the back — then it’s time to discuss how it happened.

A strain really is a rip. Muscle is made up of fibres, bound together in “fractal sausage wrappings.”32 If enough force is applied to them, those fibres and wrappings tear just like anything if you pull on it hard enough. There are three kinds of situations where muscle tends to tear:

  1. by stretching it too far yourself
  2. by being forced into a stretch too quickly or too far
  3. by contracting hard against strong resistance

The third scenario is the most common in sports. Such strains usually happen at moments when the muscle would normally elongate to allow a movement, but is also contracting to control or limit elongation. Sometimes the muscle just isn’t strong enough to hold up under these opposing forces. Something has to give.

This “contracting while lengthening” is called an “eccentric” contraction in physio-speak.33 You could tear your biceps by exerting yourself too intensely to resist the descent of the barbell, for instance. But most such muscle tears occur during fast, intense eccentric contractions.343536 They are common in sprinters, for instance.

Technically, the muscle is doing what it is “supposed” to do. Eccentric contractions are a normal part of the action, and sometimes the forces involved are simply too great. Another view, however, is that injury occurs only when the muscle action is poorly coordinated

Zigging when you should have zagged

You could certainly make a case that the body should “know” not to contract too hard while the muscle is lengthening — in fact, there are sensitive reflexes designed to prevent exactly this, in theory. And therefore any failure of that system could be viewed as clumsy or uncoordinated muscle action. I call it “zigging when you should have zagged,” contracting a split second too early or slightly too much.

This strongly implies that a good warm-up may be an important part of athletic activity. Being metabolically and neurologically stimulated and responsive — ready for action — is probably a key method of prevention of muscle strains. Until recently, there wasn’t much research to prove this point. Fortunately, we now have the data showing that warmups do significantly reduce injury rates. This will be discussed more below in Prevention: Warmups work.

It’s also possible to strain a muscle simply by over-stretching it, with no contraction involved at all. This is uncommon, because a relaxed muscle has to be stretched awfully hard to tear it, but it certainly can happen.


The dancer’s strain (straining by stretch)

You don’t have to be moving fast to get a nice muscle strain. It can happen during strong stretching as well, with no contraction involved at all. A 2006 article in the British Journal of Sports Medicine compared muscle strains in sprinters and dancers: every one of 15 dancers “were injured while performing slow stretching type exercises.”37 So you really can just pull too hard on a muscle, ripping it like a piece of dough!

What could possibly go wrong? Dancers, gymnasts, martial artists & other athletes that often stretch vigorously may cause more injuries than they prevent.

Personally, I have seen many muscle strains from over-stretching in yoga classes. So this introduces an interesting side-note: stretching absolutely can be hazardous, in addition to being of questionable value unless you are a professional dancer or you are a contortionist for Cirque du Soleil. See Quite a Stretch to read all about why a stretching habit is probably not important for the average person, because it simply doesn’t have the benefits that most people give it credit for.

Do these types of strains occur more in people who have not warmed up? Is it possible that they wouldn’t have torn their muscle if their muscle had been warmer or more relaxed when they started? We can only speculate, because the research has simply not been done. But it certainly seems plausible.


What’s the worst-case scenario for your muscle strain?

Muscle strains occur in three grades of severity — I, II, and III — ranging from damaging or rupturing only a few muscle fibres, all the way up to tearing the muscle into two pieces. Yikes.

Muscle Strain Grading
GradeDescriptionHealing Time
Grade I Overstretching of a few muscle fibres with less then 10% percent fiber tearing and no palpable defect in the muscle. Rarely causes a bruise.2–8 weeks
Grade II 0–50% of the fibres torn, and a palpable defect in the muscle belly. Clear bruising.2–4 months
Grade III (rupture) 50% or more fibres torn, up to and including complete rupture of the muscle. Very large palpable deformation of the muscle, severe bruising, and no possibility of normal contraction in the acute phase.4–12 months

It takes a lot of tearing inside a muscle to make a bruising appear on the surface. A first degree strain is unlikely to show any bruising, but a second degree will usually look black and blue by the second day.

Even a Grade I strain can hurt quite a lot. I’ve seen plenty of tough guys pretty much convinced that they’ve ripped a muscle up but good — but they have no bruising, they actually can contract the muscle, and there’s not even any damage that you could feel. If you can use the muscle at all, it’s really not a grade III strain … even if it feels like it!

Straining a muscle that’s been strained before is particularly bad news — it takes quite a bit longer to recover. The next section helps you figure out just how long.


Timing tips: when is it safe to use a torn muscle again?

It’s hard to know exactly how long it’s going to take to heal from a strain for a couple reasons:

First, trigger points and other complications are common and they interfere with and prolong healing in unpredictable ways. Particularly in the last stages of healing, things may seem to drag on due to the presence of trigger points, and it’s often hard to be sure whether the injury itself is still healing, or you are just suffering from some persistent consequences of the injury.

Second, what feels “healed” to a couch potato would probably still be keeping a soccer player out of the game. You can feel mostly fine, and still be weeks away from being able to tolerate competitive intensity. Like a rope with a nick in it, the muscle may be strong enough to hold a 10 kilogram weight all day, but will give way in moments to a 150kg pull. If you demand maximum performance from your damaged muscle, obviously it may be longer before it feels like you are one hundred percent. Someone with only modest needs for muscular contraction may be “good to go” in half the time. So what is “enough time” depends as much on your life and your needs as it does on the injury itself. Tricky.

Despite that trickiness, most people who actually care enough to think carefully about healing time are usually also concerned about their athletic performance. So this section is mostly about that specific problem: “When exactly should I try to run/jump/play again?” And that simplifies things. For grade I and II strains — by far the most common, of course — there are some good tricks for estimating how long your muscle strain “should” heal to allow a return to most typical athletic activity. Assuming a leg injury for an example …

Method 1: Days of limping = weeks of recovery needed

How many days before you can walk mostly pain free? If it takes more than a day, the evidence shows that you’ll need at least 2 weeks.38 From that hard data, we can make a nice little rough rule of thumb: add about another week of recovery for every day of pain after that.

Days of limping Weeks of recovery
1 day 1 week
2 days 2 weeks
3 days 3 weeks

And so on. That pattern is probably a fairly good estimate up to about 5 weeks.

Method 2: Lost range of motion = weeks of recovery needed

Another decent data-based predictor of recovery time is range of motion: the more your range of motion is impaired, the worse the injury, and the longer you should take for recovery. The correlation between the two is strong. With a hamstring injury, if you lose more than approximately one third of your range of motion (compared to the uninjured side), you’re looking at six weeks minimum recovery time. At the other extreme, if your deficit is less than 10% — only a few degrees of knee range lost to a hamstring injury — you will probably be back to normal within a week or two.39

We can extrapolate from this to make a rule of thumb for any muscle. In the study cited, they found long recovery times with more than 30˚ ROM deficits in a joint that could (from the reference point they used) extend up to 90˚. Let’s simplify, round-up a bit, and say that losing half the healthy range of joint to a strain is roughly the worst-case scenario…

% deficit Weeks of recovery
10% 2 weeks
30% 4 weeks
50% 6 weeks

Obviously these are rough estimates and also moving targets: if you check your ROM when you’re already a week or two in, you have to adjust your math. Ideally this is based on tests in the 2-4 days after injury.

Adjust for severity! Counter-intuitively!

Allow longer for the worst strains? Actually, maybe not. The risk of reinjury is weirdly greater with moderate strains. In a 2010 study of 165 elite athletes, moderate strains (grade II) were reinjured at more than double the rate of mild and severe strains (grades I and III): about 24%, compared to 9% and 8%!40 That’s a substantial difference.

Common sense and lots of experience makes it clear that, in general, worse injuries need more time to heal. But the evidence suggests that we should hack that equation just a little and increase our healing time estimate for moderate strains to be closer to what we’d expect for a severe strain.

Adjust for previous injury!

If you’ve injured the same muscle before, the picture is a lot uglier. Previously strained muscle is much more prone to reinjury.41 If you’re in this unlucky situation — and many are — the estimate of the healing time required should go up. But by how much? You should probably double it if you want to play it safe, but add at least 50%. So, for example, imagine a re-strain that causes you to limp for 3 days and, at first, you lose a good third of your range of motion. Both methods above predict that you’ll need 3 weeks, but this isn’t this muscle’s first experience with ripping … so make it 5 weeks, somewhere between 50-100% extra time.

Adjust for age!

You should probably add a week for every decade past the age of 20. Thirty years old? Add a week. Forty? Add two. I’ve got no data to back this up, but I’m sure no one over 30 will question it: it’s as obvious as it is depressing. •sigh•

These methods are pretty useful information when you’re trying to decide whether or not you are healing properly. For instance, suppose it’s been 4 weeks and you’re still suffering from what you thought was a fairly ordinary Grade I strain. If you remember your range of motion being quite restricted, then 4 weeks is not enough: you probably need at least a couple more. But if you never really lost much range of motion … well, then you know that something’s not right, and there may be complications slowing you down.

Method 3: Wait until it isn’t sore to the touch

Another option is to toss all of the above and just go by a single indicator: the sensitivity of the injury site to touch. Athletes are four times more likely to reinjure themselves within a year if they return to normal activity while a hamstring strain is still sore when prodded.42 In other words, you should decide when to get back to normal activity after a strain based on the soreness of the injury spot to touch, not how the muscle feels to contract.

Re-injury risk is not exactly the same as time required to heal, but it’s a pretty strong indicator, and a less abstract one. Who cares if you are technically “healed” if your re-injury risk is still way up there?


