Effect of Contralateral Hip Position on External and Internal Oblique Muscle Activities during Quadruped Unilateral Leg Lift Exercises

Background Lumbar stabilization exercises are effective for low back pain (LBP) and can be performed in the quadruped position to promote neutral spinal alignment and postural control under low load conditions. Lower limb exercises, such as unilateral leg lifting in the quadruped position, are recommended to improve trunk muscle activation and stability. Various methods can be employed to adjust the difficulty of unilateral leg lifting exercises in this position; however, whether modifications in contralateral hip positioning in the frontal plane can effectively modulate the difficulty remains unclear. Purpose This study aimed to investigate whether changes in contralateral hip abduction or adduction during unilateral leg lifting exercises in the quadruped position influence the electromyographic activity of the internal oblique (IO) and external oblique (EO) muscles and evaluate the potential application of these positional changes for modulating the difficulty of spinal stabilization exercises. Study design Cross-sectional study Methods This study included 25 healthy male participants in their 20s. During unilateral dominant leg lifting exercises in the quadruped position, the contralateral leg was positioned under three different conditions: (1) with 15° of hip abduction (HAB), (2) hip neutral (HN) position, and (3) 10° of hip adduction (HAD). To manage lumbar rotation during unilateral leg lifting exercises, a smartphone-based measurement tool was applied, and surface electromyography was employed to assess the activities of bilateral EO and IO muscles. Repeated measures one-way analysis of variance was conducted to determine the EO and IO muscle activities across three different conditions. Results The difference among the three conditions for EO and IO muscle activities was significant (p<0.05). When lifting the unilateral dominant leg in the quadruped position with HAB, both EO and IO muscle activities increased more significantly than those with HN and HAD (p<0.05). When lifting the unilateral dominant leg in the quadruped position with HAD, EO and IO muscle activities decreased more significantly than those with HN and HAB (p<0.05). Conclusions Modifying the contralateral hip position in the frontal plane may help in controlling the difficulty of exercises and could be utilized in lumbar stabilization training for patients with LBP.