• Good advice for aches, pains & injuries

What Can a Runner With Knee Pain Do at the Gym?

Some training options and considerations for runners (and others) with overuse injuries of the knee

Paul Ingrahamupdated

This article covers some exercise/training options and considerations for runners and other athletes with overuse injuries of the knee, mainly patellofemoral syndrome and iliotibial band syndrome, the two kinds of runner’s knee. I will give some specific examples of “active resting” strategies for these injuries, and exercises that are good for the legs but less bad for your knees. The goal is to maintain some fitness, especially leg strength, without sabotaging recovery.

In my books and articles on ITBS, PFPS, and other RSIs, I have strongly emphasized the under-rated importance of resting in rehabilitation — a somewhat contrarian position.1 The art of rest is more important and difficult than it seems. Taking enough stress off overloaded tissues is a critical missing piece from many stubborn cases of repetitive strain injury. Doing it in a way that protects and preserves fitness at the same time is a particularly tricky challenge, especially with knees.

I have written books about both PFPS and ITBS and have corresponded extensively — thousands of emails — with patients around the world. One of the most common themes in those discussions is that runners, once they are convinced that they need to rest more than they thought, want to know:

So what can I do instead of running?

It “should” be relatively obvious: do any exercise at all that doesn’t piss off your knees! You just work around the pain instead of working through it. But there is clearly an emotional element to the challenge that makes sensible and creative planning difficult. Runners want to run, and non-running options do not compute. As I have pointed out so often, in so many ways, injured runners’ are often their own worst enemies.2 (Same goes for any athlete, of course: runners are just a useful example.)

Most runners wonder about strength training of the leg in particular, because they want to keep their legs in shape, and/or because they heard that it will directly help knee pain. It's a healthy impulse, of course: strength training is quite a beneficial form of exercise in general, and more efficient than most people realize.3 The problem is that people often end up choosing exercises that cause the knee excessive stress! Or, they exercise too much. Rehabilitation is a careful balancing act between exercising enough to stimulate recovery, but not so much as to aggravate symptoms.4

Strength training safely around patellofemoral pain syndrome

The leg press machine is one of the most popular in the gym. It is completely off-limits for patients with patellofemoral pain.

What is the risk of harm that needs to be avoided? Any strong knee straightening — heavily loaded knee extension starting from a bent position — impressively increases pressure between the kneecap and the femur, and therefore is potentially a major risk factor. Therefore, the PFPS patient must, in my opinion, initially avoid the two most classic thigh strength training exercises, and continue avoiding or minimizing them until recovery is well under way:

  1. the leg press machine
  2. any kind of squat, deep knee bend

That’s unfortunate, because those exercises are favourites for a reason: they use huge muscle groups, the so-called “anti-gravity” muscles, the quadriceps, hamstrings and gluteals, and using them intensely is a great workout, and an important long term goal that you will slowly build towards. However, in the short term, working them hard is off limits.

Fortunately, virtually anything else is perfectly fair game … even other exercises that use the knees. In some cases, using the knee at all causes more pain, in which case working the hips first should be a safe and effective alternative (and you should be working them anyway). See below for examples.

Hamstring curls. For instance, a good replacement is to work the large hamstring muscle group with a hamstring curl machine. This is a much less popular piece of gym equipment for some reason, but it’s certainly useful here. When you squat or leg press, the powerful hamstrings are involved and the patellofemoral joint is squeezed mightily. But a hamstring curl contracts the hamstrings without significant strain on the patellofemoral joint — it’s like magic.

What’s the difference? Knee action can be powered from either side of the joint. The quadriceps pull one way from one side, and the hamstrings pull the other way from the other side. The quadriceps pull on the front of the tibia (the big lower leg bone), while the hamstrings pull on the back. The quadriceps are more powerful, and have better leverage — the actual biomechanical purpose of the kneecap. But the hamstrings are also extremely strong … and they can’t move the knee without cinching up that patellofemoral joint either.

Illustration of a woman using a hamstring curl machine.

In a squat or leg press, it’s all going on: both groups are working in concert to powerfully extend and to control flexion. But the hamstring curl eliminates the quadriceps from the equation, forcing all knee movement to be powered by the hamstrings alone — a less powerful movement, but still a big muscle group hard at work.

Certainly the knee is still bending and therefore the patellofemoral joint is compressing, as it always does with any flexion past a few degrees, loaded or unloaded, and so patients with severe PFPS may want to avoid this too: but it is a much less stressful exercise for the patellofemoral joint than the squat or leg press. This makes it a fine compromise exercise for many people. The hamstrings have a lot of mass, and you can build a lot of fitness by strengthening them, just as you can by training the quadriceps.

There is still some strain on the patellofemoral joint in a hamstring curl, so we can refine the exercise a little more to make it a bit safer: just limit the degrees of flexion. Don’t bend the knee as far. Every degree of flexion increases the pressure in that joint, but you don’t have to use all of the degrees available. Curl half way! Curl 60˚ instead of 120˚!

