ELECTROMYOGRAPHIC ANALYSIS OF THE SQUAT PERFORMED IN SELF-SELECTED LOWER-EXTREMITY NEUTRAL ROTATION AND 30-DEGREES OF LOWER-EXTREMITY TURN-OUT FROM THE SELF-SELECTED NEUTRAL POSITION
Jc. Ninos et al., ELECTROMYOGRAPHIC ANALYSIS OF THE SQUAT PERFORMED IN SELF-SELECTED LOWER-EXTREMITY NEUTRAL ROTATION AND 30-DEGREES OF LOWER-EXTREMITY TURN-OUT FROM THE SELF-SELECTED NEUTRAL POSITION, The Journal of orthopaedic and sports physical therapy, 25(5), 1997, pp. 307-315
Little research is available on the muscle activity patterns of the lo
wer extremity muscles during dynamic closed chain squatting activities
. The purpose of this study was to examine the effect of lower extremi
ty position during an Olympic squat on the muscle activity patterns of
the vastus medialis, vastus lateralis, semimembranosus/semitendinosus
, and biceps femoris. Twenty-five healthy, untrained subjects, 18-35 y
ears old, were randomly assigned initial squatting positions of either
self-selected neutral or 30 degrees of lower extremity turn-out from
the self-selected neutral position. Surface electromyography and motio
n analysis data were collected simultaneously in 10 degrees intervals
and analyzed from 10-60 degrees of knee flexion in both the ascending
and descending phases of the squat. A four-way analysis of variance in
dicated that the main effects of lower extremity position and the inte
raction of extremity position and knee joint angles were not found to
cause significant changes in muscle activity patterns. Significant cha
nges in muscle activity did occur with changes in knee flexion angles
in the vastus medialis and vastus lateralis but not in the semimembran
osus/semitendinosus or biceps femoris.