EMG analysis of vastus medialis obliquus and vastus lateralis during semi-squat : a study with different hip and knee positions

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EMG analysis of vastus medialis obliquus and vastus lateralis during semi-squat : a study with different hip and knee positions

 

Author: Lam, Lam Priscillia
Title: EMG analysis of vastus medialis obliquus and vastus lateralis during semi-squat : a study with different hip and knee positions
Year: 1999
Subject: Patellofemoral joint -- Diseases
Knee -- Muscles -- Physiology
Electromyography
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Rehabilitation Sciences
Pages: vii, 71 leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1477367
URI: http://theses.lib.polyu.edu.hk/handle/200/2517
Abstract: An electromyographic study on the muscle activities of vastus medialis obliquus (VMO) and vastus lateralis (VL) was performed. A total of seventeen subjects suffering from patellofemoral joint pain syndrome (PFJS), without traumatic causes were tested. Each subject performed six semi-squat bilateral knee extension exercises in different combinations of hip and knee positions, namely, hip in 30o medial rotation, neutral, and 45o lateral rotation, with knees at either 20o or 40o flexion. Muscle activities of both vastus medialis obliquus and vastus lateralis were measured during static knee extension at 60% of maximal voluntary effort. The ratio of surface integrated electromyographic (EMG) signals of VMO over VL was calculated for each of the six conditions. Data were analyzed separately with paired t-tests for knee positions and one-way repeated measures ANOVA for hip positions. All subjects completed the tests, but one subject complained of moderate level of pain during the test and that subject could not maintain a constant muscle contraction. Therefore the result of this subject was excluded. Results of sixteen subjects showed that at 20o knee flexion, there was no significant difference among the three hip positions. However, at 40o knee flexion, medial hip rotation was found to have significantly higher VMO/VL ratio than lateral hip rotation (P<0.05). This result demonstrated a preferential activation of VMO over VL in a semi-squatting position with hip medially rotated. Finding of this study provides a new training position for VMO in patients with PFJS.

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