Trigger points are acidic and contain pain-causing metabolites
PainSci summary of Shah 2008?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★★☆?4-star ratings are for bigger/better studies and reviews published in more prestigious journals, with only quibbles. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.
This significant paper demonstrates that the biochemical milieu of trigger points is acidic and contains a lot of pain-causing metabolites: this is among the best evidence supporting 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 own short article: Toxic Muscle Knots.
The validity of these findings have been questioned by Quintner et al. I think their concerns are justified, but it is a legitimate and unfinished scientific controversy.
original abstract†Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
OBJECTIVES: To investigate the biochemical milieu of the upper trapezius muscle in subjects with active, latent, or absent myofascial trigger points (MTPs) and to contrast this with that of the noninvolved gastrocnemius muscle.
DESIGN: We used a microanalytic technique, including needle insertions at standardized locations in subjects identified as active (having neck pain and MTP), latent (no neck pain but with MTP), or normal (no neck pain, no MTP). 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, using immunocapillary electrophoresis and capillary electrochromatography. Pressure algometry was obtained. We compared analyte concentrations among groups with 2-way repeated-measures analysis of variance.
SETTING: A biomedical research facility.
PARTICIPANTS: Nine healthy volunteer subjects.
INTERVENTIONS: Not applicable.
MAIN OUTCOME MEASURES: Preselected analyte concentrations.
RESULTS: Within the trapezius muscle, concentrations for all analytes were higher in active subjects than in latent or normal subjects (P<.002); pH was lower (P<.03). At needle insertion, analyte concentrations in the trapezius for the active group were always higher (pH not different) than concentrations in the gastrocnemius muscle. At all times within the gastrocnemius, the active group had higher concentrations of all analytes than did subjects in the latent and normal groups (P<.05); pH was lower (P<.01).
CONCLUSIONS: We have shown the feasibility of continuous, in vivo recovery of small molecules from soft tissue without harmful effects. 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.
related content
- “An in vivo microanalytical technique for measuring the local biochemical milieu of human skeletal muscle,” an article in Journal of Applied Physiology, 2005.
Specifically regarding Shah 2008:
- “New Views of Myofascial Trigger Points: Etiology and Diagnosis,” an article in Archives of Physical Medicine & Rehabilitation, 2008.
- PS Toxic Muscle Knots — Research suggests myofascial trigger points may be quagmires of irritating molecules
These twelve articles on PainScience.com cite Shah 2008 as a source:
- PS Trigger Points & Myofascial Pain Syndrome — A guide to the unfinished science of muscle pain, with reviews of every theory and self-treatment and therapy option
- PS Save Yourself from Low Back Pain! — Low back pain myths debunked and all your treatment options reviewed
- PS Save Yourself from Plantar Fasciitis! — Plantar fasciitis explained in great detail, including every possible treatment option, and all supported by recent scientific research
- PS Save Yourself from Shin Splints! — Causes and treatment options for shin splints explained and discussed in great detail, especially shin pain caused by myofascial trigger points, compartment syndrome, medial tibial stress syndrome, and stress fracture
- PS Save Yourself from Neck Pain! — A complete guide to chronic neck pain and the disturbing sensation of a “crick”
- PS Basic Self-Massage Tips for Myofascial Trigger Points — Learn how to massage your own trigger points (muscle knots)
- PS Micro Muscles and the Dance of the Sarcomeres — A mental picture of muscle knot physiology helps to explain four familiar features of muscle pain
- PS Heat for Pain — When and how to apply heat for therapy … and when not to!
- PS Into the Fire — Trigger point pain as a major injury complication, and how I finally “miraculously” healed from a serious and stubborn shoulder injury by untying the muscle knots
- PS Why Drink Water After Massage? — Massage therapy does not flush toxins into the bloodstream, and water wouldn’t help if it did
- PS The Trigger Point Identity Crisis — The biological evidence that a trigger point is a lesion in muscle tissue
