Trigger points are traditionally thought to be tiny muscle knots or connective tissue adhesions that cause the sore spots that you may often feel when you press on certain areas of your body, such as your calves or upper trapezius.

Trigger point therapy is a type of massage technique that is supposed to help alleviate the symptoms or even “get rid of” trigger points. 

Although many people find some relief in trigger point therapy, the mechanisms of how it works is as uncertain as most types of massage. Even the nature of trigger points and myofascial pain syndrome is still as murky as a cup of boba milk tea, despite more than 30 years of research. 

Debate around this topic can get heated like the dress color illusion or Yanny or Laurel audio illusion. Proponents of the existence of trigger points claim that trigger points are the cause of myofascial pain syndrome. These sore spots are usually caused by overuse of the muscles where the muscles fibers stay contracted or direct trauma to the muscles.

By applying certain manual therapy techniques, needling, and/or trigger point injections, a manual therapist can “remove” trigger points or at least reduce the pain to get you back to doing your daily activities. 

But there’s a lack of quality evidence that such trigger points exist, as many critics pointed out. Instead of blaming muscle knots or connective tissues, the soreness likely stems from a combination of neural, immunal, and endocrinal factors, as some established pain theories suggest. 

So how can we make sense of this? Is trigger point therapy any different than other types of massage, like Swedish or deep tissue massage? Do you even need trigger point therapy because the nature of trigger points and myofascial pain syndrome are still uncertain?

If you’re a massage therapist, should you even invest in learning trigger point therapy? Let’s take a look at what the evidence says.

What causes trigger points?

The best hypothesis to explain the nature of trigger points is the energy crisis model (or hypothesis) that was proposed by Dr. Janet Travell in the 1940s. She defined it as “a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band [of muscle].

The spot is tender when pressed and can give rise to characteristic referred pain, motor dysfunction, and autonomic phenomena.” Since then, countless modalities have emerged, claiming to directly treat trigger points.

Basically, the hypothesis says that if a muscle fiber is contracted for too long, trigger points can form and myofascial pain develops. In an editorial published in 1981 in Pain, Travell and Rinzler wrote that when a muscle fiber is contracted under stress, (such as in weight lifting or working at a desk job with your neck forward), this causes the sarcoplasmic reticulum of a muscle cell to release calcium ions to activate the muscle fiber contraction with the help of adenosine triphosphate (ATP), the energy currency that fuels our body’s cells.

They wrote that when this happens to a group of bordering muscle fibers, the process can produce a “palpable, tense band of fibers.” 

trigger points energy crisis model

Image: Nick Ng   Background image: Berkshire Community College Bioscience Image Library

Prolonged contractions would produce metabolites, which are end products of cell metabolism. Some of these metabolites are acidic, which can sensitize muscle nociceptors and reduce blood flow in the local area. The state of the muscle fibers would be similar to rigor mortis. 

This brings about a “vicious cycle” where the sacromere of the muscle fibers shortens because there’s a lack of ATP and too much calcium ions.

But the calcium cannot be removed because there’s no ATP present to help release the contraction. Travell and Rinzler wrote that the calcium “should eventually diffuse away,” and there may be something else that causes the calcium to linger. This is where the energy crisis hypothesis had gotten its name. 

Gerwin, Dummerholt, and Shah expanded Travell and Simons’ work in a 2004 paper by describing the role of various factors that play in the energy crisis hypothesis, such as eccentric and maximal muscle contraction, acetylcholine, pH level, and various chemicals in the muscle tissues. When the jargon of the expansion is simplified, it sounds similar to what Travell and Simons wrote in 1981. 

Trigger point therapy debate

Before asking whether trigger point therapy works or not, we should understand the debate about the nature of trigger points and myofascial pain syndrome. This can help us decide which treatment is the best or if treatment is even necessary.

