Abstract
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 abdominals (RAl, abdominel obliques (AOL, erector spines (ES), assumes dorsal ILDI gluteus maximums GM), biceps femora’s (BF), and semitandinosus (ST). The muscles were chosen for their attachments to the thoracolumbar fascia and their potential to act on the trunk, pelvis, and hipe. Seventeen healthy male subjects participated in the study. Each subject did three squat lifts with a 157-N crate, with the spire in both a lordotic and kyphotic posture, The lift was divided Into four equal periods, EM G activity of each muscle was quantified for each period and normality to the peak amplitude of в maximal voluntary isometric contraction [MVIC] A two- way analysis of variance [ANOVA] for repeated measures was used to analyze the effects of posture on the amplitude and liming of EM G activity during the lift. Two patterns of EMG Activity were seenr a trunk muscie pattern (RA, AO, ES, and LD]. and a hlp extensor pattern (GM, BF, ET), h the trunk muscle pattern (TP), EMG activity was greatest in the first quarter and decreased as the lift progressed, in the hip ebensor pattern [HP], EMG activity was least in the first quarter, increased in the second and third quarters, and decreased in the final phase of the lift, Differences (P