The risks of scar tissue

Without proper care, more serious grade II and all grade III muscle strains involve a risk of scarring. Scar tissue can replace damaged muscle cells and permanently limit the function of the muscle.

More serious strains can result in bony scar tissue. This enigmatic condition is called myositis ossificans,43 and involves the calcification of scar tissue into a brittle lump of bone, a sort of bony “tumor.”44 These are painful and significantly reduce muscle function. You really don’t want one! Santa doesn’t bring these to even the naughtiest of boys and girls.

And they are not even especially rare: they are, in fact, among the most common of non-cancerous growths.45 The x-ray shows a particular serious case: a large bony mass in the upper, medial thigh that was a consequence of a “groin pull” (hip adductor) muscle strain.

Despite how not-especically-rare this condition is, it is a really blank area on the scientific map: it is a virtually unstudied condition. Fortunately, it is probably easy to prevent these complications with simple self-care procedures, as presented here.


Vulnerability and risk factors

The usual suspects that (supposedly) increase the risk of a muscle strain are:

  • inadequate warm-up
  • poor flexibility
  • fatigue
  • muscle imbalance (a low hamstring-to-quadriceps ratio)

Warm-up is the only one of those that’s on solid ground; there’s a chapter devoted to it later (Prevention: warmups work).

Low hamstring flexibility is also “considered by some authors to be a risk factor, but it is not consensual, as other studies have shown that flexibility deficit was not associated with injury” (Ramos et al). This has obvious treatment implications, so more on this idea in the chapter about treating with stretch.

I’ll give a little more attention to fatigue and muscle balance in this chapter — because they do not have clear treatment implications.

There’s one more important warning sign that doesn’t get the respect it deserves:

  • painful niggles and twinges during exertion and competition

Such sensations are probably red flags for impending injury. I will return to this advice later in the book: “Heed the signs! Painful ‘niggles’ are a loud-and-clear sign of an increased risk of injury.”

Fatigue: does being worn out make a strain more likely?

Fatigue seems to be accident fuel: something like 6000 fatal car crashes each year may be caused by drowsy drivers (American statistics). And we know that “poor load management” — doing too much too soon, basically — is generally a major risk factor for all kinds of athletic injuries.46

But are stonkered muscles specifically more likely to tear? (Stonkered: New Zealand slang for exhausted. Fun word!)

It is not known.

And are we talking about muscle fatigue here? Or systemic exhaustion from sleep deprivation? These factors might overlap, but they aren’t the same thing.

A 1992 paper suggests — expert opinion, not evidence — that hamstring injuries do occur more frequently in the final stages of competition, when the musculature is at a high level of fatigue.47 But that’s also when the fighting spirit is the most intense, and athletes push harder and take bigger chances, which should result in higher injury rates regardless of fatigue — a good example of how these things are difficult to sort out.

I’d be willing to bet that insomnia and sleep deprivation are indeed risk factors for strains, but it has never been studied specifically. Some studies have identified a link between chronic sleep deprivation and overall injury rates,48 while others have not. For instance, a 2016 study of elite Australian footballers found no connection at all between sleep quality and overall injury rates.49 That’s a surprising result, but it was also a tiny study, so I can keep clinging to my suspicion for now. There’s just not enough evidence on this.

It’s more likely that sleep deprivation is a risk factor for poor recovery, but that’s another topic.

Poor “muscle balance” between the quads and hammies

Allegedly you’re more likely to tear a hamstring if the strength of the hams and quads aren’t balanced, and many a coach has probably wasted their athletes’ time by pursuing a superior “H:Q ratio.” Or maybe it wasn’t a waste: the science is rather confused. However, if the experts are busily logging elite athletes’ H:Q ratios, even though it’s definitely not a reliable and well-validated signal, that says a lot about how little we know about risk factors for strain. For the conflicted details, see the strength training chapter.

More “interesting” risk factors for strain: biology and pathology

There are many other reasons why someone might be vulnerable to a strain, some of them much more interesting than the usual suspects. Consider Andrew’s ominous story of many strains:

I am currently 47 years old and have been playing competitive tennis my entire life. I have struggled with chronic muscle pulls during my entire career and they are only getting worse as I age. Just 4 weeks ago I strained my right calf and today I strained my upper quad hitting a serve — I was not even running!

I have pulled every major muscle in both legs including the hamstrings and groins. Usually I have been well into a match. Today’s quad pull was during the last game of the match (most likely) and after I had been playing for over an hour and a half.

I have no long term health issues and am in very good shape. Joints are all fine and no upper body issues.

That’s not normal, that’s for sure. That’s too many strains! Andrew clearly has a too-many-strains problem. He’s obviously more vulnerable to tearing muscle than the average athlete, and why would that be? There are several plausible pathological explanations, but most would probably have other some signs and symptoms, and none are confirmed. The examples I discuss here are all just educated guesses…

Possible explanations for strain vulnerability

Subtle neuropathy (“trouble with nerves”) is a plausible risk factor for many injuries, and there is a little evidence of this in the case of strain. It’s not a lot to go on, but it’s interesting: one old study found a suspicious amount of “neural tension” in rugby players who kept getting minor hamstring strains.50 Neural what now? More than half of them failed a “slump test,” a position that places tension on the whole spinal cord and sciatic nerve.51 The most obvious explanation for this odd result is that nerve supply to the leg is impaired to some degree, subtly intefering with function and boosting vulnerability to strain. Unfortunately, there has never been another scientific paper on this topic. (Note that this problem did not manifest as a simple lack of hamstring flexibility — the slump-discomfort was the only abnormality noted.) There’s a brief discussion of neural mobilization below in the stretching section.

The hypermobility spectrum disorders and Ehlers–Danlos syndrome seem like prime candidates. These are caused by genetic errors that result in connective tissue that isn’t just more flexible, but more fragile, which leads to all kinds of subtle musculoskeletal hijinks — quite likely including vulnerability to strains. There is such variety within this class of diseases that it’s easy to imagine that some specific versions could increase strain vulnerability while flying entirely below the scientific and diagnostic radar.

Facioscapulohumeral muscular dystrophy is a disease that literally weakens muscle tissue (systemically, even though the most prominent effects are on the arms, shoulders, and head). It’s a surprisingly common and usually relatively mild form of muscular dystrophy. And the milder cases can evade diagnosis indefinitely, all the while causing many minor musculoskeletal symptoms, including stiffness and dystonia… and quite likely excessive muscle strains.52

Fluoroquinolone toxicity is a nasty long-term side effect of a type of antibiotic that is linked to tendon fragility — Achilles tendinitis flare-ups are a classic symptom — but definitely not limited to it. Anything that makes tendons fragile can probably make muscle fragile too53 because tendon blends smoothly into muscle. In 2018, the FDA issued a warning about the toxicity of fluoroquinolones: “… associated with disabling and potentially permanent serious side effects … can involve the tendons, muscles, joints, nerves & CNS.” Yikes. How many people have been affected by this without realizing the source? Yet another surprising cause of pain! I have an unpleasant hunch we’ll be hearing more about fluoroquinolone toxicity over the years. (Update: In early 2019, aortic rupture was added to the list of serious potential harms.)

Pathological muscle contraction. We’ve already talked about how cramps are not the same thing as strains, but a cramping — possibly even just slight cramping — could certainly lead to more strains. There are many kinds of unwanted muscle contractions, from familiar exercise-induced and night cramps and common twitches, to the relatively exotic: dystonia, spasticity, myokemia, clonus, tetany! And many more.54 In fact, there are so many overlapping types of abnormal contraction that it would be quite surprising if some of them weren’t associated with more strains. This large family of strange muscle behaviours makes it clear that muscle doesn’t always do what it’s supposed to, and it’s extremely plausible that some of them are linked to higher rates of strain — even if no one has ever studied it (or is likely to).

It’s even possible that some of those them are much more treatable than others (like if, instead of a bad gene, it’s caused by chronic anxiety, benzo withdrawal, or a mechanical neuropathy).

If you have some pathological vulnerability to strain, diagnosed or mysterious, it will probably also make it harder to recover, because rehab is half about reducing the risk of re-injury — and in some patients, that may be much bigger challenge! More rehab caution and patience is advised for the person with a tendency to suffer too many strains. Even with a strange complication like this, it still makes good sense to understand how to handle strains as well as possible, even if you never understand why you have to be so careful.

And you might never understand. We are way out in the medical weeds here.


Part 4

Treatment, rehab, and prevention

What should you do for a muscle strain? And what shouldn’t you do?

You can do a few things that may improve recovery time and completeness, or at least reduce pain along the way. I will also explain some of the basics of self-treating your trigger points, because they often complicate muscle strain healing.

But it’s important to bear in mind that there are essentially no proven treatments for muscle strain — that is, nothing that definitely speeds healing along, makes it more complete, or eliminates complications. A large 2017 scientific review by Ramos et al concluded that “the evidence of the effectiveness of these modalities in muscle injuries is not fully established due to the little scientific research on the topic.”55 They were referring to cryotherapy, laser therapy, therapeutic ultrasound, therapeutic exercise, and manual therapy, and I will get further into most of these.