“Are these nodules not so much the cause of myofascial pain, but rather normal variations in muscle tissue that are merely coincidentally located over areas of discomfort? With such inconsistencies, this raises the question of whether trigger points exist or not.” ~ Nick Ng

Muscle knots

This can be a tricky discussion because almost everyone has experienced a painful area on their body and instinctively pressed on it to find it temporarily relieves the discomfort. We can agree changes in tissue can often be felt in areas where pain is present when it moves from a state of tension to relaxation and vice versa. These tight spots are what are commonly referred to as muscle knots

Muscle tissue can feel tight and wiry for many reasons, and sometimes for no apparent reason at all. The term muscle knots, or “knots,” is a useful and universally understood way to communicate how that tension may feel both internally and externally.

But it’s critical to understand that the tissue itself does not get “knotted” in the literal sense. Knots are not the same as muscle spasms because muscle spasms involve a sudden contraction of an entire muscle. This is what happens with a charley horse, whereas knots are a small, partial contraction of a few fibers in a muscle segment.

The phenomenon of knots and trigger points is complex, so it’s helpful to summarize it into “knots” as long as we understand that the term isn’t an accurate representation. To translate it more accurately and simply, knots can behave like a group of microscopic zippers. The contractile elements of the muscle zip closer together and remain active in a specific area of that muscle, and this can sometimes cause it to feel tight or stiff. 

They get into this state because the nerve responsible for stimulating them is firing in a way that is causing a cluster of them to zip closer together. So a knot cannot exist without a signal from a nerve. 

This is why receiving a massage to help “release knots” isn’t the same as mechanically untangling ropey-feeling muscles, though it may certainly feel that way on the receiving end.

It’s more accurate to say that the stimuli from the massage is sending a signal to a nerve or a bundle of nerves. Then the nervous system processes the touch stimuli being received. This can tell the nerve that is communicating with the knot to unzip a bit, which helps the muscle fibers relax. 

The key is to figure out why the nervous system is generating a knot in the first place. Certain knots might be associated with pain and others are not at all. Although a knot may be associated with discomfort, often these nodules may serve a beneficial purpose. They can support muscle patterns that are commonly used to execute movements or tasks. 

For example, a golfer’s dominant side will likely have more knots than the non-dominant side because there’s more habitual activity in those muscles the body has been conditioned to execute. This is also why knots may or may not be associated with discomfort. People will tend to notice knots more only while they are experiencing aches, even though the nodule might still be present during pain-free periods.

If the muscle fibers aren’t knotted in any way, mechanically pushing into these areas by some external means, usually manually or with a tool, doesn’t technically “release” the area in the way we might imagine. How we think of the mechanism makes a difference in how such issues may be addressed more effectively. 

No consistent diagnosis

Diagnosis of myofascial pain syndrome has been shown to be inconsistent among different manual therapists. A group of British researchers, led by Dr. Elizabeth Tough from the University of Exeter, reviewed 93 qualified research on the diagnosis of myofascial pain and trigger points.

They said the reliability of the diagnosis is “varied and inconsistent” because of a lack of “gold standard” in diagnostic criteria which allows clinicians to “accurately and consistently define a case of [myofascial pain].” They found 19 different criteria to diagnose a trigger point. That’s a lot of inconsistencies.

Common diagnostic criteria include “tender spot in a taut band,” predicted pain referral  pattern on tender spot palpation,” and “local twitch movement.” However, only 15 percent of the researchers used these factors to diagnose.

Trigger points are usually asymptomatic, meaning that these tight nodules are also found consistently and abundantly in people who don’t report any type of musculoskeletal pain.

This raises the question: are these nodules not so much the cause of myofascial pain, but rather normal variations in muscle tissue that are merely coincidentally located over areas of discomfort? 

With such inconsistencies, this raises the question of whether trigger points exist or not. 

Breaking fascia and tissue adhesions

Fascia is another tissue assumed to be involved in myofascial pain syndrome. “Myo” is the Greek root word for muscle, and fascial refers to fascia. This is the connective tissue layer below the skin layers that also covers the muscles and other tissues.

In manual therapy professions, there’s the almost ubiquitous belief that tight or wound up fascia is also a contributing factor in myofascial pain syndrome and movement restrictions.

In some schools of thought, it’s also believed that the fascia can get “stuck” or “glued” to muscle tissue. This is referred to as an adhesion and is also often blamed for myofascial pain and decreased range of motion.

