Restoration of voluntary muscle strength after 3 weeks of cast immobilization is suppressed in women compared with men.
OBJECTIVE
To investigate sex-related differences in the loss and recovery of voluntary muscle strength after immobilization.


METHODS
Longitudinal, repeated measures.


METHODS
Research laboratory.


METHODS
Healthy men (n=5) and healthy women (n=5).


METHODS
Three weeks of forearm immobilization.


METHODS
Voluntary wrist flexion muscle strength was assessed at baseline and weekly during the immobilization protocol and 1 week after cast removal. Central activation was assessed before and after immobilization and after 1 week of recovery to determine what percentage of the muscle could be activated voluntarily.


RESULTS
Men and women lost voluntary strength at a similar rate during immobilization. However, after 1 week of recovery voluntary strength had returned to within 1% of baseline in the men, but remained approximately 30% less than baseline in the women (P=0.03). Both sexes displayed reduced central activation after immobilization (P=0.02), but the decrease was similar in both sexes (P=0.82).


CONCLUSIONS
These findings suggest sex-dependent adaptations to and recovery from limb immobilization, with voluntary strength recovering slower in women. As such, sex-specific rehabilitation protocols may be warranted, with women requiring additional or more intensive rehabilitation programs after periods of disuse. Future work is needed to determine the extent and mechanisms of these differences.
Clark
Brian C
BC
Interdisciplinary Institute for Neuromusculoskeletal Research, Department of Biomedical Sciences, Ohio University, Athens, OH 45701, USA. clarkb2@ohio.edu
Manini
Todd M
TM
Hoffman
Richard L
RL
Russ
David W
DW
D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D005260:Female; D005542:Forearm; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D053580:Muscle Strength; D009133:Muscular Atrophy / Q000209:etiology / Q000534:rehabilitation*; D020127:Recovery of Function; D012046:Rehabilitation / Q000379:methods*; D012149:Restraint, Physical; D012737:Sex Factors; D055815:Young Adult