Sensible advice for aches, pains & injuries

Toxic Muscle Knots

Research suggests myofascial trigger points may be quagmires of irritating molecules

updated (first published 2008)
by Paul Ingraham, Vancouver, Canadabio
I am a science writer, the Assistant Editor of, and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about

What is the chemistry of a muscle knot? (For that matter, what’s a muscle knot?) Specifically, what’s the toxicity of the tissue fluids in and around them?

The science of myofascial trigger points (TPs) has been dominated for years by the theory of a poisonous feedback loop, a vicious cycle. The idea is that knots generate a lot of tissue fluid pollution, waste products of muscle cells that are metabolically “revving” with intense contraction … and those “exhaust” molecules are then accumulating, causing pain and other symptoms, and irritating the TP even more.

This is called a metabolic energy crisis, and it’s why I’ve been informally calling trigger points “sick muscle” syndrome for years now.

Diagram of energy crisis hypothesis diagram, very simple.

Over-simplified diagram of the energy crisis hypothesis, which occurs in a tiny patch of muscle. Right or wrong, it’s been kicking around for a decades now.

This picture has always been just an educated scientific guess. “The feedback loop suggested in this hypothesis has a few weak links,” wrote Dr. David Simons, a prominent trigger point researcher. (And some skeptics have been a lot more critical than that.)

However, some 2008 research may have firmed up the theory…

Ingeniously measuring muscle knot molecules

Starting with a simpler study in 2005, and then a more thorough one early this year, a group of scientists using “an unprecedented, most ingenious, and technically demanding technique” have reported that there really are irritating metabolic wastes floating around the neighbourhood of trigger points: “… not just 1 noxious stimulant but 11 of them,” Simons explains. “Instead of just a few noxious chemicals that stimulate nociceptors [pain sensors], nearly everything that has that effect was present in abundance.”

The researchers analyzed tissue samples from in and around trigger points and compared it with samples from healthy muscle tissue. The differences were significant.

If they are right, the tissue of trigger points appears to be just rotten with irritating molecules: molecules associated with inflammation, with pain, and with immune function.

Does your body feel like a toxic waste dump?

It may be more literally true than you realized. A muscle knot is a patch of surprisingly polluted tissue: a nasty little cesspool of waste metabolites. No wonder they hurt. It could be more like being poisoned than being injured.

Feel the burn! Are muscle knots acidic?

Personally, I was pleased to see evidence that trigger points are also strongly acidic. I guessed that this might be the case in about 2002. (The pioneer of trigger point research, Dr. Janet Travell, had already suggested the same thing, but I didn’t know it then.) I often told my patients that trigger points were “acidic,” because it seemed likely to be true and because … well, it just sounded good, I guess. (In those days I was not as scientifically literate as I am today, and I hadn’t noticed that I was being intellectually dishonest, presenting a sketchy theory as though it were a meaningful fact.)

Fortunately, this new research now gives some support to that old opinion. (And Dr. Travell’s.) It doesn’t prove it, but it’s certainly noteworthy.

Trigger points really are strongly acidic which means that, for instance, it is actually plausible that deep breathing — which lowers blood acidity — could be relevant to treatment. One of the possible goals of massage therapy is to “flush” trigger points by pushing stagnant tissue fluids out, sometimes called “blanching.” Perhaps if blood arriving in the area is significantly less acidic, the trigger point will recover more easily? It’s plausible.

On the other hand, all that could be wrong

We shouldn’t accept the results of this experiment at face value simply because it seems to confirm an idea much beloved by massage therapists. Rubbing trigger points is probably not “detoxifying” — that’s not what this research means, even if it’s correct. Which it isn’t necessarily.

In a complicated and very technical experiment, it is all too easy for researchers to find the result that they want to find. Rubbing trigger points is probably not “detoxifying” — that’s not what this research means, even if it’s correct. I think that’s exactly what happened in a popular study supposedly showing that massage reduces inflammation, a related idea. This is why independent confirmation from other experiments is always essential. To date (2015, as I’m doing a maintenance edit) this research has not yet been duplicated as far as I know.

The experiment has been criticized and dismissed by some experts. So take it all with a grain of salt for now.

More muscle knot reading

Professionals are strongly encouraged to read David Simons’ analysis of both the new evidence about the chemistry of energy crisis in trigger points, as well as another new scientific article on the use of magnetic resonance elastography (MRE) imaging — a promising new way of taking pictures of muscle knots.

Simons writes that this technology “may open a whole new chapter in the centuries-old search for a convincing demonstration of the cause of MTP symptoms.”

Unfortunately, most casual readers will be stumped by Simons’ thick scientific jargon. For much more readable analysis information about muscle knots, see my tutorial for patients and professionals:

Trigger Points & Myofascial Pain Syndrome

Myofascial trigger points — muscle knots — are increasingly recognized by all health professionals as the cause of most of the world’s aches and pains. This detailed tutorial focuses on advanced troubleshooting for patients who have failed to get relief from basic tactics, but it’s also ideal for starting beginners on the right foot, and for pros who need to stay current. 176 sections grounded in the famous texts of Drs. Travell & Simons, as well as more recent science, this constantly updated tutorial is also offered as a free bonus (2-for-1) with the low back, neck, muscle strain, or iliotibial pain tutorials. Add it to your shopping cart now ($19.95) or read the first few sections for free!

About Paul Ingraham

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

I am a science writer, former massage therapist, and assistant editor of I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook and Google, but mostly Twitter.

What’s new in this article?

All updates are logged to demonstrate a long term commitment to quality, accuracy, and currency. moreWhen’s the last time you read a blog post and found a list of 30 updates and upgrades made to that page over a period of many years? Like good footnotes, this sets apart from other websites and blogs. This transparency is in the spirit of the editing history available for Wikipedia pages. Although footnotes are more useful for readers, the update logs are important: they demonstrate an auditable long-term commitment to quality and accuracy. Although they are “fine print,” I think they are more meaningful than 98% of the comments that most Internet pages waste pixels on. I log any change to articles that might be of interest to a keen reader. Historically, I only logged major updates for popular and controversial articles, and countless minor updates for other articles were not logged. Logging of all updates for all articles started in 2016.

Minor editing (just enough to constitute a meaningful improvement.)

Added acknowlegement of scientific controversies and uncertainties during a period of very high traffic to the article.