Comparison of trunk muscle activity according to hip abduction angle during plank exercise

Abstract

Objective: The purpose of this study was to investigate the conditions for the application of various plank exercises to people who require trunk stabilization by comparing trunk muscle activity according to the degree of hip abduction in the plank exercise. Design: Cross-sectional study. Methods: Twenty healthy participants voluntarily participated in this study and the plank exercise was performed under 5 con- ditions (two-legged support plank [TSP] with hip abduction, TSP with hip abduction of 15 degrees, TSP with hip abduction of 30, one-legged support plank [OSP] with hip abduction of 15 degrees, OSP with hip abduction of 30 degrees). In order to measure the trunk muscle activity according to the 5 conditions, surface electromyography was used. The electrical activities of the rectus ab- dominis (RA), external oblique (EO), and internal oblique (IO) muscles were measured during the 5 plank exercises. Subjects practiced each of the 5 conditions three times in random order and the average values were obtained. Results: In the OSP condition with 15/30 degrees of hip abduction, activities of the RA, EO, and IO were significantly greater than during the TSP (p<0.05). In the OSP with 30 degrees of hip abduction condition, activities of the left EO, IO were sig- nificantly greater than other plank exercise conditions (p<0.05). Conclusions: The plank exercise with hip abduction of 30 degrees and the OSP exercise can be suggested as an effective method to enhance the activity of the trunk oblique muscles. Key