Study: "Trigger points, muscle knots, do not exist"

"Trigger points, muscle knots, do not exist". That will kick plenty of massage therapists and therapists in the shins. Although countless treatment methods already exist for muscle knots, there is significant criticism of the basis for them.

In this article I discuss the common theory that forms the basis for current treatments, as well as the criticism from researchers who argue that this theory has not been proven. Have the existence and nature of trigger points, muscle knots, actually been demonstrated? And if so, do practitioners actually know how to find them?

Pseudoscience

A simple example of pseudoscience is the little graphs you see in some commercials. Usually for whiter teeth or something similar. "Clinical research shows that in just three days blah, blah, blah".

While watching a commercial, we know that we should take these kinds of claims with a grain of salt. It is different, however, when researchers, doctors, massage therapists, therapists and hospital pain clinics tell you something. You assume this is not bro-science. You assume that when they say muscle knots can lead to a large number of complaints, this has been researched. You assume, for example, that different practitioners would be able to find the same muscle knots in the same person. After all, how can you treat something you cannot find?

After all, we are not talking about something vague such as meridians and chi, right? That depends on which story you read, and that often depends on which story is told most often. If you search for information about muscle knots, this is probably what you will find:

Muscle knots, trigger points

"Neuromuscular trigger points", or "muscle knots", are contracted and thickened parts of a muscle that can lead to various complaints.

This usually refers to the following symptoms [1]:

• A local, persistent painful and/or irritated point in a skeletal muscle or connective tissue
• The painful point can be felt as a thickening, and stimulating this point, for example by pressing it, can produce a kind of "twitch".
• Touching the point causes pain that can also radiate
• The pain is not caused by nerves
• Reduced range of motion
• Less strength in the affected muscle

Cause of trigger points

Trigger points can be caused both by acute trauma and by the cumulative effect of multiple microtraumas. Especially with the latter, you can think of the effect of strength training, but also of many repeated movements in daily life. Trigger points can also occur in the muscles that control posture, such as the neck and shoulders, which could lead, among other things, to tension headaches [1].

Muscles are contracted consciously and unconsciously. To make this possible, blood is continuously supplied to and removed from the muscles. Under tension, waste products can accumulate locally, causing the tension to increase further in a vicious cycle. Muscle knots are therefore sometimes said to be caused by a "metabolic energy crisis".

The waste products stimulate nociceptors, or "pain receptors". These are the nerve endings that send signals to indicate the presence of harmful substances. Signals that we experience as pain.

Finding trigger points

How do you find muscle knots? In practice, muscle knots are found by a practitioner who searches for them by palpation. By moving a finger with light pressure along the muscle, the practitioner searches for thickened areas with a different consistency from the rest of the muscle [2]. Once found, you would feel this because the point feels painful and irritated. The "twitch feeling", the sensation of a muscle fiber springing away, is often experienced when the finger moves across this point perpendicular to the direction of the muscle.

Trigger points and waste products

Researchers from the National Institutes of Health looked at differences in the presence of various waste products between people with active trigger points and people who did not have them [3]. They measured the levels of several waste products in both the trapezius muscle and the gastrocnemius. Only in the trapezius had active trigger points previously been found in the participants who were then assigned to the "active subjects" group. In this way, they could measure not only the differences between people with and without active trigger points, but also between affected and unaffected muscles.

They showed that people with previously identified active trigger points did indeed have higher levels of several waste products in the trapezius. In those cases there were also more waste products in the trapezius than in the calf muscles, where there were no trigger points. That seems to confirm the negative feedback theory (tension-->waste products-->energy crisis-->more tension). What is strange, however, is that although the calf muscles of the "active subjects" contained fewer waste products than the trapezius in that same group, they still had higher levels than the calf muscles in the "latent subjects". Why would people with muscle knots in the trapezius also have higher levels of waste products in their calf muscles?