There are countless approaches aimed at releasing the fascia or “breaking up adhesions,” but there’s a more accurate understanding of how the body works. With the updated data, the idea that fascia is responsible for myofascial pain syndrome is becoming recognized as implausible

Soft tissue manipulation does not generate enough force to permanently stretch or change fascia. One study by Dr. A Joseph Threlkeld found that in order to create permanent change in the tissue, you need to break collagen fibers. This type of force is capable of causing extreme injury and requires thrust techniques outside the scope of practice of massage therapists. Even that approach is questionable.

The idea of breaking up adhesions has also come under fire. Dr Greg Lehman said, “I don’t know what an adhesion is. It makes no sense. If it is scar tissue, then there is no way you are breaking it up with your hands. Not possible. Surgeons use knives for this. Is it some stickiness between tissues? Well, don’t worry about it. When you move, warm up, or strength train, it will go away. Welcome to viscosity land.”

Although the terms “release” and “break up” are easy to visualize in regards to attributing pain or movement restrictions to fascia and adhesions, they are inaccurate when it comes to understanding myofascial pain syndrome.

Also, this incorrect way of thinking has led to unnecessary post-massage soreness for many where manual therapists use unnecessary, and sometimes injurious, amounts of pressure that don’t affect fascia or break adhesions in the way they were taught.

This isn’t to say that the manual approaches do not work or help, but rather to fine tune the explanation as to why they may. In the past 40 years, much more has been discovered about the body, and so has more effective treatments.

There are better explanations for what happens when the manipulation of tissues helps someone feel better or improve their range of motion. One such explanation is the biopsychosocial model of pain, where pain is a complex and personal experience based on biological, psychological, and sociological factors. 

Cinderella hypothesis inconsistent with new evidence

The energy crisis model explains how trigger points and myofascial pain develop, but it doesn’t tell us why a “normal” muscle would develop these symptoms. The Cinderella hypothesis is the current narrative behind why trigger points and myofascial pain exist.

It basically says that “low-level, static exertions” of muscles—particularly type I slow-twitch fibers—can cause the symptoms of myofascial pain. Because these muscle fibers are constantly contracted and “metabolically overloaded,” they are more likely to form trigger points, according to Kadefors et al

One early study in 1999 by De Lucas and Westgaard. found that low-level motor units in the upper trapezius in a shift-like pattern rather than in a hierarchy proposed by the Cinderella hypothesis. When these tonic muscle fibers stay contracted for a long time, some of these fibers take turns to maintain the contraction. One group rests while the other works. Two years later, they published another paper that seems to confirm the shift pattern. 

These findings led Minerbi and Vulfsons in 2017 to propose the “shift model” that could better explain how tonic muscles activate and contract. This new model postulates that muscle fibers take turns activating so that one set rests while the other works.

Energy crisis model: has it been proven?

Another debate is about the nature of the energy crisis hypothesis. Although the mechanism behind his model sounds plausible and reasonable, Quinter, Bove, and Cohen stated in a 2014 paper that “there is no experimental evidence in support of the hypothesis.”

They pointed out a study by Shah et al. that both symptomatic and asymptomatic subjects had similar levels of inflammatory markers, an indication that the “energy crisis” exists. They said that is no evidence in the increase of certain motor neurons’ activity in chronic muscle pain.

In one Australian study by Fazalbhoy and Birzneks, they found that long-term stimulation of certain afferent nerves “fails to excite fusimotor neurones and increase muscle spindle discharge.” Thus, the energy crisis hypothesis “has no functional basis for the development of myalgia in human subjects.” Another study by Birzneks et al. found similar conclusions. 

Alternatively, Quintner et al. suggest that it is the sensitization of the axons of the nerves, not muscle pathology, that is possibly the source of the inflammation, which can help explain the underlying problem. 

Dommerholt and Gerwin refuted the criticism by pointing out some problems with their argument, such as the faulty usage of the terms “hypothesis” and “theory,” low pH level in tissues with myofascial pain, and the nature of latent trigger points. 

And perhaps trigger points don’t really exist—no more real than a unicorn. As physiotherapists Adam Meakins and Asaf Weisman stated in a letter to the editor in Pain Medicine, “One can describe a unicorn in great detail, but that alone does not mean it exists in the real world.” Thus, they suggest that researchers and clinicians should focus on more plausible explanations about the myofascial pain phenomenon.

