Comparison of muscle activity during prone hip extension in individuals with and without chronic low back pain

Abstract

[Purpose] Purposes of this study were to compare the electromyography amplitudes of the back and hip extensor in individuals with and without chronic low back pain (CLBP) and to identify alteration in the muscle recruitment pattern during prone hip extension associated with CLBP. [Subjects] Twenty persons with CLBP and 20 healthy persons participated. [Methods] Muscle activities were recorded during prone hip extension using a surface electromyography system. The following muscles were evaluated:contralateral latissimus dorsi, bilateral erector spinae, bilateral multifidus, gluteus maximus (GM) on the hip extension side, and hamstrings on the hip extension side. Each participant was instructed to extend his hip joint until 10°and to keep this position. The Mann-Whitney U-test was used to determine differences in muscle activity magnitudes between the groups. [Results] The GM activity was significantly greater in the CLBP group than in the control group. There were no significant between-group differences observed for the other muscles examined. [Discussion] Our findings indicate that the GM activity was greater in the CLBP group than in the control group. We believe this increased activity in the CLBP group was caused by reduced GM muscle strength and by increased in the ventral pelvic rotation.