Trigger points. For something so vital to the career of every practicing massage therapist, surprisingly little is truly understood about these mysterious “knots” in muscle tissue.
Depending on whom you ask, you’ll probably get a different response as to what they are, where in the body you’ll find them, and how to properly treat them.
This, of course, is only if they think trigger points exist at all.
How is it that something so integral to our profession, has so many different opinions as to what they are?
Are they a restriction within the fascia that surrounds the muscle tissue? How about a muscle cramp, just on a much, much smaller scale?
Could they be nothing more than inflammation, pushing on a nerve ending, producing the infamous referred pain patterns?
Or could trigger points be a product of muscle exhaustion?
Some, would argue, that it really doesn’t matter what they are. If our clients leave our treatment table feeling better, and are experiencing positive results regarding pain and range of motion, isn’t that the most important thing?
Before we can attempt to answer this question, it might be a good idea to see how we got here in the first place.
Causes of Trigger Points?
Muscular pain without traumatic injury isn’t anything new to the medical community.
Prior to the 1950s, it was thought to originate from inflammation of the connective tissues, such as bone and fascia. When this was shown to be false through biopsies of tissues, a new culprit was needed to explain the enigmatic pain.
In 1983, after decades of passionate and difficult work, former White House physician Janet Travell, MD, published Myofascial Pain and Dysfunction: The Trigger Point Manual, with coauthor and former Air Force physician David Simons, MD. This highly detailed text, consisting of two separate volumes, quickly became the authority on myofascial pain.
It’s from their work that we get the definition of a myofascial trigger point that is still taught today: a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. The spot is tender when pressed and can give rise to characteristic areferred pain, motor dysfunction, and autonomic phenomena.
This definition, while useful, is merely a description, and unfortunately doesn’t provide us with the causes of trigger points.
It was this desire to find a cause that led to decades of research into trigger points, as well as a considerable dose of speculation.
In March of 2015, John L. Quintner, Geoffrey M. Bove, and Milton L. Cohen published an article in the medical journal, Rheumatology titled, “a critical evaluation of the trigger point phenomenon.”
The authors showed that the evidence supporting the various theories behind trigger points were shaky at best, and flat out wrong at worst.
So, what are these issues?
To have this conversation, we first need to make sure we understand the basic anatomy and physiology of how muscles contract. Only then, can we begin to see where the various theories behind trigger points start to break down.
How Muscles Contract
It probably comes as no surprise to you, but the decision to contract skeletal muscle starts in the brain.
To be specific, it begins in an area in the back of the frontal lobe, called the primary motor cortex. This highly folded region of the brain contains the nucleus and various other organelles of each neuron responsible for skeletal muscle contractions.
Right now, as you’re reading this, neurons are firing from your motor cortex, and making their way to your extrinsic eye muscles, allowing them to dart back and forth as you read.
Let’s say, for the sake of science, that you wanted to wiggle your big toe up and down. To do this, a neuron located in the motor cortex would fire, sending an electrochemical cascade down its axon, towards the big toe.
Before it gets there, it must make its way through the core of the brain, and then head down the entire length of the spinal cord. This highly specific pathway, called the corticospinal tract, resides in the white matter of the spinal cord, on both the left and right sides.
When the neuron arrives at its correct spinal level, the signal is transferred to a second neuron, which leaves the spinal cord, and travels through a series of nerves as it descends the body towards its target muscle, the extensor hallucis longus.
It’s here that the neuron meets up with the individual muscle cells, at what’s called the neuromuscular junction.
Without getting overly specific with the biochemistry that occurs here, the neurotransmitter acetylcholine is released from the end plate of the neuron, causing calcium to be released into the cell, in an area called the sarcomere.
The sarcomere consists of several types of structural proteins needed for muscle contraction. The primary ones are myosin, actin, troponin, and tropomyosin, but several others exist as well.
As calcium enters the sarcomere, it attaches itself to troponin, exposing binding sites on the actin molecules. This allows myosin to attach and perform a power stroke, causing the length of the sarcomere to shorten.
Now, imagine sarcomere after sarcomere, stacked end to end, all shortening together, pulling on our big toe as we wiggle it up and down.
This incredible line of events is what we call a muscle contraction, and the entire process only takes 20 thousandths of a second or less.
Now that we know how muscles contract, let’s discuss two of the most researched theories of myofascial pain.
A Spontaneous Signal
If muscles contract based upon a signal from the nervous system, what happens if the signal becomes sporadic?
Normally, acetylcholine only leaves the end plate if it receives a signal from the motor cortex. However, it’s possible that one of the causes of trigger points is the release of acetylcholine even though no decision to contract the muscle was made.
Using equipment designed to measure electrical activity at the neuromuscular junction, researchers discovered evidence suggesting that trigger points might exhibit spontaneous electrical activity.
If true, the unwanted release of acetylcholine could cause the muscle cell to work at an unsustainable rate, initiating a wide range of symptoms, including those shown to accompany trigger points.
