Active straight-leg raise (ASLR) is a physical evaluation procedure to test lumbar spine stability. Several previous studies have reported various methods to control the activation of abdominal muscles during ASLR. We investigated the effects of three different hip positions in frontal plane on abdominal muscles to increase or decrease the difficulty level of lumbar spine stability exercise during ASLR in pain free subjects. Eleven young and healthy subjects voluntarily participated in this study (6 men, 5 women; mean age=24.0±1.2 years, height=160.0±7.3 ㎝, weight=55.0±10.6 ㎏, body mass index=21.5±2.3 ㎏/㎡). The subjects had three trials on each ASLR with hip 10° adduction, neutral hip, and hip 30° abduction. Separate repeated-measures analysis of variance (ANOVA) and the post hoc Bonferroni tests (with α =.05/3=.017) were performed for each muscle among the three different hip positions in frontal plane (ASLR with hip 10° adduction, neutral hip, and hip 30° abduction). The ipsilateral external oblique (EO), contralateral EO, ipsilateral internal oblique/transverse abdominis (IO/TrA), and contralateral IO/TrA were significantly greater in ASLR with hip 30° abduction compared with ASLR with hip 10° adduction. Also, the ipsilateral EO, contralateral EO, and ipsilateral IO/TrA were significantly greater in ASLR with hip 30° abduction compared with ASLR with neutral hip. These results suggest that ASLR with hip 30° abduction and neutral would be useful method to strengthen the EO and IO/TrA. And, ASLR with hip 10° adduction would be effective in early stages of lumbar stabilization program due to low activation of EO and IO/TrA during maintaining of ASLR position with low load.

• Tae-lim Yoon(Applied Kinesiology and Ergonomic Technology Laboratory, Dept. of Physical Therapy, The Graduate School, Yonsei University,)
• Ki-song Kim(Research Institute for Basic Sciences, Dept. of Physical Therapy, College of Natural Science, Hoseo University) Corresponding author