The absence of evidence doesn’t mean that nothing works — just that none of the options have really been studied well enough to actually know. Speculation is unavoidable. In many ways, this book is not about “what works,” but about how to make educated guesses about what things are the most worth trying: the safest, the cheapest, the most practical and plausible. Here’s a quick summary of all the options, roughly in order of most promising to least:

  • prevention of re-injury is always the top priority, and the trick is actually understanding the risk factors
  • a progressive rehab plan — disciplined baby steps back to normal function — is important for more serious strains
  • pain free range of motion exercises are very valuable in the early stages of rehab: stimulus without stress
  • warmups: more thorough, and including warmups for workouts that wouldn’t normally need one
  • strength training as rehab progresses, especially “eccentric” training (loading while lengthening)
  • endurance training throughout
  • general self-massage around the strain, and trigger point therapy in some cases
  • icing can be useful for fresh strains in the back
  • contrast therapy (hot and then cold) has some potential to stimulate tissue without stressing it, and may be helpful
  • cramp prevention (which is mostly about avoiding extremes of exertion and overheating, not about staying hydrated or electrolytes)
  • stretching is a mixed bag: it probably has no preventative value, but some treatment value, maybe
  • the drug suramin may aid healing
  • platelet-rich plasma is not promising, but some people may consider it worth the risk
  • pain killers may be useful occasionally, but mostly should be avoided, especially
  • muscle “flossing” (compression) isn’t very promising, but cheap and low risk, an option if you’re scraping the bottom of the worth-a-shot barrel

And there are some treatment approaches that I am so skeptical of that I recommend avoiding:

  • the pursuit of “muscle balance” (hamstring-to-quadriceps strength ratio)
  • cold laser therapy
  • electrical muscle stimulation (EMS)

Prevention: important even after you’ve been hurt

The highest priority in strain rehabilitation is the prevention of reinjury. “Prevention” is treatment, actually: it matters even after you’ve already gotten into trouble. Injury and pain tend to make people a bit accident prone. When one ankle is sprained, it’s easier to trip and sprain the other one. Same with strains! This is called “collateral injury,” and is amazingly common. Injury begets injury.

For more general information about injury prevention, see Sports Injury Prevention Tips.

Reinjury risk seems to be particularly high with strain, as much as 24% in elite athletes.56 One reason could be underestimation of the risk of reinjury because — as noted above in the healing time section — the risk may be weirdly backwards. We naturally assume the risk of reinjury is greater with more severe strains, but Malliaropoulos et al saw just the opposite in their study of 165 elite athletes: moderate strains (grade II) were reinjured at more than double the rate of mild and severe strains (grades I and III).57

Why would less serious strains be more prone to re-injury? I do not know, and maybe the study is wrong. But I can think of two possibilities:

  1. It’s biologically plausible that grade II strains really are more vulnerable. For instance, there could be substantial differences in the amount and type of scarring in severe strains, and the result might be — just speculating here — compromised muscle power but greater durability.
  2. Maybe people are just more likely to push the envelope dangerously with grade II strains. They probably push it even more with grade I strains… but those aren’t nearly as prone to injury.

Whatever the explanation for the data, the reinjury rates are high, and it’s possible that medium-severity tears are counter-intuitively the most likely to tear again.

Also be aware of collateral injuries — new, different injuries that occur because of the first one, such as training another muscle, or blowing a knee because your groin pull is making you sprint a little awkwardly. Some collateral injuries — blown knees, say — are worse than the original injury! When you are hurting, it pays to be more cautious than usual.

Many of the treatment strategies described in the sections ahead also constitute prevention. But there is one particularly important evidence-based prevention tip…


Don’t challenge a strained muscle when the injury site is still sore to the touch

Athletes are an almost unbelievable four times more likely to hurt themselves again within a year if they get back into the action while a hamstring strain is still sore when prodded.58 So clearly you should avoid pushing your luck with a strain based on the muscle’s soreness to touch, not how it feels to contract and use. Sensitivity usually persists for 2-4 weeks after using the muscle starts to feel fine! Here’s some more findings from that study (not already mentioned above)…

A history of re-injury was also a risk factor for yet more re-injury, surprise surprise. If you’ve already been re-injured before, use even more caution.

Weak flexion and limited extension were slightly associated with re-injury risk.

Finally, for whatever it’s worth, the same study found that MRI findings had nothing to do with re-injury rates. It doesn’t matter what the thing looks like on a scan.

So putting all that together, we can build up a picture of a worst-case scenario for re-injury risk:

  • a moderate strain, rather than severe or minor one
  • it wasn’t the first injury to that spot
  • the injury site is still sore
  • you’re a little weak

Put them all together and it’s a re-injury just waiting to happen. And here’s the mirror image, the best-case scenario, the lowest risk of re-injury:

  • your strain was severe or mild
  • it was the first injury ever to that muscle
  • not only is it feeling better to use, but it’s no longer sore to the touch either
  • you seem to have full strength


Prevention: Warmups work

Does a good warmup really prevent injuries? Yes, it probably does. This was strangely unproven by scientific research until quite recently. It made sense, of course — but exercise science is full of surprises, and it’s wise not to assume. For instance, even though warmups are now more or less proven to work, the warmups that work do not include stretching. As explained in the stretching section, pre-exercise stretching does not prevent strains or other injuries whatsoever. So much for common sense!

In both 2008 and 2010, Torbjørn Soligar of Norway published research showing the effectiveness of warmups on a fairly large scale. This research definitely applies to muscle strain, because strains are among the most common of all athletic injuries.

In 2008 he and his team found that athletes who warmed up had fewer traumatic injuries, fewer overuses injuries, and the injuries they did have were less severe.59 In 2010, he reported that injury rates were significantly lower in soccer (football) teams that diligently performed warmup exercises.60

Warmup works

A large study of girls’ soccer teams showed warming up can cut injury rates by about a third. Notably, the warmup does not include stretching!

On the one hand, there was not much difference between a little warming up (low participation) and a bit more warming up (average participation). But players and teams that did an especially good job of warming up (“twice as many injury prevention sessions”) got solid results: “the risk of overall and acute injuries was reduced by more than a third among players with high compliance compared with players with intermediate compliance.” That extra enthusiasm went a long way!

And what was the warmup? Once again (because it cannot be said enough times), stretching was not a part of the warmup program in either of Soligar’s studies. In the 2010 study, he used The 11+, a warmup program developed and endorsed by FIFA, which is fully described on their website. In a nutshell, it simply involves starting slowly and working up to competitive intensity with a series of increasingly difficult challenges to the system — very simple in principle. “Work up to it.”


Strength training, especially eccentric training

Strength training is probably an effective way to rehabilitate a strain and to prevent future strains (re-injury during rehab and new injuries after that). All other things being equal, building up strength in the injured muscle will probably restore normal function faster, and with a lower risk of re-injury too.

The evidence is inadequate as usual, though, and there are some popular misconceptions about the value of strength. For instance, many people are overly optimistic about the power of strength to prevent overuse injuries in runners. Will strength training prevent runners knee? Probably not.61

But muscle strains are another matter, an entirely different kind of injury. And of all injury types, they may benefit the most from strengthing, and at least some evidence supports that.62

A bonus, unproven, but reasonable reason to emphasize strength training is that fatigue is probably a risk factor for strain and re-strain, and stronger muscles are more fatigue-resistant. The effect of fatigue on strain risk is not actually known, as discussed above (Vulnerability and risk factors).

Better yet, there’s a type of strength training that has performed well in some good quality tests, cutting the time elite athletes needed to get back to the game by almost 50%. In this chapter, I’ll explore strength training in general, and then get into detail about that tantalizing special type of strengthening. And there’s also a separate chapter on muscle “flossing,” which is basically just strength training while squeezing muscles with big rubber bands.

Strength training in general

Many people reading this tutorial are athletes or sporty people who are quite comfortable with the idea of strength training … but not everyone is. Building strength is nearly synonymous with gyms, bodybuilding, and “bro” culture — huge turnoffs for many people. But not only is exercise in general the closest thing there is to a miracle cure,63 strength training specifically is arguably the best of all forms of exercise-as-medicine. It’s better and easier — more efficient — than most people realize, and especially for beginners. Beginners can make good progress with amazingly little effort. For instance, contrary to the conventional wisdom, strength training is just as good for general fitness and weight loss as aerobic exercise.64

So “you can’t go wrong” is an understatement. Strength training is well worth doing, no matter what.

And what exactly is “strength training”? Challenging muscles to do their jobs until they are near exhaustion, and then allowing adequate time for recovery and adaptation. Although traditionally strength training tends to involve heavier loads, extensive evidence shows that wearing muscles out by any means is a sufficient stimulus for strength gains. For much more basic information about strength training, see Strength Training for Pain & Injury Rehab.

Some general tips for how to go about using strength training for rehab:

  • For pure prevention, strength training should probably involve relatively intense and fast contractions, which are more similar to athletic challenges. Consider “plyometrics” in particular: exercise where lots of strength is required quickly, like a squat jump (jumping up off the ground from a squat).
  • For rehab, obviously it’s important to be more cautious training muscles that have been ripped. Do not rush it! Take almost absurdly small and slow steps towards bigger loads. For a long time, steer clear of “failure” (training to the point where you can’t lift a load at all). It’s more important to regularly and consistently give the muscle easy challenges than it is to try to build more strength.

Strength training to improve “muscle balance”

A major rationale for strength training is to make the strength and functionality of muscles more “balanced” or symmetrical from side to side, or (especially) from front to back, as allegedly measured by the notorious hamstring-to-quadriceps (H:Q) strength ratio. Unfortunately, it’s not at all clear that such “imbalances” are a cause of muscle strains in the first place. Nevertheless, the concept is so popular that I will devote a whole short chapter to it, coming up right after this one.

An eccentric challenge! Strengthening-while-lengthening is a “proven” rehab method

Now for the more promising, special type of strength training mentioned above.

