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Increased trapezius pain sensitivity is not associated with increased tissue hardness


Tags: muscle pain, trigger points doubts, etiology, classics, biology, neck, muscle, pain problems, pro, head/neck, spine

Three articles on PainSci cite Andersen 2010: (1) The Complete Guide to Trigger Points & Myofascial Pain(2) You’re Really Tight(3) Trigger Point Doubts

PainSci summary of Andersen 2010: ?This page is one of thousands in the 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.

Are muscles “tight” or hard where they hurt? In this experiment, the hardness of the trapezius muscle was tested and compared with sensitive points, before and after intense exercise.

In a dozen healthy patients, the two “typical locations for tender points” were not just soft, but the softest spots in the muscle — the opposite of the what most people (professionals included) would expect. In a dozen healthy patients, the opposite of what most people would expect, and the opposite of what we “know” from trigger point lore. In general, exercise “did not change muscle sensitivity or muscle hardness” and “a heterogeneous distribution of pressure pain sensitivity and muscle hardness was found.” Translation: the conventional wisdom that you’ll find the most pain at “tight” spots in muscles is probably a misleading oversimplification, at best.

It’s not a large experiment, but it didn’t particularly need to be to make this point. Even a small test should have clearly showed that the sorest spots are the hardest — if they really are.

~ Paul Ingraham

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.

Fatiguing exercise can affect muscle pain sensitivity and muscle hardness, as seen with work-related neck and shoulder pain. Objective methods to assess muscle pain sensitivity are important because the reliability of manual assessment is generally poor.

The aim of this study was (1) to compare coexistence of tender points identified by manual palpation and pressure algometry or hardness assessments and (2) to examine the influence of exercise on muscle pain sensitivity and hardness. Fourteen sites in the upper trapezius muscle were selected for assessments in 12 healthy subjects.

Pressure pain thresholds and muscle hardness were examined by computer-controlled pressure algometry at baseline, immediately after static or dynamic exercise, and 20 minutes after static or dynamic exercise. Before recording of pressure pain thresholds, the trapezius muscle was examined for tender points by manual palpation.

Two sites with low pressure pain thresholds were typical locations for tender points, and these were the least hard sites. However, manually detected tender points were often (29%) not colocalized with most sensitive sites according to the pressure algometry. A heterogeneous distribution of pressure pain sensitivity and muscle hardness was found in the upper trapezius. The short duration of exercise until exhaustion did not change muscle sensitivity or muscle hardness in asymptomatic muscles.

PERSPECTIVE: This study confirms clinical findings with heterogeniosity in pain sensitivity and hardness across the upper trapezius muscle. Developments of new techniques that objectively identify tender points are important, but thus far, manual palpation is best clinical practice.

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