Document Detail

Hip abductor function and lower extremity landing kinematics: sex differences.
MedLine Citation:
PMID:  17597947     Owner:  NLM     Status:  MEDLINE    
CONTEXT: Rapid deceleration during sporting activities, such as landing from a jump, has been identified as a common mechanism of acute knee injury. Research into the role of potential sex differences in hip abductor function with lower extremity kinematics when landing from a jump is limited.
OBJECTIVE: To evaluate sex differences in hip abductor function in relation to lower extremity landing kinematics.
DESIGN: 2 x 2 mixed-model factorial design using a between-subjects factor (sex) and a repeated factor (test).
SETTING: University laboratory.
PATIENTS OR OTHER PARTICIPANTS: A sample of convenience consisting of 30 healthy adults (15 women, 15 men) with no history of lower extremity surgery and no lower extremity injuries within 6 months of testing.
INTERVENTION(S): Landing kinematics were assessed as subjects performed 3 pre-exercise landing trials that required them to hop from 2 legs and land on a single leg. Isometric peak torque (PT) of the hip abductors was measured, followed by an endurance test during which subjects maintained 50% of their PT to the limits of endurance. After a 15-minute rest period, subjects completed a 30-second bout of isometric hip abduction, from which we calculated the percentage of endurance capacity (%E). Immediately after exercise, subjects completed 3 postexercise landing trials.
MAIN OUTCOME MEASURE(S): PT, %E, and peak joint displacement (PJD) of the hip and knee in all 3 planes of motion.
RESULTS: Women demonstrated lower PT values (5.8 +/- 1.2% normalized to body weight and height) than did their male counterparts (7.2 +/- 1.5% normalized to body weight and height, P = .009). However, no sex differences were seen in %E. Women also demonstrated larger knee valgus PJD (7.26 degrees +/- 6.61 degrees) than did men (3.29 degrees +/- 3.54 degrees, P = .04). Women's PT was moderately correlated with hip flexion, adduction, and knee valgus PJD; however, PT did not significantly correlate with men's landing kinematics. Regardless of sex, hip flexion (P = .002) and hip adduction (P = .001) were significantly increased following the 30-second bout of exercise.
CONCLUSIONS: Women demonstrated lower hip abductor PT and increased knee valgus PJD when landing from a jump, potentially increasing the risk of acute knee injury. Furthermore, correlations between hip abductor strength and landing kinematics were generally larger for women than for men, suggesting that hip abductor strength may play a more important role in neuromuscular control of the knee for women.
Cale A Jacobs; Timothy L Uhl; Carl G Mattacola; Robert Shapiro; William S Rayens
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of athletic training     Volume:  42     ISSN:  1938-162X     ISO Abbreviation:  J Athl Train     Publication Date:    2007 Jan-Mar
Date Detail:
Created Date:  2007-06-28     Completed Date:  2007-08-23     Revised Date:  2013-06-06    
Medline Journal Info:
Nlm Unique ID:  9301647     Medline TA:  J Athl Train     Country:  United States    
Other Details:
Languages:  eng     Pagination:  76-83     Citation Subset:  IM    
University of Kentucky, Lexington, KY 40504, USA.
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MeSH Terms
Analysis of Variance
Athletic Injuries / physiopathology,  prevention & control
Hip Joint / physiology*
Lower Extremity
Muscle Contraction / physiology
Muscle Fatigue
Muscle, Skeletal / physiology*
Range of Motion, Articular / physiology*
Sampling Studies
Sensitivity and Specificity
Sex Factors
Stress, Mechanical

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

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