Muscles are more likely to tear when they are both contracting and lengthening at the same time, which sounds like a paradox but it’s actually a major part of muscle tissue’s job description: “eccentric” contractions put the brakes on elongation, which is why they are also called “braking” contractions.65

They might also be the key to successful rehab. Rehabilitation training should generally try to imitate the circumstances of the injury. That is, you do roughly the same kind of thing that hurt you — more carefully, of course — to prepare your tissues to face the same stresses again someday.

Askling et al tested the effectiveness of eccentric contraction in hamstring strain rehab. Seventy-five elite footballers with hurt hamstrings were randomly assigned to either regular or eccentric rehab exercises. The emphasis on eccentric contraction was wildly successful, taking almost half the time to get players back to the game: 28 days of rehab instead of 51! The error bars on those numbers were wide, but the mean was substantially lower for eccentric contraction. This is a dramatic result, and I actually trust it quite a bit — a rare thing in my job.66

An interesting detail: Askling et al also divided the data by injury type: strains that occurred due to either sprinting or stretching.67 Recovery times were much higher — 84% longer times 59 versus 32 days — for the stretch-type injuries regardless of protocol, but eccentric contractions were still the clear winner.

So what exactly was this miraculous protocol?

The eccentric contraction rehab protocol focused on “loading the hamstrings during extensive lengthening, mainly during eccentric muscle actions.” All exercises were performed painlessly. The exercises were the extender, the diver, and the glider. Here’s the complete routine:68

  1. The Extender — Hold and stabilise the thigh of the injured leg with the hip flexed approximately 90° and then perform slow knee extensions to a point just before pain is felt. Twice per day, three sets of 12 repetitions.

  2. The Diver — A simulated diving motion: hip flexion (from an upright trunk position) of the injured, standing leg and simultaneous stretching of the arms forward and attempting maximal hip extension of the lifted leg while keeping the pelvis horizontal; angles at the knee should be maintained at 10–20° in the standing leg and at 90° in the lifted leg. This is a tricky one, so go slow at first! Once every other day, three sets of six repetitions.

  3. The Glider — The exercise is started from a position with upright trunk, one hand holding on to a support and legs slightly split. All the body weight should be on the heel of the injured (here right) leg with approximately 10–20° flexion in the knee. The motion is started by gliding backward on the other leg (note low friction sock) and stopped before pain is reached. The movement back to the starting position should be performed by the help of both arms, not using the injured leg. Over time, glide further and faster. Once every third day, three sets with four repetitions.

Applying these principles to other muscles would be require some creativity and savvy, but is definitely feasible. If I get sufficient demand by email for any other muscle, I’ll put something together. (Probably the quads?)

Happy contracting-while-lengthening!


Can you prevent strains and re-injury by upgrading your “muscle balance”?

One of the most popular notions in sports medicine is that your muscle strength and function needs to be “balanced” — symmetrical. Like it gets out of alignment, like car tires. Many therapists (especially chiropractors and massage therapists), go to considerable lengths to diagnose and treat these alleged imbalances. This harmonizes nicely with other popular concepts, such as the importance of good posture, core strength, and muscles that are supposedly not “activating” correctly.

This is one of the most common justifications for prescribing strength training to people in rehab for strains, especially athletes.

Unfortunately, there’s no good evidence supporting this practice. We have a lot of decent quality data that has produced some smoke, but no fire has ever been spotted. And there’s certainly some evidence that it doesn’t matter much at all (more below below). And that is also consistent with a huge body of more general evidence showing that alignment/symmetry is mostly a trivial factor in injury risk and other pain problems. Just not that big a deal!69 This muscle balance thing is one of the best single examples of that kind of risk factor.

Front-to-back symmetry: “muscle balance” between the quads and hammies

Supposedly the strength of the quadriceps and hamstrings have to be just-so, or else you are much more likely to rip a ‘string. This is the canonical example of an “inter-limb” asymmetry, an front-back imbalance within one limb (as opposed to comparing right to left). The “hamstring-to-quadriceps (H:Q) strength ratio” is frequently and eagerly measured in the elite sporting world despite the fact that it is not a well-established predictor of injury.70717273 Green et al reviewed studies of basically every kind of strength ratio that has ever been tested:

Isokinetic strength asymmetries or imbalances were not associated with future risk of hamstring injury. Similarly, there was no significant relationship with any strength ratio tested, despite previous reports and isolated study findings. This is consistent with recently published results, including risk examined against specified strength ratio cut-offs, showing a lack of predictive validity for detecting risk of hamstring muscle injury.

But the studies do point in both directions, because they always do. The three papers I just cited are fine papers in lovely journals, including both the British and American Journal of Sports Medicine and all three are (very) wet blankets on muscle balancing. But another good study, Lee in Journal of Science & Medicine in Sport (not quite the same league, but still a good journal), lands on exactly the opposite conclusion:74

Professional football players with significant lower isokinetic hamstring strength, lower hamstring-to-quadriceps strength ratio… were linked to an increased risk of acute hamstring strain injury.

And not just a little bit increased either: more than 5 and 3 times greater risk respectively! It is still “just one study,” at odds with excellent reviews of many other studies (which the authors acknowledge and discuss).75 But it’s an eyebrow-raising result that emphasizes that we probably still have more to learn about this.

For instance, what if we factored in fatigue? This is quite interesting: the H:Q ratio is usually measured in a non-fatigued state, which might not be the best time to check. A 2017 experiment showed that the ratio may get worse when we’re tired — and those ratios-while-fatigued could be better indicators.76

But no one has checked that yet.

My opinion is that tinkering with your H:Q ratio is probably just another supposedly “advanced” method of injury prevention that hasn’t really panned out — a good example of the “correct exercise trap,” a rehab exercise that can’t actually fix a problem that doesn’t exist to begin with.77

Side-to-side symmetry: “muscle balance” between left and right

Lateral symmetry isn’t nearly as big a deal as the H:Q ratio. There’s one particular research example which is particularly relevant to muscle strain. By far the most common muscle strain injuries are in the hips and thighs and occur when playing fast-running, exhausting sports like soccer. If there’s a connection between muscle balance and muscle strains, you’d want to look at the kicking and running muscles of serious soccer players.

Researchers used MRI to measure the size of kicking muscles in 54 Australian Football League players — very serious athletes, these guys — and found that “asymmetry of the psoas and the quadratus lumborum muscles exists in elite AFL players.” This is a prime example of the kind of asymmetries that are so widely believed by therapists to be clinically significant. Manual therapists, if they suspected such a distinct asymmetry in muscle mass, would enthusiastically and almost unanimously embrace this significant lack of “balance” as a major risk factor for injury, and a likely suspect in whatever injury or pain problem a person might happen to be experiencing.

Therefore, they would also almost certainly recommend (expensive, time-consuming) therapy based on this idea: stretching and manipulation for the “over”-developed side, strengthening for the other side, and so on.

However, the researchers also found that “asymmetry in muscle size was not related to number of injuries.”78

Not. Related.

That evidence is pretty strong.

So what to do about muscle balance? Ignore it and strength train for its other benefits

As far as preventing muscle strain goes, you can mosty just stop worrying about whether your strength is “balanced.”

We don’t need the H:Q ratio or any concept of muscle balance to justify strengthening. We already know it’s probably a good idea for other reasons, so just train your muscles, and don’t sweat the specifics much. It’s not practical for most people to either measure their H:Q or train to optimize it, and there’s an excellent chance the ratio doesn’t matter nearly as much as the overall strength and fitness of the muscles. If you’ve torn any thigh muscles, front or back, the injured side is going to be weaker, and you’ll have no way to know what you’re pre-injury ratio was like.

Just focus on cautiously training the injured side until it can match the uninjured side… and then work on making both sides stronger.


Compression band training (AKA muscle “flossing”, AKA blood flow restriction training)

Maybe squeeeeezing strained muscles will enhance rehab or reduce the risk of re-injury? It’s a surprisingly popular idea, often oddly labelled as “flossing.” Because it’s powered by a product — you need a big, special rubber band — there are many branded versions, most notably Rogue Fitness VooDoo Floss and RockFloss. Unsurprisingly, these brands sell their wares with some strong claims:

VooDoo Floss helps break up intramuscular junk to allow for greater mobility and blood supply to an area. By squeezing the muscle in a tight wrap, then forcing it through a full range of motion (ROM), friction between muscle fibers helps break up fuzz, scar tissue, lactic acid and other junk in those tiny places that foam rolling and lacrosse ball techniques can’t address.

Pure therapy babble! There isn’t one valid, plausible concept in there. Maybe flossing works, but not for any of those reasons. Now for the details…

What’s the big idea?

Despite the weird name, basically we’re just talking about just wearing tight bandages around muscles while you exercise them. It’s related to at least three other concepts in training and rehab:

  1. It’s a quirky spin on regular strength training (see last chapter).
  2. It’s kind of similar to Kinesio Tape — also very trendy, that colourful tape that was everywhere at the 2012 Summer Olympic — but wrapped more tightly.
  3. And it’s also a more focussed and extreme version of the older idea of compression garments for performance and rehab — mostly tight leggings and sleeves — which have a long history of vague claims, and evidence of only trivial physiological and sensory effects.79

That’s a highly speculative mechanism and not especially plausible. It’s probably just another flavour of novel sensory input, an unusual sensation that changes our experience enough to convince us that something good is happening.80

I can’t emphasize this strongly enough: the big idea here really is just that it enhances strength-building, which in turn is assumed to be addressing the “weakness” that allegedly underlies most injuries. And that pervasive assumption in the world of physical therapy and rehab has a lot of problems. It’s conceivable that BFRT has some kind of biological effects that are relevant to healing from a muscle strain, but that is not why it’s popular. It’s a trendy thing because of the widespread belief that weakness is lurking behind any injury, and to recover you have to get strong, and BFRT is believed to enhance the strongification of muscles. But even that last part isn’t certain!

