Electromyographic study of the relationship between hamstring and abdominal muscles during a unilateral straight leg raise

T. P. Mayhew, B. J. Norton, S. A. Sahrmann

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12 Scopus citations

Abstract

The purposes of this study were 1) to assess the relative participation of the hip extensor and abdominal musculature during unilateral straight leg raising in the naive subject and 2) to examine quantitatively alterations in the pattern of pelvic stabilization when the subject was instructed to relax the contralateral extremity. Surface electrodes were used to record bilaterally the electromyographic activity of the rectus abdominus, external oblique, and medial hamstring muscles. Each healthy subject performed a unilateral straight leg raise three times in each of two modes, Preferred and Relaxed. The electromyographic values for each muscle were normalized to a maximum isometric contraction and analyzed using a three-factor (2 x 2 x 2) mixed design analysis of variance. Results indicate that 9 of the 11 subjects used the tested medial hamstrings and abdominal muscles during a unilateral straight leg raise performed in the Preferred Mode. When instructed to relax the contralateral extremity for the Relaxed Mode, abdominal muscle activity increased significantly (p < .01). The findings indicate that although most subjects normally stabilize with the contralateral extremity during a unilateral straight leg raise, they can consciously alter the pattern.

Original languageEnglish
Pages (from-to)1769-1775
Number of pages7
JournalPhysical therapy
Volume63
Issue number11
StatePublished - Jan 1 1983

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