SaveYourself.ca • Sensible advice for aches, pains & injuries
Muscles cells and the sarcomeres insides them, the potent little bundles of protein that power muscle tissue. Artist unknown, unfortunately.
EXCERPT This page is an excerpt from a much more detailed tutorial about myofascial trigger points (muscle knots), which creatively explores many other aspects of the science of trigger points.
What’s in a knot? An unholy clump of contracted muscle sarcomeres living in a swamp of garbage molecules, waste metabolites: “… not just 1 noxious stimulant but 11 of them.”1 Sarcomeres are the thing: understand sarcomeres and you can make sense of muscles knots. This is absolutely essential for any patient determined to really understand his or her own trigger points, and any therapist who is serious about providing skilful and rational trigger point therapy.
Sarcomeres are the microscopic engines that power muscle tissue, and misbehaving sarcomeres are at the heart of every trigger point. If you understand “sarcomeres,” four important characteristics of trigger points in particular will become clearer and easier to understand:
All of these classic trigger point qualities are due to the nature of sarcomeres and their complex interactions. So, what’s a sarcomere, and what does it do?
… many of the flaws in our ‘design’ have a common theme: They arise primarily from evolutionary compromises ...
Downside of Upright, by Jennifer Ackerman, pp126–145
Sarcomeres are the smallest functional unit of muscle physiology, a molecular-scale structure almost like a microscopic muscle itself. Muscles contract because sarcomeres contract.
A trigger point is a patch of tightly contracted sarcomeres. The dysfunctional sarcomeres contract so strongly that they begin to choke off their own blood supply. This causes a build up of waste products that aggravates sensory nerve endings and causes yet more clenching — a vicious cycle called “metabolic crisis.”
Compared to a muscle cell — which is already mind-bogglingly small, you understand, about 10,000 of them across the width of a fingernail — a single sarcomere is like a grain of wheat in a silo.2 On the other hand, sarcomeres are pretty large as molecular-scale structures go. Every sarcomere is a tidy little package of well-organized proteins, and proteins are massive molecules generally, and sarcomere proteins are big even for proteins. If you were the size of a water molecule, you could wander around inside a sarcomere like a mouse in Grand Central Station.3
We do not have a good understanding of how sarcomeres do what they do. People who make a living studying these things face the possibility of never really understanding their subject, of never even seeing a live specimen doing its thing — live sarcomeres cannot be directly observed.4
Fortunately, we do know what they do. We know they make the world go round. More accurately, they make us go around the world. And they also make us hurt.
Sarcomeres are long and thin. Wrap a few hundred of them together like a bundle of firewood, and then line that bundle up end to end with a few thousand other sarcomere bundles, and you’ve got yourself a single muscle cell or fibre. Every muscle consists of many muscle fibres, and therefore of many millions of sarcomeres.
The overall structure of a sarcomere is easy to describe: overlapping chains of proteins, like the tines of two forks meshed together. To contract the sarcomere, the proteins grab onto each other and pull, increasing the overlap of the tines. To relax, the proteins “just” let go.5
Sometimes isolated patches of sarcomeres go into spasm independently of the rest of the muscle. We know the general physiological conditions that provoke this change — cold, overstretch, stress, trauma, pain, fatigue — but exactly why these things cause some sarcomeres to hypercontract basically remains a mystery. For whatever reason, the proteins grab onto each other, start to pull … and will not let go. The tines of the fork jam tightly together, completely overlapping and even overshooting each other partially, like interlaced fingers.
This tutorial isn’t a sarcomere tutorial. There are many, many descriptions of sarcomeres out there. This is a primer for beginners, and a refresher course for professionals. I do want you to appreciate just how weird and wonderful sarcomeres are, but what we’re really interested in is how sarcomeres have a starring role in your muscle knots.
Trigger points are like pimples — everyone has at least a few, and everyone gets a bad one every now and then. Knowing what makes them tick is great “owner’s manual” knowledge!
To continue reading about the science of sarcomeres, see the full trigger points tutorial, Save Yourself from Trigger Points & Myofascial Pain Syndrome In the full version, you’ll learn about why pressing on patches of stuck sarcomeres “hurts like hell but feels like heaven,” why it tends to make people say funny things, and why contracting muscles with trigger points like trying to pull away from an intersection in third gear. It’s all in the complete tutorial. Buy it now ($19.95) or read the first few sections for free.
This important paper demonstrates that the biochemical milieu of trigger points is acidic and contains a lot of pain-causing metabolites: good evidence in support of the energy crisis theory of trigger point formation and/or perpetuation. It’s an improvement on an earlier paper from 2005 (Shah), with improved methods. It is cogently summarized by Simons, and in my short article Toxic Muscle Knots.
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