We followed a predetermined sampling schedule; first in the trapezius muscle and then in normal gastrocnemius muscle, to measure pH, bradykinin, substance P, calcitonin gene-related peptide, tumor necrosis factor alpha, interleukin 1beta (IL-1beta), IL-6, IL-8, serotonin, and norepinephrine...

...Subjects with active MTPs in the trapezius muscle have a biochemical milieu of selected inflammatory mediators, neuropeptides, cytokines, and catecholamines different from subjects with latent or absent MTPs in their trapezius. These concentrations also differ quantitatively from a remote, uninvolved site in the gastrocnemius muscle. The milieu of the gastrocnemius in subjects with active MTPs in the trapezius differs from subjects without active MTPs.

J.P. Shaw, Rehabilitation Medicine Department, National Institutes of Health

Trigger points and tension

That a muscle knot is under greater tension than surrounding tissue appeared to be demonstrated in 2008 using Magnetic Resonance Elastography (MRE) [4,5]. By using the better-known MRI in a specific way, differences in tension at different locations in tissue can be shown [5,6,7,8]. With this, they showed that stiffness in points experienced as painful can sometimes be as much as 50% higher than in surrounding tissue.

In the image below you can see the result of such a measurement. On the right you see four trigger points, visible as four dark little spheres. On the left you see an enlargement.

The study was mainly intended to see whether using MRE is a good way to detect muscle knots. The researchers still point to technical challenges, but others also see several shortcomings in their research (see below).

Active and latent trigger points

In the studies above, a distinction was also seen between so-called latent trigger points (LTrPs) and active trigger points. Active and latent trigger points both cause a similar pain and twitch response when touched [8].

Active trigger points, however, also cause so-called referred pain. This is pain felt in a different location from the source [9]. A practitioner familiar with trigger points should in many cases be able to trace the source from the location of the referred pain. For many trigger points it has been recorded where they usually produce referred pain [2,8].

Unlike latent trigger points, the pain caused by active trigger points can be persistent. A latent trigger point would only cause pain when pressed, and sometimes when the muscle is used. Active trigger points, however, are said to develop when the circumstances that caused the latent trigger point persist. It is therefore important to address them in time.

"Muscle knot theory has not been proven"

So much for the common story and the studies intended to support it. It is important to realize that the above account of the existence, nature and cause of trigger points is only a theory. It is, however, a theory that is widely supported. Even to such an extent that critics indicate that certain things are wrongly accepted as fact [10].

It is an interesting study in which the development of the current theory is explained [10]. The researchers Quintner, Bove and Cohen state, among other things, that the existence of latent trigger points is barely substantiated. This would merely be an assumption to explain painful points in muscles where no abnormal tissue can be found [11].

Patients themselves often report that they have been helped by treatment of trigger points. According to Quintner and colleagues, however, it is unclear to what extent this is a placebo effect or the experience of other positive effects that have nothing to do with trigger points. I myself think, for example, of reducing tension in the entire muscle and reducing stress that comes with massage. Injecting corticosteroids, whether into trigger points or not, will also relieve other causes of pain complaints because it has an anti-inflammatory effect. Especially if, as is often the case, it is injected together with an anesthetic.

History of the muscle knot

Let us therefore take a step back. Where does the idea of muscle knots come from?

The idea that lesions (abnormal tissue) in muscles lead to complaints dates back to the beginning of the previous century [12,13]. In 1903, "fibrositic nodules" were described, painful little bumps in muscles [13].

David Simons, a researcher who spent more than four decades working on trigger points, predicted in 1976 that these could eventually be found and described better using new techniques [14]. In 1984 he wrote "Myofascial pain and dysfunction: the trigger point manual" together with Janet Travell, which has more or less been accepted as the bible of trigger points. In it, they made drawings of trigger points and their referral areas, among other things [11]. It is often cited and used as "the standard" for working with trigger points. David Simons and Janet Travell are not small names either. Travell was J.F. Kennedy's physician. Besides being a physician, David Simons was also an air force officer who appeared on the cover of Life magazine thanks to his record-breaking high-altitude balloon flight [15,16]. Their words were therefore quickly adopted, while many of their claims were based on assumptions.

