Does Stress within a Muscle Change in Response to an Acute Noxious Stimulus?

Tucker, Kylie, Hodges, Paul W., Van den Hoorn, Wolbert, Nordez, Antoine and Hug, Francois (2014) Does Stress within a Muscle Change in Response to an Acute Noxious Stimulus?. PLoS One, 9 3: e91899.1-e91899.7. doi:10.1371/journal.pone.0091899

Author Tucker, Kylie
Hodges, Paul W.
Van den Hoorn, Wolbert
Nordez, Antoine
Hug, Francois
Title Does Stress within a Muscle Change in Response to an Acute Noxious Stimulus?
Journal name PLoS One   Check publisher's open access policy
ISSN 1932-6203
Publication date 2014-03-01
Year available 2014
Sub-type Article (original research)
DOI 10.1371/journal.pone.0091899
Open Access Status DOI
Volume 9
Issue 3
Start page e91899.1
End page e91899.7
Total pages 7
Place of publication San Francisco, CA United States
Publisher Public Library of Science
Language eng
Formatted abstract
Altered muscle activation during pain is thought to redistribute stress within muscles and ultimately decrease the load on painful structures. However, change in muscle stress during pain has not been directly tested. The aim of the present study is to determine whether stress within muscle tissue is reduced during local acute experimental pain.

Methods and Results
Ten participants attended 2 experimental sessions that each involved isometric knee extension tasks in 2 series of control trials and 1 series of test trials at ~10%MVC. Shear elastic modulus was measured from vastus lateralis using a shear wave elastographic technique (Supersonic Shear Imaging). Prior to the test contractions, a bolus of hypertonic (Pain) or isotonic saline (No-pain) was injected into vastus lateralis. Pain intensity was 5.2±1.0 during the painful contractions. The intra-session repeatability of the shear elastic modulus determined between control trials was good (ICC: 0.95 and 0.99; SEM: 5.1 and 9.3 kPa for No-pain and Pain, respectively). Muscle shear elastic modulus did not change systematically during Pain or No-pain contractions (all main effects and interaction P>0.14). Examination of data for individual participants showed that stress either increased or decreased. If the absolute change in modulus is considered between the control and the test trials, the change during Pain (16.2±9.5 kPa) was double that observed with No pain (7.9±5.9 kPa; P = 0.046).

This is the first study to directly determine the change in stress within a muscle (change in shear elastic modulus) during pain. We conclude that experimental pain induced by hypertonic saline does not induce a systematic reduction in muscle stress during a single-joint isometric task. Therefore, the changes in muscle activity reported previously during similar tasks are unlikely to systematically reduce load in the painful region. Whether the individual-specific increase and decrease are physiologically relevant or purposeful requires further investigation. 
Keyword Motor Unit Recruitment
Shear elastic modulus
Firing Rate
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID ID401599
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Biomedical Sciences Publications
School of Health and Rehabilitation Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
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