This theory, which seems completely reasonable and is even favored by David Simons, unfortunately begins to break down when you introduce a surprising variable to the mix — Botox.
Botulinum Toxin A, or Botox, is a neurotoxin produced by the bacterium Clostridium botulinum. It’s one of the most lethal toxins known to man, and also happens to be used throughout medical industry in extremely small doses.
Botox works by preventing the release of acetylcholine at the end plate. It enters the neuron, and quickly renders it ineffective, thereby paralyzing whichever muscle the neuron is responsible for.
Researchers injected small amounts of Botox into areas diagnosed to have trigger points and noticed something very peculiar—the neuron stopped working as expected, but the pain and symptoms of the trigger point didn’t disappear.
This is a problem because the symptoms should have disappeared with the Botox injection. The fact that this didn’t happen suggests that while hyper secretion of acetylcholine may play a role in the formation of trigger points, it probably isn’t the cause of them.
An Energy Crisis
Capillaries are the smallest possible blood vessel in the body. Their job is to deliver oxygen and nutrient rich blood to the various tissues, as well as accumulate the many metabolic wastes created by the cells.
As muscles contract, the tension they create squeezes the capillaries that flow inside of them, momentarily obstructing blood flow and delivery to the muscle. Normally, this isn’t much of an issue, seeing that contractions are relatively short lived.
However, if you sit at a computer all day, slouching forward, straining the musculature of the neck and upper back, it stands to reason that the muscles will experience a much longer duration of blood flow blockage than they normally would.
Without blood flow, the muscle cells are unable to gather up oxygen. You may remember from your high school biology class that oxygen is essential to create the energy source of the body, adenosine triphosphate, or ATP.
Without ATP, calcium ions remain inside of the muscle cell, creating a situation of perpetual contraction. This contraction then maintains the obstructed blood flow, and we find ourselves in a feedback loop.
This vicious cycle also causes damage to the cell membrane of the muscle cells, creating a site of injury, and bringing inflammation to the tissue. The inflammation would then compress surrounding nerve endings, creating the typical symptoms found with trigger points.
Again, this theory seems reasonable and intuitive at first glance. Surprisingly, the break down comes in the form of mechanical pressure on the muscle, or massage therapy.
Researchers have discovered that when pressure is applied to a muscle experiencing pain, the overall muscle tone and pain decreases. They also found that when a muscle is experiencing pain, the agonists to that muscle relax, so that tension is reduced upon the muscle experiencing pain.
This runs counter to everything we know about trigger points. In fact, the very definition of trigger points, provided by Travell and Simons, states that the feeling of tenderness should increase upon palpation, not decrease. Yet, not only do we find tenderness and pain upon palpation, we also find tense muscles surrounding the trigger point.
While this evidence suggests that massage therapy is an effective means for muscle relaxation, it doesn’t support the idea of trigger points being the result of an energy crisis. According to this, overall muscle tension and pain should decrease upon pain and tenderness, yet, the opposite is most definitely true.
Where Do We Go from Here?
Massage therapists, like all human beings, are susceptible to biases.
Our profession demands a certain level of knowledge and expertise about treating musculoskeletal dysfunctions and their associated symptoms. (Editor’s note: no matter the clientele, massage therapists should possess a liability insurance policy that covers many modalities.)
When clients come to us complaining of myofascial pain, it only makes sense to treat them with our preferred trigger point method. Then, if our clients experience a positive outcome from the session, it’s easy to assume it’s because of our specific technique, and not from some unforeseen reason.
This, however, is bias trickling to the forefront.
After all, how do you know that it’s from the technique itself, and not just from simply doing bodywork?
I want to be clear—I’m not suggesting that we throw our hands up in the air and give up on trigger points.
Although we may not know what they are, we can still provide our clients with relief, even if it’s only temporary. Evidence shows that massage therapy works in terms of reducing pain and increasing range of motion.
While this may seem like a small part to play, I would argue that it’s one of the most important.
We as massage therapists can provide a sense of rejuvenation to our clients that few other medical professionals can. If our clients feel as though what we’re doing is helping, I see no reason to stop.
I don’t want it to seem that I’m trouncing all over trigger point therapy.
In fact, I personally think that trigger points are something close to the theories we just discussed.
It may even be some combination of both of these ideas, and other theories as well. I personally think that fascia has a large role to play in the formation and maintaining of myofascial pain, but the evidence to support that is far from robust.
So, what are trigger points?
We have no idea!
But that shouldn’t be cause for concern. Instead, we should see this as a puzzle to be solved.
With time and patience, the science will become clearer, and bodyworkers all over the world will be better equipped to tackle these painful little “knots.”
About the Author
Justin Cottle, LMT, teaches Anatomy, Physiology, and Pathology for the Cortiva Institute at the Utah College of Massage Therapy, as well as instructs future EMTs, medical assistants, dental Assistants, Estheticians, Massage Therapists, Structural Integrators, and Yoga Instructors at the Institute of Human Anatomy.
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