Critic and rheumatologist Fred Wolfe therefore devised a simple test [17]. Simons and colleagues selected by Simons himself were unable, independently of one another, to find the same trigger points in patients with muscle pain complaints (myofascial pain). Fred Wolfe, the lead researcher who had been skeptical for some time, later wrote about this [18]:

A group of four myofascial pain experts, selected by Simons and including Simons, blindly examined four patients with MFP. The examiners were allowed to take as much time as they needed; they could examine but not interview the patients. As we had mixed MFP patients with those who had fibromyalgia, it was a blinded experiment. These MFP experts were no ordinary examiners. They were the best. They wrote the book, they did the lectures. But, in the end, they could not find or agree on the trigger points. It was a disaster.

This was in 1992. In 2004, Simons therefore returned to his 1976 prediction [14,19]. He admitted that acceptance of trigger points was being hampered by the lack of a standard for diagnosis and the lack of a generally recognized disease entity.

With the new studies by Chen and Shaw in 2007 and 2008, he immediately picked up his pen to announce this happy fact.

Two studies appearing in Archives, one by Shah and colleagues and another one by Chen and colleagues, present groundbreaking findings that can reduce some of the controversy surrounding myofascial trigger points (MTPs)

-D.G. Simons, Emory University

"Groundbreaking findings". I understand why Simons became enthusiastic. He probably had a kind of "Higgs boson moment" (for the physicists among us) [20]. However, the MRE studies used only a handful of subjects, respectively 7 and 8 [4,5]. As for the waste products found by Shaw, Quintner and colleagues point out in their 2015 study that these are also found with inflammation or altered nerve function [10,21,22].

Studies since then that tried to demonstrate trigger points with imaging techniques also appear to have various shortcomings [23,24,25]. Developments so far have therefore still not led to a standard.

"Investigate other suspects"

Quintner and Cohen, the critics of the muscle knot theory, have an alternative theory of their own [26]. They noticed that so-called trigger points are "coincidentally" often near known peripheral nerve cells.

Noting the remarkable proximity of TrPs to known peripheral nerves, these authors argued that sensitization of the axons within the nerves, possibly by inflammation, may inform the underlying mechanism. Subsequent research has emerged in support of this hypothesis.

They mention it only as an alternative cause of complaints, one that, like other possibilities, should be explored and investigated further. Think of a murder investigation in which the detectives are asked to look beyond the suspect identified by an eyewitness.

Bruised egos

There is no 'I' in 'Team'. But there is one in 'Science'. In the discussion around trigger points, we see that being proven right has become a matter of honor and that egos play a major role. Especially for the "Simons&Travell side", the proponents of the common trigger point theory, it is a matter of saving face.

Earlier I mentioned Higgs, the physicist who, together with colleagues, argued on the basis of calculations that there had to be a particle we had never observed until then. Forty years and about 6 billion euros later, it was discovered that the particle existed. All theories up to that point based on the particle were assumptions.

When it comes to muscle knots, that particle still seems not to have been found. Yet we see all kinds of treatments aimed at it. If you say that muscle knots do not exist, it is almost as if you are calling all those practitioners quacks.

It is therefore not surprising that the critical study by Quintner, Bove and Cohen from 2015 received a response that same year from "trigger point disciples" [27]. In this case, the response came from, among others, the Dutch therapist working in America Jan Dommerholt, who wrote dozens of articles about trigger points and gives seminars on dry needling.

What follows is an extremely fascinating but lengthy discussion with arguments back and forth about the validity of arguments and the strength or weakness of studies.

For me to form a definitive judgment in the two weeks I have been writing this article is therefore impossible. We have researchers arguing among themselves about decades of research, so who am I to decide who is right? I will wait until more research has been done and the referee raises the winner's hand while the other lies flat on the canvas.

