EMG Activity of Selected Trunk and Hip Muscles During a Squat Lift: Effect of Varying the Lumbar Posture.

摘要

The electromyographic (EMG) activity of selected hip and trunk muscles was recorded during a squat lift and the effects of two different lumbar spine postures were examined. Seven muscles were analyzed: rectus abdominis (RA), abdominal oblique (AO), erector spinae (ES), latissimus dorsi (LD), gluteus maximus (GM), biceps femoris (BF), and semitendinosus (ST). The muscles were chosen because of their attachment to the thoracolumbar fascia and their potential to act on the movement of the trunk pelvis and hips. Seventeen healthy male subjects participated in this study. Each subject performed three squat lifts with the lumbar spine in both a lordotic posture and a kyphotic posture. The lift was divided into four equal time phases. EMG activity of each muscle was quantified for each quarter of the lift and normalized also the peak amplitude of a maximal isometric contraction and to the peak amplitude recorded during the activity. A two-way analysis of variance for repeated measures was used to analyze the effects of posture on the amount and timing of EMG activity during the lift. Theses. (js)