Neuromuscular manifestations of work-related myalgia in women specific to extensor carpi radialis brevis.
This study assessed neuromuscular function in the extensor carpi radialis brevis (ECRB) of female workers diagnosed with work-related myalgia (WRM, n = 14, age 45.2 ± 1.9 years) and the ECRB of healthy controls (CON, n = 10, age 34.6 ± 2.5 years). Groups were compared on voluntary and electrically evoked functional responses at rest (Pre), immediately following a 5 min repetitive task (Post-0) performed at 60% maximal voluntary contraction (MVC), and after 5 min of recovery (Post-5). Despite near complete motor unit activation (MUA) (CON 98% ± 1% vs. WRM 99% ± 1%), at Pre, WRM produced 26% less (P < 0.05) MVC force than CON. Following an MVC, twitch force was increased (P < 0.05) by 94% ± 13% and 54% ± 11% in CON and WRM, respectively (CON vs. WRM; P < 0.05). The peak force and the maximal rates of force development and decline of electrically evoked contractions (10-100 Hz) were generally depressed (P < 0.05) at Post-0 and Post-5 relative to Pre. The response pattern to increasing frequencies of stimulation was not different (P > 0.05) between groups and MUA was not impaired (CON 97% ± 1% vs. WRM 97% ± 1%; P > 0.05). In conclusion, the peripheral weakness observed in the ECRB in WRM at rest does not result in abnormal fatigue or recovery responses after performing a task controlled for relative demand (60% MVC).
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.|b Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD), Waterloo, ON N2L 3G1, Canada.
Howard J
HJ
Green
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.|d Disability Assessment Services Inc., Waterloo, ON N2B 1Y4, Canada.
Don
D
Ranney
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Natasha
N
Kyle
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
David
D
Lounsbury
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Ian C
IC
Smith
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Riley
R
Stewart
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Melissa M
MM
Thomas
c Mind Body Medicine, The RSI Clinic, Toronto, ON M4T 1M6, Canada.|e Department of Anaesthesiology and Pain Medicine, University of Washington, Seattle, WA 98195, USA.
Heather
H
Tick
a Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
A Russell
AR
Tupling
D000328:Adult; D002908:Chronic Disease; D004576:Electromyography; D005260:Female; D005542:Forearm; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018908:Muscle Weakness / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D063806:Myalgia / Q000503:physiopathology*; D009784:Occupational Diseases / Q000503:physiopathology*
court extenseur radial du carpe; extensor carpi radialis brevis; fatigue; femmes; myalgia; myalgie; neuromusculaire; neuromuscular; travail; women; work