So it’s a bit of a conceptual house of cards.

Muscle flossing “science”

It’s the usual mixed bag of inadequate evidence. Some is obviously discouraging.81 Some is encouraging, but only a wee bit. The most notable happy example is a 2017 review in British Journal of Sports Medicine, which actually focusses on BFRT in the context of strength building during rehab (but not rehab for strains specifically). It did not show that BFRT actually improves recovery, just that it enhances strength in people who are recovering82 — for whatever that is worth. And it probably is worth something, as discussed above.

Hughes et al showed that BFRT is slightly more effective than the kind of low-load training you might choose to do when injured, but it’s such a modest difference that it’s completely unclear if it’s worth the bother. For instance, it’s less effective than the high-load training that’s too intense for rehab. And the difference between typical low versus high load training isn’t that great to begin with — it practically disappears when the overall volume is equal — so being a little better than the former but not as good as the latter is splitting hairs.

As usual, the fine print curbs our enthusiasm. There always are some positive studies, but so far we have nothing remotely exciting, a classic example of being damned with faint praise. Results this tepid can be safely regarded as effectively negative.

And then there’s safety. BFR involves a double-whammy of stressors: the exhaustion of the muscle, combined with the constrained blood supply. What could possibly go wrong? Well, oddly enough, you can hurt yourself — probably not very badly if you keep it sane, but it’s certainly possible to overdo it.83

So squeeze away conservatively, and allow for extra recovery time, if you like the idea. Maybe it’s a minor enhancement, and I wouldn’t roll my eyes at anyone keen to try. Well, maybe just a little.


You and “vitamin I”: anti-inflammatory meds, especially Voltaren® Gel

Unmarked pill bottle with white pills spilling out.

Non-steroidal anti-inflammatory drugs (NSAIDs) are based mainly on aspirin, ibuprofen, and naproxen. Vitamin “I”-for-ibuprofen is probably the most obvious and popular method of reducing the pain of a muscle strain, especially in the early stages. Hopefully it’s also obvious that NSAIDs don’t actually cure a muscle strain, or even “speed healing.” With or without NSAIDs, the strain is going to heal at the same speed. However, NSAIDs will make it more comfortable.

This is different than conditions where the inflammation is the problem, such as a tendinitis (sort of84). If the entire problem consists of inflammation, then it may actually be “cured” by an anti-inflammatory drug. But in muscle strain, of course, the problem is the damage — and inflammation is just an uncomfortable part of healing.

Names of common over-the-counter pain killers
Generic name Brand names
Tylenol, Panadol…
Non-steroidal anti-inflammatory drugs (NSAIDs):
aspirin Bayer, Bufferin…
ibuprofen Advil, Motrin…
naproxen Aleve, Naprosyn…
diclofenac (topical) Voltaren, Flector…

NSAIDs can be really good at making a muscle strain hurt less, but they also have clear disadvantages. The main limitation of NSAIDs, regardless of the delivery system, is that there is only so much inflammation they can control: they can only reduce the pain temporarily.

Another problem is that they may give you too much confidence. Pain is a good warning system. If you turn down the volume on that warning system, there’s a real risk that you will push yourself too hard and reinjure yourself. It sounds like such a foolish mistake, but countless people have done this to themselves! Athletes are particularly prone to it: the desire to compete can be much stronger than good sense.

Side effects and more side effects

And yet another problem — that’s three now — there are obviously risks side effects. These drugs are not even remotely harmless. While killing pain somewhat effectively, they may actually retard soft-tissue healing85 (and hard-tissue healing too, for the record86). Oy! So good medicine for strain might be avoiding medicine.

But that’s not all: NSAIDs are also well-known as “gut burners” for their disagreeable and common effects on the gastrointestinal tract, which is a deal-breaker for many patients.

And they increase the risk of strokes and heart attacks, even in healthy people, at any dose. (Diclofenac [Wikipedia], a popular oral NSAID almost everywhere on Earth but North America, has even worse cardiovascular side effects than the others.87 Oral diclofenac specifically should probably be banned.) Lovely!

Still want to take this stuff? Don’t be too alarmed and remember “the dose makes the poison.” Just take them temporarily, and in moderation. The lowest useful dose.

And there’s one really good way to do that…

Topical pain-killer to the rescue (to some extent)

Voltaren Gel — not exactly a magic bullet, but probably safe, reasonable & worth a shot.

Why soak your whole system with NSAIDs and risk all those side effects just to reduce inflammation in the small area of a muscle strain?

Enter Voltaren® Gel! This stuff is really neat. Voltaren® is a useful rub-on anti-inflammatory medication (topical diclofenac). It’s proven effective and FDA-approved for osteoarthritis, and it probably also works for some other kinds of common body pain. The topical form means that dosing is minimal, targeted, and much safer than oral diclofenac.

I think this is one of the best bang-for-buck treatment options for all kinds of aches and pains, including muscle strain. It’s not ideal for muscle strain, mainly because much of a muscle strain is often deeper than the medication can soak in. However, many muscle strains are shallow in the muscle. Although the effect of Voltaren® Gel on muscle strains has not been studied and it is not officially approved (by anyone) for this purpose — it is intended for treating arthritic joints — I think it’s well worth trying, and a great addition to the options.


Please, do not apply heat to a freshly pulled muscle — use ice!

Many people find it tempting to apply heat to a pulled muscle, usually and mainly because they are confusing it with muscle spasm. Whatever you have heard about applying heat in this situation, I promise you that you really should not heat a fresh muscle strain. There are a lot of grey areas in using ice and heat, but this is not one of them. All injury causes inflammation, the basic response of any tissue to trauma. Heat makes inflammation worse — and therefore, the pain and swelling! As mentioned earlier in the tutorial, injured muscle tissue can swell up to about five times its normal volume.

Just say “no” to heating fresh injuries.

But the confusion about this is understandable. The choice between ice and heat for a muscle strain is confusing because people are quite used to getting some benefit from applying heat to muscle. It is somewhat helpful for a number of other muscle problems, such as spasming, post-exercise muscle soreness, or an activated trigger point — three of the conditions that people commonly mistake for a muscle strain — that actually do tend to prefer heat instead of ice. In the case of spasm, heating has a reflex effect that you want: it reduces muscle tone. In the case of DOMS, heat has a soothing, “distracting” anaesthetic effect (although the pain will return shortly after you remove the heat). And in the case of trigger points, again you get a helpful reflexive reduction in muscle tone.

And if you’re supposed to ice injuries but heat other muscle problems, what do you do if they co-exist? What if you have a muscle strain and trigger points, for instance? It’s simple: the most important and immediate thing is clearly to avoid aggravating inflammation with heat. This is the reason for the rule of thumb: “when in doubt, use ice.” Sure, ice might irritate trigger points as well — but that’s not a big deal compared to aggravating an injury!

So, if you really do have a fresh muscle strain, anywhere in the body, you should ice it as much as necessary to control pain. As long as it really is a muscle strain. And a fresh one. Not a spasm or a trigger point. Capisce?

So about ice …

So heat will hurt … but it’s not clear what good ice will do. There’s good reasons to believe it can help, including animal studies,88 but almost no proper (human clinical) evidence at all — it’s an amazingly unstudied treatment.89 But it’s cheap, and completely safe — as long as you don’t give yourself frostbite — and at the very least it almost certainly helps to control pain in the early stages.

Bags of frozen peas and even ice gel packs are not the best choice for icing; instead, use “raw” ice whenever possible. An ice cube held in a dish towel will do in a pinch, or make an “ice cup”: fill a Styrofoam cup with water, freeze it, cut the top inch off, and you have a large ice cube with an insulated handle. (Handy commercial “ice cup” products are now available as well.) Apply ice in slow circles to irritated tissues for two minutes or until you’re numb, whichever comes first. You can do this as often as you like — and many applications may be helpful — as long your tissues warm up between applications.

For minor strains, you only need to ice for the first couple of days. Inflammation may continue to be prominent in a strained muscle for up to 3-5 weeks in the worst strains.

Note that icing only has a realistic chance of helping when the damaged tissue is superficial: ice should remain your first choice for as long as the skin over the injured muscle is obviously warmer than your skin normally is. Once it starts getting hard to tell, it’s time to switch. An injured muscle may actually be inflamed for longer, but it often gets less obvious on the surface. If the inflammation isn’t obvious on the surface, icing is pointless: muscles are much too thick for the cold to penetrate deeply enough to have much of an effect.

So, once the obvious inflammation has died down, it’s time to switch to heating and/or contrast hydrotherapy (see below).


The ice exception in the low back

You need to be careful about icing the low back. If you actually have a real muscle strain in the low back — ripped muscle — then you can ice it. But people routinely mistake low back trigger points for a strain. It is the most common place in the body to have really crappy trigger points that will fool you into thinking you have a muscle strain. Remember, for instance, that you shouldn’t even begin to suspect that you have a muscle strain in the low back unless you had a traumatic lifting incident, where you were, for instance, lifting a piano and had a sudden, horrible oh-shit moment. Then you can ice your low back pain, for the first couple days. Maybe.

But even in cases where injury inflammation is actually present, it is usually deep in the back under a thick layer of insulating muscle and the ice cannot “reach” it. Meanwhile, back pain almost always involves muscular trigger points (muscle knots), which are more likely to be aggravated by ice and helped by heat! For this reason, the majority of people with back pain prefer heat, and a few have negative reactions to ice. For similar reasons, neck pain usually should also not be iced. Although experiments have shown that both ice and heat are modestly helpful for low back and neck pain, there are good reasons to err on the side of heat. Ice should only be used on the back by patients who clearly prefer it (for whatever reason), or when there is definitely a fresh injury.

