Trigger points are acidic and contain pain-causing metabolites
Fourteen articles on PainSci cite Shah 2008: 1. The Complete Guide to Trigger Points & Myofascial Pain 2. The Complete Guide to Low Back Pain 3. Complete Guide to Plantar Fasciitis 4. The Complete Guide to Chronic Tension Headaches 5. The Complete Guide to Neck Pain & Cricks 6. Basic Self-Massage Tips for Myofascial Trigger Points 7. Micro Muscles and the Dance of the Sarcomeres 8. Heat for Pain and Rehab 9. The Pressure Question in Massage Therapy 10. Why Drink Water After Massage? 11. Complete Guide to Frozen Shoulder 12. The Trigger Point Identity Crisis 13. Does Massage Increase Circulation?
PainSci commentary on 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 wherever possible.
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 better 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 they aren’t deal-breakers either.
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,” Jay P Shah, Terry M Phillips, Jerome V Danoff, and Lynn H Gerber, Journal of Applied Physiology, 2005.
Specifically regarding Shah 2008:
- “New Views of Myofascial Trigger Points: Etiology and Diagnosis,” David G Simons, Archives of Physical Medicine & Rehabilitation, 2008.
- Toxic Muscle Knots — Research suggests myofascial trigger points may be quagmires of irritating molecules
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- No long-term effects after a three-week open-label placebo treatment for chronic low back pain: a three-year follow-up of a randomized controlled trial. Kleine-Borgmann 2022 Pain.
- Exercise and education versus saline injections for knee osteoarthritis: a randomised controlled equivalence trial. Bandak 2022 Ann Rheum Dis.
- Association of Lumbar MRI Findings with Current and Future Back Pain in a Population-based Cohort Study. Kasch 2022 Spine (Phila Pa 1976).
- A double-blinded randomised controlled study of the value of sequential intravenous and oral magnesium therapy in patients with chronic low back pain with a neuropathic component. Yousef 2013 Anaesthesia.
- Is Neck Posture Subgroup in Late Adolescence a Risk Factor for Persistent Neck Pain in Young Adults? A Prospective Study. Richards 2021 Phys Ther.