As recently as 2019, the debate continues

Palpatory reliability: disagreements among practitioners about what they touch

If you have 100 therapists trying to define what criteria makes up a trigger point or myofascial pain, you would likely have 10 to 20 different opinions. Research in the last 20-plus years reveals so. 

One of the first critical systematic reviews found that the reliability of myofascial pain diagnosis is “less than chance”—no better than a coin flip.

This is based on nine qualified studies based on eight articles that examined symptomatic and asymptomatic patients. The researchers identified major reporting problems in how trigger point research was done, such as lack of blinding of the therapists to clinical information and lack of agreement on what the diagnostic criteria were. 

If such diagnosis has a low reliability and a huge room for error, “an otherwise effective treatment may fail because it is being applied to patients who do not have the condition,” the researchers emphasized. 

In 2017, another systematic review followed up on the trigger point literature, and they found similar results. There was still no “gold standard” of diagnosing myofascial pain or identifying trigger points, and the reliability is still no better than a coin flip. 

In reference to trigger point injection with the low reliability, the researchers asked, “How certain am I that I am actually injecting a [trigger point]?” 

Based on seven qualified studies that examined 23 conditions among 406 patients with nearly 1,500 observations, Rathbone et al. found that there’s a “moderate” level of agreement among the studies, but that may be an “overestimation” because of a wide range of confidence intervals in the data. 

Like the previous review, there are issues with how the experiments were set up, such as non-randomized sampling, selection bias, and unclear reporting of how the researchers were blinded. Identifying tenderness and pain reproduction ranked the highest reliability, but that doesn’t mean trigger points cause pain.

Thus, the evidence questions on how reliable and valid are treatments of myofascial pain and the mechanisms behind trigger points, and patients (and taxpayers) are paying a lot of money for such treatments. But how did the ideas behind trigger points and myofascial pain started?

How did myofascial pain syndrome influence trigger point therapy?

The energy crisis model is based on earlier works of physicians and researchers who studied rheumatism and muscle and joint pain. Guillaume de Balliou (1538-1616) was one of the earliest physicians who had written the first books about arthritis and rheumatism that described symptoms of patients. These symptoms include full-body pain, especially around the joints, very little or no fever, and “‘feelings’ of burning heat.”

Another physician was Dr. Ralph Stockman (1861-1946), a Scottish physician who described the symptoms of chronic rheumatism that can be “felt quite plainly and are painful on pressure.” 

He also described “nodules” and “fibrous indurations”—terms that preceded the term “trigger points”—on the superficial layer of muscles that sometimes felt like a “chain of small-shot or beads running along the side of a muscle or aponeurosis or under the skin.”

Although he didn’t report the nature of these nodules, he suspected that microbes play a role in the symptoms since patients often had a “sore throat” with chronic rheumatism. Today, this is identified as strep throat

Around the same time Stockman’s paper was published, a British neurologist, Sir William Richard Gowers (1845-1915), lectured about lower back rheumatism at the National Hospital for the Paralyzed and the Epileptic in 1904.

He described “looser cellular” tissues that may be inflamed from septic or other causes as cellulitis, and this should be changed to “fibrositis” because of the “inflammation of the fibrous tissue” that are chronic in nature. 

He further described such pain that “may transfix the sufferer in a moment, and make any movement impossible, usually occurs on the first movement after a period of rest,” such as the first movements in the morning. However, the inflammation of the fibrous tissues idea was “discredited as biopsy data did not substantiate an inflammatory pathology,” according to Shah et al.

Other physicians had proposed other underlying causes of rheumatism, such as infections, environmental factors, microtrauma, and psychological factors, as suggested by British physicians Copeman, Ellman, and Kersley in 1947.

In 1939, British physician J. H. Kellgren produced what appears to be an early version of the trigger point charts that we often see in some massage practices. By injecting subjects with a small amount of a saline solution to a spinal ligament, Kellgren mapped the areas where the subjects reported to experience pain.