Please see (Almost) Never Use Ice on Low Back Pain! for more information.


After a few days, use heating or contrasting

Once the worst of the inflammation of injury is gone, switch to gentle heating and “contrasting” (alternating between warm and cool). Heating won’t aggravate a mild or deep inflammatory process, but it will help to reduce muscle tone and therefore help any trigger points in the area. Even better, you can facilitate the remaining healing process by increasing superficial circulation with contrast hydrotherapy …

Contrasting is a powerful, free, easy self-treatment for a wide variety of conditions that can benefit from an increase in circulation (i.e. practically anything except acute injuries). Gentle exercise and movement are excellent ways of increasing circulation as well, but it isn’t always an option to exercise a body part enough to increase circulation — contrasting is useful because it is powerfully stimulating to circulation without any significant risk of irritating tissue. (Please note again: it can’t be used on the freshest injuries, because acute inflammation is aggravated by heat.) Contrasting involves alternating between soaking in hot water and soaking in cold. Always finish with cold. Use a double-sink, a pair of buckets, a detachable shower head ... or whatever arrangement you can dream up.

Please see Contrast Hydrotherapy for more information.


Epsom salt baths: don’t bother

It’s a popular idea, but there is no good reason to believe that bathing in dissolved Epsom salts will have the slightest effect on muscle soreness, injury recovery time, or the risk of cramping (which could injure or re-injure).

But what about the magnesium? Epsom salts baths are basically magnesium baths. As explored in the water and electrolytes chapter, magnesium deficiency is unlikely to be a factor in cramping to begin with… and, even if it was, trying to absorb the stuff through your skin is a poor way to fix it. It’s like going a half hour out of your way to buy stale bread from a corner store when you live next to a good bakery. Just eat more salad! See dietary sources of magnesium.

It is unlikely that the folk wisdom that powers the popularity of Epsom salts bathing will ever prove to be justified. For a lot more detail, see Does Epsom Salt Work?


Don’t bother with Traumeel either

Homeopathic (diluted) herbal ointments featuring Arnica are claimed to be good medicine for muscle pain, joint pain, sports injuries and bruises, but their effectiveness is questionable. Known to most customers as an “herbal” arnica cream, most actually contain only trace amounts — too little to be a chemically active ingredient. Homeopathy involves extreme dilution of ingredients, to the point of literally removing them. Some other herbal ingredients may be less diluted and more useful. However, neither homeopathic or pure herbal creams of this type have produced results better than placebo in good quality modern tests, for any condition.

A muscle strain is exactly the sort of thing that people think Traumeel might help. Worse still, no one actually expects Traumeel to “cure” a muscle strain, and this makes it highly subject to self-delusions. Because a muscle strain is an incredibly painful and acute trauma, no one is surprised when Traumeel has no obvious effect on it. So instead they tend to assume that the Traumeel is “helping” — but of course there is no way to measure this, no way to be sure whether or not Traumeel is making any significant difference. How do you know that it’s improving your healing time? You can’t. There’s no basis for comparison unless you have two identical muscle strains, and you apply Traumeel to one side, and none to the other.

This doesn’t tend to happen with more chronic pain problems, like runner’s knee. In such cases, when the pain has been around and more or less constant for weeks or months, it’s a lot easier to tell whether or not a treatment is making a difference, and therefore a lot hard to fool yourself into believing it’s working when it really isn’t.

So I’ve often heard people say that Traumeel “helped” their muscle strain, but of course they never really know. And the reality is that Traumeel is about as implausible a medicine as you can imagine. Like homeopathic remedies, Traumeel is over-priced and completely ineffective. Homeopathy as a profession is rotten with dangerously irresponsible ideas, as shown in the BBC’s 2006 exposé of homeopaths in London recommending completely ineffective remedies to travellers in place of genuine anti-malarial medication.90 Wikipedia has quite a good complete review of homeopathy.91 For more detailed information about Traumeel, see my article, Does Arnica Gel Work for Pain?.


Self-massage of muscle strains

You can also get some good out of gently rubbing a muscle strain with your fingertips to stimulate the tissue and facilitate healing. This is an option right from the start, with any muscle strain except an actual rupture (and even then it becomes a good idea once you get past the early stages of healing). For the worst strains, you should rub around the site of the tear, and more gently.

There’s no direct evidence that the massage helps with strain recovery, but it’s a reasonable guess that healing is at least a little bit facilitated by stimulation, and there is some indirect evidence of this. For instance, a 2012 animal experiment demonstrated that strained muscle healed quite a bit better when massaged.92

Animal studies don’t come up all that often in my work days, and I find them rather macabre. In this study, rabbits were injured 😮 and then some of them received daily automated massage during recovery, from — I love this bit — an “intelligent massage device.” Their tissues were put under a microscope before and after, and apparently

histomorphology and cytoskeletal structure can be significantly improved after massage, which may help to repair muscle injury by up-regulation of Desmin and alpha-Actin expressions.

In other words, the massage tissue looked a lot healtheir. Sounds good! Hardly smoking gun proof of anything in humans,93 but it’s interesting, promising, and consistent with the fairly sensible notion that moderate stimulation helps tissues recover from damage. If anything, it’s surprising how well it did work!

How intensely should you massage wounded muscle? Let the sensitivity of the tissue be your guide: regardless of whether the strain is mild or severe, simply never massage it so directly or so hard that it hurts more than a little bit. It should always be pretty easy. This isn’t “deep tissue” massage we’re talking about here … just a few minutes a day of easy stimulation.


Getting relief from trigger points

As you move out of the acute stage of the injury, there are often muscular trigger points to be found in that region of the body. As discussed above, they may have been there before, or they may form in response to the injury. Based on what you’ve learned in this article, I can only leave it to you to guess approximately how much of your pain may be coming from trigger points and how much from injury. It could be 60/40 or 30/70.

Trigger points usually will not form directly at the site of the muscle tear (possible, but not typical), but relevant trigger points may very well form in unexpected locations on the far side of nearby joints. Some examples:

  • In the case of hamstring pulls, you could easily develop trigger points roughly in the center of the muscle along its length (halfway down), in the gluteal muscles above the hips, or in the calf muscle.
  • In the case of quadriceps strains, you may develop trigger points anywhere along the length of the group either right on top or more towards the sides, or right at the very top of the front of the hip.

You really just have to explore. Look for sensitive points in the muscle that may produce a pleasing or relieving ache (or not). Press and rub them with your hands or any tool that seems appropriate (tennis ball, for instance). There are many possible refinements to technique, but trigger points have the potential to respond positively to virtually any stimulation.

If trigger points seem to be particularly relevant to your case, then you should definitely learn more about them. For much more detailed information, see:

The Complete Guide to Trigger Points & Myofascial Pain


What about stretching? Can it treat strains, or prevent re-injury?

Stretching is generally over-rated as an exercise ritual94 and particularly irrelevant to muscle strains. In fact, one of the most egregious and debunked myths in the history of exercise and sport is that a pre-workout stretching session will prevent injuries, particularly muscle strains. This is bollocks. A fair amount of research on this topic has been done, and the evidence is quite clear so far: typical pre-workout stretching just has no meaningful effect on injury rates.95 Not convinced? The evidence is thoroughly described in the injury prevention section of my stretching article, Quite a Stretch.

Actually moving and using the muscle is probably much more useful than simply holding it in a lengthened position. In other words, a dynamic warmup. See the warmup section below.

But what about stretching as a treatment?

That’s a different matter.

In spite of my strong general skepticism about the usefulness of stretching for prevention, I wouldn’t hesitate to do some of it as a minor rehabilitation exercise, if I had a strained muscle. It’s not a huge time commitment to stretch one muscle a little, and most of the commonly strained muscles are quite easy to stretch (as opposed to muscles that are quite biomechanically inconvenient to stretch, “the unstretchables”). If you are gentle — staying well within pain tolerance, especially at first — stretching a strain is certainly not going to do any harm, and there are some reasons to believe it might help. Specifically, it may help with scar tissue re-organization: as with gentle contraction of the muscle, stretching may help cue the healing mechanisms in your muscle to lay down new connective tissue in a tidy way.

Better yet, this is supported by a little bit of evidence-based good news in rehabilitation science.96 About 40 Greek athletes who stretched recovered faster than those who didn’t (and the effect is probably not limited to the Hellenic people). How much faster? They regained their range of motion about 22% sooner (5.6 days instead of 7.3), and their “rehabilitation period” was about 12% shorter (13.3 days instead of 15 days). The researchers reported that this was of “great importance in treating muscle strain injuries.” I’m not quite so thrilled by those numbers: getting back in the game about 36 hours sooner is not nothing, but I wouldn’t call it greatly important. One could easily argue that a wee improvement in healing time isn’t worth the risk of injury, or even the tedious routine of stretching.

But it is good news that provides a solid reason to experiment with rehab stretching. I do hope it’s true, even if it’s not of “great importance”!

But you really do need to be gentle! Remember, it’s a muscle tear — something that can be caused by stretching in the first place! Obviously, you can tear a muscle tear more by pulling on it. Fortunately, in the acute phase of healing you can be well-guided by pain: your nervous system is probably not going to happily allow you to pull too hard on traumatized tissue, unless you’re extraordinary determined, foolish and pain tolerant. In any phase of healing, we’re talking only about stretching within pain tolerance, letting pain tell what is safe and what is not. In the later stages of healing, it is probably safe to step a little bit over that line, but only a little, and cautiously. Many professionals have seen too many people stretching in a “gung ho” fashion and placing themselves at serious risk of reinjury, and can hardly be blamed for a better-safe-than-sorry policy. However, it is a biologically sound idea that the right intensity of stretch could well facilitate the healing process — and there is some direct trial evidence of that in the Malliaropoulos paper.

