Document Detail


Knee joint kinetics in relation to commonly prescribed squat loads and depths.
MedLine Citation:
PMID:  23085977     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Controversy exists regarding the safety and performance benefits of performing the squat exercise to depths beyond 90° of knee flexion. Our aim was to compare the net peak external knee flexion moments (pEKFM) experienced over typical ranges of squat loads and depths. Sixteen recreationally trained men (n = 16; age, 22.7 ± 1.1 years; body mass, 85.4 ± 2.1 kg; height, 177.6 ± 0.96 cm; mean ± SEM) with no previous lower-limb surgeries or other orthopedic issues and at least 1 year of consistent resistance training experience while using the squat exercise performed single-repetition squat trials in a random order at squat depths of above parallel, parallel, and below parallel. Less than 1 week before testing, 1RM values were found for each squat depth. Subsequent testing required the subjects to perform squats at the 3 depths with 3 different loads: unloaded, 50% 1RM, and 85% 1RM (9 total trials). Force platform and kinematic data were collected to calculate pEKFM. To assess the differences among loads and depths, a 2-factor (load and depth) repeated measures analysis of variance with significance set at the p < 0.05 level was used. Squat 1RM significantly decreased 13.6% from the above-parallel to the parallel squat and another 3.6% from the parallel to the below-parallel squat (p < 0.05). Net peak external knee flexion moments significantly increased as both squat depth and load were increased (p ≤ 0.02). Slopes of pEKFM were greater from unloaded to 50% 1RM than when progressing from 50% to 85% 1RM (p < 0.001). The results suggest that typical decreases in squat loads used with increasing depths are not enough to offset increases in pEKFM.
Authors:
Joshua A Cotter; Ajit M Chaudhari; Steve T Jamison; Steven T Devor
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of strength and conditioning research / National Strength & Conditioning Association     Volume:  27     ISSN:  1533-4287     ISO Abbreviation:  J Strength Cond Res     Publication Date:  2013 Jul 
Date Detail:
Created Date:  2013-06-24     Completed Date:  2014-03-26     Revised Date:  2014-06-26    
Medline Journal Info:
Nlm Unique ID:  9415084     Medline TA:  J Strength Cond Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1765-74     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Humans
Kinetics
Knee Joint / physiology*
Male
Muscle Strength / physiology*
Muscle, Skeletal / physiology*
Range of Motion, Articular / physiology*
Resistance Training
Young Adult
Grant Support
ID/Acronym/Agency:
T32 AR047752/AR/NIAMS NIH HHS
Comments/Corrections

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


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