If I am the patient before that time, I will still raise an eyebrow when I hear someone talk about treating my muscle knots. And if I do let someone place needles in my muscles, I hope he or she has not read this article.

The thing that speaks most against the common trigger point theory is the fact that different practitioners apparently cannot find the same trigger points in the same patient. If they exist, that is not much use if you do not know how to find them. If there are practitioners who say this is nonsense, then of course we would gladly take on the test.

Why do we read so little about the criticism and so much about the common theory and treatments? Probably because there is more money to be made from it and many people make their living from it.

References

1. Alvarez DJ, Rockwell PG. Trigger points: diagnosis and management. Am Fam
   Physician. 2002 Feb 15;65(4):653-60. Review. PubMed PMID: 11871683.
2. Simons DG, Travell JG, Simons LS. Travell & Simons' Myofascial pain and dysfunction: the trigger point manual. 2d ed. Baltimore: Williams & Wilkins, 1999:94–173.
3. Shah JP, Danoff JV, Desai MJ, Parikh S, Nakamura LY, Phillips TM, Gerber LH.Biochemicals associated with pain and inflammation are elevated in sites near to and remote from active myofascial trigger points. Arch Phys Med Rehabil. 2008 Jan;89(1):16-23. doi: 10.1016/j.apmr.2007.10.018. PubMed PMID: 18164325.
4. Chen Q, Bensamoun S, Basford JR, Thompson JM, An KN (December 2007). "Identification and quantification of myofascial taut bands with magnetic resonance elastography" (PDF). Archives of Physical Medicine and Rehabilitation 88 (12): 1658–61. doi:10.1016/j.apmr.2007.07.020. PMID 18047882.
5. Chen Q, Basford J, An KN. Ability of magnetic resonance elastography to assess taut bands. Clin Biomech 2008;23:623-9.
6. Myburgh, C; Larsen AH; Hartvigsen J. (2008). "A systematic, critical review of manual palpation for identifying myofascial trigger points: evidence and clinical significance". Arch Phys Med Rehabil 89 (6): 1169–76. doi:10.1016/j.apmr.2007.12.033. PMID 18503816. Retrieved 2012-07-23.
7. Simons DG (2008). "New views of myofascial trigger points: etiology and diagnosis". Archives of Physical Medicine and Rehabilitation 89 (1): 157–9. doi:10.1016/j.apmr.2007.11.016. PMID 18164347.
8. Sikdar S, Shah JP, Gebreab T, Yen RH, Gilliams E, Danoff J, Gerber LH. Novel
   applications of ultrasound technology to visualize and characterize myofascial trigger points and surrounding soft tissue. Arch Phys Med Rehabil. 2009 Nov;90(11):1829-38. doi: 10.1016/j.apmr.2009.04.015. PubMed PMID: 19887205; PubMed Central PMCID: PMC2774893.
9. Celik D, Mutlu EK. Clinical implication of latent myofascial trigger point. Curr Pain Headache Rep. 2013 Aug;17(8):353. doi: 10.1007/s11916-013-0353-8.
   Review. PubMed PMID: 23801006.
10. Quintner JL, Bove GM, Cohen ML. A critical evaluation of the trigger point phenomenon. Rheumatology (Oxford). 2015 Mar;54(3):392-9. doi: 10.1093/rheumatology/keu471. Epub 2014 Dec 3. Review. PubMed PMID: 25477053.
11. Travell, J.G. & Simons, D.G. Myofascial pain and dysfunction: The trigger point manual (Williams & Willkins, Baltimore, 1983).
12. Gowers WR. A lecture on lumbago: its lessons and analogues. Br Med J 1904;i:117-21.
13. Stockman. A discussion on fibrositis. Proc R Soc Med 1913;6:36-9.
14. Simons DG. Muscle pain syndromes-Part II. Am J Phys Med 1976;55:15-42.
15. Grimes, William (April 17, 2010). "David Simons, Who Flew High on Eve of Space Age, Dies at 87". The New York Times.
16. "David G. Simons". International Space Hall of Fame. 2005 - 2014. Retrieved January 14, 2014.
17. Wolfe, F. et al. The fibromyalgia and myofascial pain syndromes: a preliminary study of tender points and trigger points in persons with fibromyalgia, myofascial pain syndrome and no disease. J Rheumatol 19, 944-51 (1992).
18. fmperplex.com/2013/02/14/travell-simons-and-cargo-cult-science/
19. Simons DG. Review of enigmatic MTrPs as a common cause of enigmatic musculoskeletal pain and dysfunction. J Electromyogr Kinesiol 2004;14:95-107.
20. Siegfried, T. (20 July 2012). "Higgs Hysteria". Science News. Retrieved 2012-12-09. In terms usually reserved for athletic achievements, news reports described the finding as a monumental milestone in the history of science.
21. Mense S. Algesic agents exciting muscle nociceptors. Exp Brain Res 2009;196:89-100.
    CrossRefMedlineWeb of ScienceGoogle Scholar
22. Chiu IM, von Hehn CA, Woolf CJ. Neurogenic inflammation and the peripheral nervous system in host defense and immunopathology. Nat Neurosci 2012;15:1063-67.
23. Ballyns JJ, Shah JP, Hammond J, et al. Objective sonographic measures for characterizing myofascial trigger points associated with cervical pain. J Ultrasound Med 2011;30:1331-40.
24. Niraj G, Collett BJ, Bone M. Ultrasound-guided trigger point injection: first description of changes visible on ultrasound scanning in the muscle containing the trigger point. Br J Anaesth 2011;107:474-5.
25. Gokhale S. Sonography in identification of abdominal wall lesions presenting as palpable masses. J Ultrasound Med 2006;25:1199-209.
26. Quintner JL, Cohen ML. Referred pain of peripheral nerve origin: an alternative to the “myofascial pain” construct. Clin J Pain 1994;10:243-51.
27. fmperplex.com/2015/03/05/a-critical-evaluation-of-the-trigger-point-phenomenon-continued/