So I encourage you to try it, but please: don’t pull on it too hard, and the warning goes double for more serious strains, earlier in the recovery process, or if the stakes are high for you, or if you think you’re more vulnerable for any other reason. This is rehabilitation, not flexibility training — you’re not trying to make it stretchier, just hanging out at the edge of comfortable elongation.

(I don’t need to point out that you can’t stretch a fresh, complete rupture at all? Because the muscle is in two pieces? Good.)

Another, lesser reason to go ahead and do a little stretching is that it might reduce some of the pain. To the extent that trigger points form in reaction to the injury and are a part of the problem, stretching might help relieve those … but probably not much. Stretching for trigger points is covered (very) thoroughly in the trigger point tutorial, and summarized in my main stretching article: Quite a Stretch.

Stretching nerves? Neural mobilization

Neural mobilization is a technical type of stretching, usually provided by a professional, designed to ease neuropathy by stretching nerves specifically. (Reminder: “neuropathy” usually causes weakness, numbness, tingling, and pain with a zapping/stabbing quality … but just normal pain is possible too, making some neuropathy very hard to diagnose.)

And what does neuropathy have to do with muscle injuries? Well, some strains tear nerves along with muscle.98 So there’s that. Yikes.

And in other cases neuropathy could be a complication, probably due to scarring that prevents nerves from sliding smoothly in their sheaths. This is purely speculative, but plausible.

And it’s even possible that neuropathy could cause some strains, as discussed above in the risk factors chapter. It’s a bit of a reach, but it is an additional reason to consider neural mobilization.

Generally speaking, there’s not much to be done for distressed nerves. Stretching them is one of the only options. Neural mobilization is a bit obscure, and the science is thin, and it’s not clear that it’s sufficiently different from typical self-stretching to justify its cost. But it is a reasonable thing to include in rehab when the stakes are higher — especially if there are some signs of neuropathy in the aftermath of a strain. It may be impossible to know, but tingling and numbness are strong . (Weakness is a symptom of neuropathy too, but it’s also a symptom of strain, so that symptom is of no help here.)

If you’d like to learn more, I have a whole article about neural mobilization.


You need a rehab plan for grade II and III strains

With mild (grade I) muscle strains, this doesn’t really matter much. But for grade IIs and IIIs, it really makes sense to progress rationally with rehabilitation. All of the sections below are relevant to rehabilitation planning only.

Most people who get muscle strains have a tendency to lay off only until the worst of the pain is over … and then want to try their usual athletic activities again. They want to skip the middle step. If this is you, slow down. It is important to spend a little bit of time with some intermediate exercise intensities! Specifically, you need to graduate from very easy pain-free range of motion exercises, and then move into mobilizing exercises, and then into endurance training for the muscle, before you consider anything like strength training or full intensity athletic effort.

Progressive training is a (really) basic concept in athletics and injury rehabilitation. It is most easily understood as the “baby steps” school of training and rehab, in which challenges are broken up into small intermediate goals. All serious athletes train progressively, because it’s the only way to get the job done. It is the basis of every running group. Runners who patiently increase the length and intensity of their runs are training progressively, and are at much lower risk of injury. The principle is the same whether you are fit and working towards an athletic goal, or injured and simply trying to get back to normal. It’s as powerful an idea as it is simple, and a great example of advice that is both “boring” and yet desperately needed by most clients — this probably means you!

For more information, see Progressive Training.


Part 4.17


Reader feedback … good and bad

Testimonials on health care websites reek of quackery, so publishing them has always made me a bit queasy. But my testimonials are mostly about the quality of the information I’m selling, and I hope that makes all the difference. So here’s some highlights from the kind words I’ve received over the years … plus some of the common criticisms I receive, at the end. These are all genuine testimonials, mostly received by email. In many cases I withold or change names and identifying details.

Just to let you know your style and thoughts are so much more on target than anything I have ever read. I’m an engineer, runner, father of eight, kids that are doctors, and I find that so little is properly discussed or backed up with evidence and decent reasoning. I may not agree with everything, but I’ve come to trust that you are diligent and earnest and know your subject matter as well as anyone.

Greg Lennon

The internet is a dicey place to spend money ... so many scams. I wanted to let you know how appreciative I am of your eBook on muscle strains. When I got to the stop sign, I had to reflect and realized that the style and quality of what you had written was worth a gamble. Well, paying the twenty bucks and learning what I wanted to learn — and more — was worth every penny. I am now rehabbing my level 1 calf strain with full confidence and feel very well informed moving ahead. Good luck and keep writing — we need all the help we can get out here!

Craig Adkins, tennis player and professional skiing cameraman, Portland, Oregon

I read your article on muscle strains, and I was very impressed. You seem to really know your stuff. I wish there was one of you in every state!


I found this article when I was researching how to heal my pulled muscle. I love the mobilization exercises at the end — great for a ‘desk jockey’ like me!

Juanita Vannay

One more noteworthy endorsement, with regards to this whole website and all of my books, submitted by a London physician specializing in chronic pain, medical education, and patient-advocacy (that’s a link to his excellent blog):

I’m writing to congratulate and thank you for your impressive ongoing review of musculoskeletal research. I teach a course, Medicine in Society, at St. Leonards Hospital in Hoxton. I originally stumbled across your website whilst looking for information about pain for my medical students, and have recommended your tutorials to them. Your work deserves special mention for its transparency, evidence base, clear presentation, educational content, regular documented updates, and lack of any commercial promotional material.

Dr. Jonathon Tomlinson, MBBS, DRCOG, MRCGP, MA, The Lawson Practice, London

What about criticism and complaints?

Oh, I get those too! I do not host public comments on for many reasons, but emailed constructive criticism, factual corrections, requests, and suggestions are all very welcome. I have made many important changes to this tutorial inspired directly by critical, informed reader feedback.

But you can’t make everyone happy! Some people demand their money back (and get it). I have about a 1% refund rate (far better than average in retail/e-commerce). The complaints of my most dissatisfied customers have strong themes:



Thanks to every reader, client, and book customer for your curiosity, your faith, and your feedback and suggestions, and your stories most of all — without you, all of this would be impossible and pointless.

Writers go on and on about how grateful they are for the support they had while writing one measly book, but this website is actually a much bigger project than a book. was originally created in my so-called “spare time” with a lot of assistance from family and friends (see the origin story). Thanks to my wife for countless indulgences large and small; to my parents for (possibly blind) faith in me, and much copyediting; and to friends and technical mentors Mike, Dirk, Aaron, and Erin for endless useful chats, repeatedly saving my ass, plus actually building many of the nifty features of this website.

Special thanks to some professionals and experts who have been particularly inspiring and/or directly supportive: Dr. Rob Tarzwell, Dr. Steven Novella, Dr. David Gorski, Sam Homola, DC, Dr. Mark Crislip, Scott Gavura, Dr. Harriet Hall, Dr. Stephen Barrett, Dr. Greg Lehman, Dr. Jason Silvernail, Todd Hargrove, Nick Ng, Alice Sanvito, Dr. Chris Moyer, Lars Avemarie, PT, Dr. Brian James, Bodhi Haraldsson, Diane Jacobs, Adam Meakins, Sol Orwell, Laura Allen, James Fell, Dr. Ravensara Travillian, Dr. Neil O’Connell, Dr. Tony Ingram, Dr. Jim Eubanks, Kira Stoops, Dr. Bronnie Thompson, Dr. James Coyne, Alex Hutchinson, Dr. David Colquhoun, Bas Asselbergs … and almost certainly a dozen more I am embarrassed to have neglected.

I work “alone,” but not really, thanks to all these people.

I have some relationship with everyone named above, but there are also many experts who have influenced me that I am not privileged to know personally. Some of the most notable are: Drs. Lorimer Moseley, David Butler, Gordon Waddell, Robert Sapolsky, Brad Schoenfeld, Edzard Ernst, Jan Dommerholt, Simon Singh, Ben Goldacre, Atul Gawande, and Nikolai Boguduk.


Further Reading

Here are several additional articles of interest:

And here are the articles recommended for those of you who may have muscle knots, as opposed to a muscle strain:


What’s new in this tutorial?

Regular updates are a key feature of tutorials. As new science and information becomes available, I upgrade them, and the most recent version is always automatically available to customers. Unlike regular books, and even e-books (which can be obsolete by the time they are published, and can go years between editions) this document is updated at least once every three months and often much more. I also log updates, making it easy for readers to see what’s changed. This tutorial has gotten 60 major and minor updates since I started logging carefully in late 2009 (plus countless minor tweaks and touch-ups).

2022 — More information: Added an additional reason for imaging: some “strains” turn out to be stress fractures. [Updated section: Diagnostic imaging.]

2022 — Science update: Cited Guan, a good review of all inter-limb asymmetry evidence. [Updated section: Can you prevent strains and re-injury by upgrading your “muscle balance”?]

2022 — Minor update: Added neuropathy as a risk factor for strain. [Updated section: Vulnerability and risk factors.]

2022 — Added sub-topic: Discussed the potential value of neural mobilization in strain rehab. [Updated section: What about stretching? Can it treat strains, or prevent re-injury?]

2021 — Upgraded: Added much more information about magnesium: cramping, supplementation, and dietary sources. Also beefed up the warning about excessive hydration and its effect on electrolytes (hyponatremia). [Updated section: Prevention: will water and electrolytes make a difference? Magnesium?]