Quadriceps setting. Another option (which doesn’t actually require the gym) is “quadriceps setting” — basically just clenching the thighs, with the knee straight or nearly so to avoid compression of the patellofemoral joint. Starting with a straight knee, simply “set” (clench and hold) your thigh muscles. Start gently and slowly get stronger, both in each session and over time. An appropriate regimen might be 3 sets of 10 clenches daily, increasing to 3 sets of 30 over a period of time. I also recommend that people try doing the exercise on both sides simultaneously (even if the symptoms are one-sided).

Straight leg raises. Generally speaking, a cautious quadriceps program would progress from setting exercises — no movement — to the very simple and knee-safe movement of straight leg raising. Lifting the straight leg challenges one segment of the quadriceps — the rectus femoris muscle, which also crosses the hip — and can be performed with a nice straight knee. Lying on the ground, first turn the foot slightly outward, then “set” (clench) the quadriceps, and then lift the whole leg to about 45 degrees. This is pretty good exercise for one portion of the quadriceps, as well as other hip flexors.

Side lying straight leg raises. The sideways sister of the straight leg raise, this exercise targets hip muscles without placing much stress on the knee itself. Lay on your side with your legs straight so your shoulders, hips, knees, and feet make a straight line, and one leg is resting on top of the other. From there, lift the leg straight up to about 45° from the floor and hold for 2 seconds. Return and repeat until the hips fatigue, or pain gets in the way (don’t push through the pain). Work up to three sets of 10-15 reps.

“Clam Shells”. The little sister of the above “side lying straight leg raise”. Often scoffed at as a wimpy exercise, this exercise can be extremely useful at the beginning of a rehabilitation program when the pain is simply too intense to do anything else. It should be considered a first baby step in the progression to more complex exercises, such as its big sister, or weight bearing exercises like lunges and squats. Lying on your side, bend both knees so both of them point forward, while the shoulders, hips, and feet make a straight line. Simply open the knees (like opening a clam shell) while keeping the waist from twisting (that’s cheating). Hold the top for 2 seconds, and return to start. Repeat until you feel the hip fatigue, working your way up to three sets of 15-20 reps.

I recommend performing all exercises on both sides. It takes more time but research has shown that one sided pain can lead to weakness in both sides.5 I know, pain is weird. Do both sides.

There’s more, of course, but these suggestions should certainly get you started and illustrate the principle. Heather Stanton is a PFPS sufferer and reader who has devoted quite a lot of time to understanding the condition and helping others. In this video, she demonstrates some of these ideas, and others. Thanks, Heather!

Heather's knee friendly lower body exercise 9:02

Strength training around iliotibial band syndrome

ITBS is all about repetitive movement, so any repeated knee flexion at all is a risk, regardless of what kind of knee flexion. Every single swing of the knee is potentially a problem. It’s a numbers game.

Not all flexion is created equal, and the risk varies with different exercises. For instance, it’s clear that cycling is generally less irritating to ITBS than running, even though it is just as repetitive. But it is by no means risk free, and some ITBS patients have just as much difficulty with cycling as they do with running. At the other extreme, the biomechanics of climbing down a mountain are especially bad for ITBS (for no super-clear reason — but that’s the way it is).

To truly rest an ITBS knee, then, you simply have to limit the number of swings of that hinge.

Strength training at the gym may be quite a good choice, though, because it is possible to strength train with minimal repetitions. In fact, strength training is offers the best trade-off between maximum benefit for a minimum number of repetitions. By definition, strength training involves just a few intense contractions: “high load” but “low reps” (repetitions). The goal is to quickly exhaust muscle fibres, in just 10-20 repetitions, or a couple of minutes. The knee joint is under a lot of strain … but not from repetition.

A dozen knee bends is an extremely small number compared to what it will be subjected to in even the shortest run!

Better still, repetitions can be minimized even further with the slow contractions favoured by some experts. Five slower repetitions spread out over a couple minutes may be even better than 15 repetitions, or the equal of it. This is debated ad infinitum by the bodybuilding experts, but it doesn’t really matter for our purposes: slow contractions may or may not be the absolute best training style, but who cares as long as it works reasonably well and limits repetitions? It’s just gravy if it also happens to work a little better.

The heavy loading might still be a problem for some people. But test it: what happens when you do a set of leg presses or squats? How irritating is it compared to a run?

Two examples of rehab compromises

The creative challenge of resting always involves trade-offs and compromises. Short of living in a wheelchair, it is literally impossible to avoid all knee irritation. Strength training the legs is a way of continuing to exercise your legs while minimizing — not eliminating — the risks to an injured knee.

This may be an extremely useful strategy for many patients … and not at all for others. Here are two contrasting examples, Young Running Man and Old Walking Lady:

Younger Running Man. YRM is a serious amateur athlete with IT band syndrome, preparing for a career move: officer’s training school (OTS), which has some serious minimum fitness requirements. They are easy enough to meet for a reasonably athletic person, but tricky with an injury. He starts in about four months. The stakes are high, he’s never really encountered any serious setbacks as an athlete before, and he’s understandably reluctant to rest!