Other sources:

• Travell J, Rinzler SH. The myofascial genesis of pain. Postgrad Med 1952;11:425-34
• Singh, S; Ernst, E (2008). Trick or Treatment: Alternative Medicine on Trial. London: Bantam. ISBN 9780593061299.
• Ahn, Andrew C.; Colbert, Agatha P.; Anderson, Belinda J.; Martinsen, ØRjan G.; Hammerschlag, Richard; Cina, Steve; Wayne, Peter M.; Langevin, Helene M. (2008). "Electrical properties of acupuncture points and meridians: A systematic review" (PDF). Bioelectromagnetics 29 (4): 245–256. doi:10.1002/bem.20403. PMID 18240287.
• de las Peñas, César Fernández; Arendt-Nielsen, Lars; Gerwin, Robert D (2010). Tension-type and cervicogenic headache: pathophysiology, diagnosis, and management. Jones & Bartlett Learning. pp. 251–254. ISBN 9780763752835.
• Mann, F (2000). Reinventing Acupuncture: A New Concept of Ancient Medicine. Elsevier. ISBN 0750648570.
• Williams, WF (2013). Encyclopedia of Pseudoscience: From Alien Abductions to Zone Therapy. Encyclopedia of Pseudoscience (Routledge). pp. 3–4. ISBN 1135955220.
• Tough EA, White AR, Richards S, Campbell J (March–April 2007). "Variability of criteria used to diagnose myofascial trigger point pain syndrome-evidence from a review of the literature". Clin J Pain 23 (3): 278–86. doi:10.1097/AJP.0b013e31802fda7c. PMID 17314589.
• Lucas N, Macaskill P, Irwig L, Moran R, Bogduk N (January 2009). "Reliability of physical examination for diagnosis of myofascial trigger points: a systematic review of the literature". Clin J Pain 25 (1): 80–9. doi:10.1097/AJP.0b013e31817e13b6. PMID 19158550.