2021 — More information: Added information about the role of magnesium. [Updated section: Epsom salt baths: don’t bother.]

2021 — Upgraded: More and clearer information. A new citation to some basic spasm science. [Updated section: Could you have a muscle spasm instead of a strain?]

2021 — Correction: I misinterpreted a study of the relationship between range of motion and recovery time. While the general principle was sound — greater ROM loss correlates strongly with recovery time) — my more specific “rule of thumb” based on it was a bit wonky. So I fixed that. [Updated section: Timing tips: when is it safe to use a torn muscle again?]

2021 — More info: More detailed information and advice about training for “muscle balance” between the quads and hamstrings. [Updated section: Can you prevent strains and re-injury by upgrading your “muscle balance”?]

2020 — New chapter: No notes. Just a new chapter. [Updated section: Heed the signs! Painful “niggles” are a loud-and-clear sign of an increased risk of injury.]

2020 — Major upgrade: Added a bunch of new information about conventional risk factors. [Updated section: Vulnerability and risk factors.]

2020 — Improvements: Science updates, updated side effect information, and just generally more detail. [Updated section: You and “vitamin I”: anti-inflammatory meds, especially Voltaren® Gel.]

2020 — Major revision: Information about spasms and cramps is now more detailed and nuanced. Some significant modernization was needed. [Updated section: Could you have a muscle spasm instead of a strain?]

2020 — Upgrade: Clarification what different combinations of strength and pain might mean. [Updated section: The hurtin’ and the weak.]

2020 — Upgraded: Major improvements and clarifications, inspired by some good scholarly debate about the classification of muscle injuries. A formal classification of some muscle injuries as “functional” is an interesting and useful way to introduce the subtopic of trigger points, and to put it in the context of a book about structural muscle injury. [Updated section: Could you have muscle “knots” instead of a muscle strain?]

2020 — Science update: Added a good new citation about the definition/classification of strain, clarified the unclear nature of “strain,” and introduced the idea of other kinds of muscle injury. [Updated section: So what is a muscle strain exactly?]

2020 — Science update: Added a citation about the safety of BFR training (it’s not entirely safe, turns out). [Updated section: Compression band training (AKA muscle “flossing”, AKA blood flow restriction training).]

2020 — Science update: Added some information about the potential harms of platelet-rich plasma injection. [Updated section: Regenerative medicine? Platelet-rich plasma.]

Archived updates — All updates, including 36 older updates, are listed on another page.

2009 — Publication.



  1. Bret “The Glute Guy” Contreras tells his story, and some other tales of extreme recovery, and extracts some lessons from them. See You’ll Never Squat Again.
  2. Simons D. Foreword of The Trigger Point Therapy Workbook. 1st ed. New Harbinger Publications; 2001. “Muscle is an orphan organ. No medical speciality claims it. As a consequence, no medical specialty is concerned with promoting funded research into the muscular causes of pain.”
  3. You can get a rough measure of how well-studied a subject is by doing a search for it on PubMed, a large database of citations to medical research. Searching for muscle strain is a bit tricky, because “muscle strain” is mentioned in lots of papers that aren’t really about muscle strain. But if you cleverly search for the terms “muscle strain” only in titles, you will get, as of 4/14/07, only 61 search results, even less than iliotibial band syndrome (another under-studied condition). Compare that to, say, 3000 for frozen shoulder, or 5900 for carpal tunnel syndrome.
  4. Ramos GA, Arliani GG, Astur DC, et al. Rehabilitation of hamstring muscle injuries: a literature review. Rev Bras Ortop. 2017;52(1):11–16. PubMed 28194375 ❐ PainSci Bibliography 52750 ❐
  5. Doctors lack the skills and knowledge needed to care for most common aches, pains, and injury problems, especially the chronic cases, and even the best are poor substitutes for physical therapists. This has been proven in a number of studies, like Stockard et al, who found that 82% of medical graduates “failed to demonstrate basic competency in musculoskeletal medicine.” It’s just not their thing, and people with joint or meaty body pain should take their family doctor’s advice with a grain of salt. See The Medical Blind Spot for Aches, Pains & Injuries: Most physicians are unqualified to care for many common pain and injury problems, especially the more stubborn and tricky ones.
    Cartoon of a man sitting in a doctor’s office. The doctor is holding a clipboard with a checklist with just two items on it: stress related and age related. The caption reads: “An extremely general practitioner.”
  6. Mueller-Wohlfahrt HW, Haensel L, Mithoefer K, et al. Terminology and classification of muscle injuries in sport: the Munich consensus statement. Br J Sports Med. 2013 Apr;47(6):342–50. PubMed 23080315 ❐ PainSci Bibliography 52361 ❐

    In a 2013 survey of professionals, “responses demonstrated a marked variability in the definitions for hypertonus, muscle hardening, muscle strain, muscle tear, bundle/fascicle tear and laceration, with the most obvious inconsistencies for the term muscle strain. Relatively consistent responses were obtained for pulled muscle (Layman’s term) and laceration.”

  7. Strain and sprain are confusingly similar words for quite different things. They both refer to tearing, but of different tissues. A torn ligament is always called a sprain. A torn muscle is always called a strain.

    c.1400, from Old French spasme, from Latin spasmusspasmus “a spasm,” from Greek spasmos “a spasm, convulsion,” from span “draw up, tear away, contract violently, pull.” Figurative sense of “a sudden convulsion” (of emotion, politics, etc.) is attested from 1817.

  9. Mueller-Wohlfahrt 2013, op. cit.

    Mueller-Wohlfahrt et al classify muscle injuries into two broad categories, functional and structural. The structural injuries are the obvious traumatic injuries that this volume is mainly about: partial and total tears and avulsions, injuries you can easily see with a microscope if not with the naked eye.

    The functional injuries are divided into “overexertion-related” and “neuromuscular muscle disorders,” which are defined by their lack of clear physical damage. This category is messy but interesting. The overexertion category includes a bunch of muscle issues of unclear nature. The neuromuscular disorders refers mainly to muscle that is being irritated by spinal cord lesions.

  10. Rozen, I and Dudkiewicz, I. “Wound Ballistics and Tissue Damage.” Chapter in: A. Lerner and M. Soudry (eds.), Armed Conflict Injuries to the Extremities, 21 DOI: 10.1007/978-3-642-16155-1_2, Springer-Verlag Berlin Heidelberg 2011.
  11. Mild strains can come on relatively slowly. I have experienced at least two “slow” muscle tears of my left quadriceps while playing ultimate (a hard-running Frisbee sport). I recall in each case that there was definitely a moment of injury — but it was kind of a long, drawn-out moment. I stumbled a little. There was some pain, but not enough to stop me at first. As I kept running, though, it became clear that I was going to be benched. I had torn a few fibres, perhaps, and I was tearing more as I ran — a slow rip, a few more fibres with every step. The sense of impending doom was very strong! So, in this case, the onset was not exactly a “sudden” attack of serious pain, but it was still a perfectly clear, well-defined, can’t-miss-it kind of event.
  12. O’Laughlin SJ, Flynn TW, Westrick RB, Ross MD. Diagnosis and expedited surgical intervention of a complete hamstring avulsion in a military combatives athlete: a case report. Int J Sports Phys Ther. 2014 May;9(3):371–6. PubMed 24944856 ❐ PainSci Bibliography 53845 ❐
  13. Example: if you rupture your Achilles tendon, you lose nearly all of your ankle plantarflexion strength. The only muscles pulling on the back of the heel are the gastrocnemius and soleus, which make up almost all the bulk of the calf, and all that strength is funnelled into the Achilles tendon.
  14. Imagine you’re a tough athlete, like the guy in the cited case study, a mixed martial arts fighter! How do you feel if you lose about one third of the strength in your hamstrings? You know something’s wrong, for sure … but you’re tough, so you probably don’t make all that much of it. “Doc, I hurt something and I don’t think I’d want to fight right now, but I can still walk around fine.” You don’t need anywhere close to full strength most of the time … so being 30-40% short is really not that big a deal.
  15. Was it really the electrolytes? No. That’s what I thought at the time, but a nice myth-busting 2011 experiment comparing crampy runners with their uncramped comrades showed clearly that dehydration was not the culprit. Fun science. See Schwellnus et al. This will be discussed a bunch more in the water and electrolytes chapter of this book.
  16. Weakness has many possible causes — too many to just start listing them as candidiates without more information about the case to narrow it down. But in a patient who otherwises suspects a muscle injury, isolated weakness of a movement is most likely to be caused by a neuropathy — an impinged nerve somewhere. That’s where the clinical suspicion would be most likely to point.

There are 100 more footnotes in the full version of the book. I really like footnotes, and I try to have fun with them.

Jump back to:

The introduction
Paywall & purchase info
Table of contents
Top of the footnotes

Logos for Visa, Mastercard, and Amex.

Paying in your own (non-USD) currency is always cheaper! My prices are set slightly lower than current exchange rates, but most cards charge extra for conversion.

Example: as a Canadian, if I pay $19.95 USD, my credit card converts it at a high rate and charges me $26.58 CAD. But if I select Canadian dollars here, I pay only $24.95 CAD.

Why so different? If you pay in United States dollars (USD), your credit card will convert the USD price to your card’s native currency, but the card companies often charge too much for conversion — it’s a way for them to make a little extra money, of course. So I offer my customers prices converted at slightly better than the current rate.

read on any device, no passwords
refund at any time, in a week or a year
call 778-968-0930 for purchase help


linking guide

4,250 words (free intro)
36,000 (whole book)