This guy is a perfect candidate for strength training his legs: he has a real reason to continue preparing his body for the ordeal ahead, and yet he also badly needs to protect his knees. There’s almost no chance that his knee will actually be fully recovered by the time he gets to OTS, but he can at least get it as calm as possible. He doesn’t have to be pain-free to get through OTS, just pain-free enough! A high-intensity style of strength training for the legs is a good compromise here: good training with a minimal knee movement. He can start OTS with legs in excellent overall condition, and knees as un-irritated as possible.

Older Walking Lady. OWL is a PFPS patient with radically different set of priorities: her main concern is being able to maintain general fitness with a walking habit, which is a great goal … but there’s no career at stake, no deadline, and no challenging physical! Even though she could strength train her legs, there’s really no need for her to risk irritating her knees at all: it probably makes sense to avoid all knee stress entirely for a while. Her general fitness can easily be rebuilt when her knees are ready to get back to walking. But she can and should — if she is at all earnest about her health — also maintain her general fitness by strength training other musculature in the body.

Like many older women — perhaps most — she’s not particularly keen on the gym. However, for the sake of her worthy goal, she can cope. Muscle mass drops off sharply later in life, and maintaining it is more than just a good idea: it is almost a necessity. Switching to a fitness programme dominated by strength training for a few months is a small price to pay for maintaining fitness while also allowing complete rehabilitation of the knees. Soon enough, walking will become an option for her again … although by that time she may have discovered that the gym isn’t so bad. 😃

Maybe she’ll even start to enjoy being surrounded by young male bodybuilders at the gym!

I do go on about rest, don’t I? I do it because resting effectively for rehab is just not as easy or simple as it sounds. All of the above is a demonstration of what I mean by being “creative and precise” with a resting “strategy”: with some savvy planning, you can almost always find ways to get an excellent workout and yet still protect tissues that truly need a break. If I had a buck for every time I’ve seen this “simple” thing done well in cases where the need for it was clear — often desperate — I would have enough about enough money for a cheap lunch.

About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter.

Related Reading

This article is a free chapter from’s huge patellofemoral pain syndrome (PFPS) tutorial, one of 100 chapters in all. There are also several other excerpts and articles on the site about patellofemoral pain and related topics:

What’s new in this article?

2018 — Revised the introduction, added four new exercise examples for PFPS patients, and added some footnotes. More to come on ITBS.

2011 — Publication.


  1. My advice is at odds with the conventional wisdom in that patients with patellofemoral pain (especially) are often told to treat the condition with exercise alone, by strengthening the quads; I think it’s important to rest first, consistent with the basic rehab principle: “calm shit down, then build shit up” (Tweet, Sep 24, 2014, Greg Lehman, physical therapist and chiropractor. This debate is covered thoroughly in my advanced PFPS tutorial. In a nutshell, I have yet to see persuasive evidence that quads strengthening alone is an effective treatment for PFPS, especially alleged isolation of the vastus medialis. Meanwhile, there is an obvious reason why such training might actually do harm. Until it is proven safe and effective, I will continue to exercise the precautionary principle and warn people away from jumping right into quadriceps training as the first step in PFPS treatment.
  2. — SweatScience [Internet]. Hutchinson A. Why Perfectionists Get More Shin Splints; 2018 October 19 [cited 18 Oct 27].
  3. Research shows strength training is a much more efficient form of exercise than most people realize, and almost any amount of it is much better than nothing. You can gain strength and all its health benefits fairly easily. For more information, see Strength Training Frequency: Less is more than enough: go to the gym less frequently but still gain strength fast enough for anyone but a bodybuilder.
  4. Nowhere has this balancing act been better demonstrated than in research on tendinopathy. Arampatzis et al demonstrated that tenocytes (tendon cells) adapt to the forces they usually encounter, creating a “set point” depending on what they are "used to."

    Interestingly, disuse will lower the set point, and exercise will increase it. However, if the exercise is too frequent or intense, the cells can become damaged. The moral of the story: don’t skip steps in training — build yourself up gradually!

  5. Hart JM, Pietrosimone B, Hertel J, Ingersoll CD. Quadriceps activation following knee injuries: a systematic review. J Athl Train. 2010;45(1):87–97. PubMed #20064053 ❐ PainSci #53957 ❐

    This study reviewed the existing research on "arthrogenic muscle inhibition" — defined as an inability to fully activate your muscle voluntarily due to joint problems as opposed to muscle or nerve problems. Specifically, it investigated AMI as a factor in persistent quadriceps weakness after knee injury or surgery.

    The results of this study indicate that many different knee issues indeed cause a 10 to 20% decrease in voluntary quadriceps activation. This includes people who have had ACL ruptures (which remains even after surgical repair), osteoarthritis, and anterior knee pain syndromes.

    Interestingly, it also seems that this quadriceps inhibition exists in both legs — even for one sided injury or pain!