Electromyographic activity of selected trunk and hip muscles during a squat lift: Effect of varying the lumbar posture

J. P. Vakos, A. J. Nitz, A. J. Threlkeld, R. Shapiro, T. Horn

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


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 <, 05) were seen among subjects and in the timing of the muscle activity in ell muscles- Differences (p<. 05) were found In ES EMG activity in quarters one, three, and four and in ST EMG activity in quarts four when comparing the lifting styles. The increased ES EMG activity seen in the lotdotic lift in the first quarter suggests ils greater involvement in lumbar spine support. This supports the clinical observation that lining with the lumbar spine in lordo- sis is advantageous. No significant differences wera found in the hip extensor EMG during the early stages of the lift.

Original languageEnglish
Pages (from-to)687-695
Number of pages9
Issue number6
StatePublished - Mar 1994


  • Abdominal muscles
  • Anatomy
  • Biomechanics
  • Filing
  • Hip
  • Hip muscles
  • Lumbosacral region
  • Posture
  • Trunk muscles thoracolumbar fascia

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology


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