These ideas served as some of the foundations to Travell and Simon’s work in the mid-20th century, which led to the writing of the familiar red books and trigger point therapy chart. 

Travell Simons trigger point book

Photo: GBACKSTROM, Wikimedia Commons

How does trigger point therapy work?

Pain is a highly complex phenomenon and evidence that touch, in general, can have powerful relaxation and analgesic effects. Although trigger point therapy doesn’t untangle muscle knots, release fascia, or break up adhesions in the literal or mechanical sense, it can certainly still offer relief.

The processes by which relief is achieved can be better explained with concepts updated over the past 20 years. These give us more accurate knowledge about the mechanisms of pain, which are based in the nervous system and not muscle tissue, as was proposed by the trigger point model in the 1940s.  

One of these explanations can be found in the gate control theory of pain, which was later expanded into the neuromatrix theory of pain. These explanations fill in the gaps left by the more simplistic, yet inaccurate trigger point model. These studies reveal that pain is not being generated by or from the tissues, but is rather an interpretation of any stimulus that might be coming from the nervous system. 

Oftentimes, these signals can be ignored if the brain doesn’t consider them a threat, which is why some nodules may correspond to sites of pain while others do not. Tension in and of itself is not “bad.” A certain amount of tension is necessary to keep us aware, upright, and engaged in activities throughout the day.

Tension in the form of nodules often presents in areas that require additional muscular support or readiness. This can be seen in the example mentioned early with the golfer who likely has more nodules present on their dominant side.

If we consider the effects of how psychological stress translates into neurological impulses, it’s easier to understand why pressure from daily life can also transform into physical tension that has nothing to do with muscular dysfunction or fascia. 

The nerve impulses that go out into the tissues, can tell muscle fibers to contract or to return to a relaxed state. They can also report information about the tissues and the environment back to the brain.

This input and output of information is a two-way highway from the nervous system out into the tissues, and vice versa. Touch can be one of the ways helpful information is introduced and transformed into a stimulus.

So when an area is pressed, the good feeling touch sends a message to the nerve(s) associated with the muscle pain. If the brain interprets the tissue beneath is supported, this often allows the area to lay down its “guard” and “let go.” 

If someone is experiencing myofascial pain syndrome, it is crucial to consider all other factors of life that might be contributing to their experience of pain. Outside of any obvious tissue stressors, such as strenuous use of the body as well as not having enough activity, factors such as psychological stress, beliefs about what might be causing pain, depression and anxiety, and sociological factors like economic status must be taken into account.

All of these offer a clearer picture as to why one person with a trigger point in their calf experiences pain, when someone with a seemingly similar presentation does not. 

There has been a recent link discovered between the nervous system, immune system, and endocrine systems that might also be a factor parading as myofascial pain syndrome. These combined systems have been termed the neuroimmunoendocrine system, which adds even more complex layers to myofascial pain syndrome.

How to perform trigger point therapy

Trigger point therapy often consists of pushing, squeezing, or compressing over an area that feels tight or painful. Pressing directly into the muscle tissue through the skin is known as ischemic compression and can sometimes relieve muscle tension and discomfort.

Trigger point charts often associate common areas of pain or discomfort and they are often used by therapists as a visual aid or reference. These charts illustrate general patterns and regions of pain that may seem to stem from a particular nodule.

However, these trigger point charts are not real-life representations of nervous system referral patterns, as these present uniquely in individuals. Even so, they can be helpful for beginners who are getting acquainted with musculoskeletal pain presentations, but these ideas should not be considered definitive or set in stone.

A therapist will zero in on the area where pain is felt using ischemic compression. This involves maintaining comfortable pressure from three or more seconds at varying degrees and angles. This form of therapy can also be used on oneself by manually pressing into the area of discomfort.

This can also be done with the aid of a tennis ball or a similar object. If you’re unsure about where to apply compression, a trigger point chart can be a good place to start. One can address the areas highlighted on the chart and modify as needed. It’s true that referral sensations may be experienced, and that is normal. These sensations can change or seem to “move around.”

When applied correctly, this type of compression appears to slightly whiten the skin beneath it. This happens because blood is temporarily pushed out of the vessels. The idea behind this approach is that when fresh blood rushes back in, it supplies the nodule with oxygen which in turn helps the trigger point “release.” 

