Document Detail

Hamstring strength and morphology progression after return to sport from injury.
MedLine Citation:
PMID:  23059864     Owner:  NLM     Status:  MEDLINE    
PURPOSE: Hamstring strain reinjury rates can reach 30% within the initial 2 wk after return to sport (RTS). Incomplete recovery of strength may be a contributing factor. However, relative strength of the injured and unaffected limbs at RTS is currently unknown.The purpose was to characterize hamstring strength and morphology at the time of RTS and 6 months later.
METHODS: Twenty-five athletes who experienced an acute hamstring strain injury participated after completion of a controlled rehabilitation program. Bilateral isokinetic strength testing and magnetic resonance imaging (MRI) were performed at RTS and 6 months later. Strength (knee flexion peak torque, work, and angle of peak torque) and MRI (muscle and tendon volumes) measures were compared between limbs and over time using repeated-measures ANOVA.
RESULTS: The injured limb showed a peak torque deficit of 9.6% compared to the uninjured limb at RTS (60°·s, P < 0.001) but not 6 months after. The knee flexion angle of peak torque decreased over time for both limbs (60°·s, P < 0.001). MRI revealed that 20.4% of the muscle cross-sectional area showed signs of edema at RTS with full resolution by the 6-month follow-up. Tendon volume of the injured limb tended to increase over time (P = 0.108), whereas muscle volume decreased between 4% and 5% in both limbs (P < 0.001).
CONCLUSIONS: Residual edema and deficits in isokinetic knee flexion strength were present at RTS but resolved during the subsequent 6 months. This occurred despite MRI evidence of scar tissue formation (increased tendon volume) and muscle atrophy, suggesting that neuromuscular factors may contribute to the return of strength.
Jennifer L Sanfilippo; Amy Silder; Marc A Sherry; Michael J Tuite; Bryan C Heiderscheit
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  45     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-02-22     Completed Date:  2013-09-26     Revised Date:  2014-03-09    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  448-54     Citation Subset:  IM; S    
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MeSH Terms
Analysis of Variance
Edema / etiology
Knee Joint / physiology
Magnetic Resonance Imaging
Muscle Strength*
Muscle Strength Dynamometer
Muscle, Skeletal / injuries*,  pathology,  physiopathology*
Range of Motion, Articular
Recovery of Function*
Sprains and Strains / pathology,  physiopathology*,  rehabilitation
Tendons / pathology
Time Factors
Young Adult
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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