One of the most common areas where trigger points are present is along the upper trapezius muscle. This is the area most people point to when they say they feel shoulder tension. It is an instinctual area to reach for and want to squeeze when stress is felt. 

Trigger point therapy is also used in the area of the lower back and gluteal region to address back and hip pain. This is an easy to access area for self-massage.

Many people lay on a tennis ball or rolled up sock placed over the area and achieve pressure that way. Sometimes a foam roller is used for a broader point of contact. Rolling the object over can also be done if laying on top of gives too much pressure.

The tissue in these areas are more dense and can absorb more pressure, but that is not always the case. It can also be sensitive and reactive, so it’s important to move slowly and gently.

The idea with any trigger therapy approach is to find what feels like the target point where a painful sensation might come from and apply direct pressure over it. On the hamstrings, there’s usually a responsive area midway between the back of the thigh. Therapists should go easy because it’s very easy to elicit pain with extra pressure, even though the area was previously unbothered.

It’s also good to consider that there are alternate approaches to trigger point therapy, such as dermoneuromodulation, that may prove more effective if ischemic compression isn’t producing the desired or longer lasting outcome.

How to find the best trigger point therapy near you?

Despite the lack of clear evidence about the existence of trigger points, trigger point therapy itself may still provide pain relief of many people because it’s a form of physical touch. Like most forms of massage like sports massage, trigger point therapy doesn’t need to be painful. If your massage therapy insists on such painful treatments, find another therapist.

Your therapist should be evidence-informed and licensed or certified. This means that they should be practicing based on the best evidence available so you can be well-informed and not receive treatments that can be harmful. 

Some countries have a directory that lists who is a qualified massage therapist near you. For example, in the U.S., there is the American Massage Therapy Association, and in Canada, there are the Registered Massage Therapists Association of British Columbia and Registered Massage Therapists’ Association of Ontario

If you know the therapists’ name or their identification number, you can see the status they are in, such as whether their certification or license is active, suspended, revoked, or otherwise. The California Massage Therapy Council has one such feature. 

While the debate about the nature of trigger points and myofascial pain continues, rest assured that it doesn’t necessarily negate the benefits of trigger point therapy and other types of massage. Existing pain theories can still help guide how massage therapists do their work and communicate with you. 

Remember that there’s a difference between the hands-on touch of trigger point therapy and the narrative behind how it works. If you find pain relief in trigger point therapy from a great massage therapist, then that’s good news!

But if you’re curious and want to dig deeper in why it works for you, well, the current body of evidence is steering toward a larger scope of why you feel pain—which was mentioned in the realm of neuroscience, immunology, endocrinology, psychology, and even social sciences.

Given the evidence so far, take trigger point and myofascial pain explanations with caution.


“Trigger points are nowhere near as bad as a lot of common pseudoscience and quackery gets, but they certainly do fall well short of ‘proven’ and well-understood. At worst, they may even be a bad idea—a legitimate misunderstanding, an idea that was reasonable 20 years ago but which now needs to be retired or heavily revised.” ~ Paul Ingraham, The Complete Guide to Trigger Points and Myosfacial Pain

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A native of San Diego for nearly 40 years, Nick Ng is an editor of Massage & Fitness Magazine, an online publication for manual therapists and the public who want to explore the science behind touch, pain, and exercise, and how to apply that in their hands-on practice or daily lives.

An alumni from San Diego State University with a B.A. in Graphic Communications, Nick also completed his massage therapy training at International Professional School of Bodywork in San Diego in 2014.

When he is not writing or reading, you would likely find him weightlifting at the gym, salsa dancing, or exploring new areas to walk and eat around Southern California.

tania velasquez
Tania Velásquez, LMT
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Tania Velázquez teaches orthopedic and sports pathologies, kinesiology, and the advanced practical class at the New York campus of Pacific College of Health and Science and at Pinpoint Education. She graduated from Florida Academy of Massage in 1994. Stuff that interests her include urban gardening, hapkido, home-cooking for guests, and exploring non-verbal communication and its intricacies and power behind the words we choose to use in practice.