Comparison of gluteus maximus, hamstring, and multifidus muscle activation during prone hip extension with reciprocal inhibition at different knee flexion angles: An experimental study.

Abstract

BackgroundHip extension exercises with knee flexion are used for individuals with weak hip extensors or hamstring (HAM)-dominant patterns. The relative contribution of the gluteus maximus (GM), semitendinosus (ST), and biceps femoris (BF) may be affected by the degree of knee flexion.ObjectiveThis study compared GM, ST, BF, and multifidus (MF) activation across three knee flexion angles during prone hip extension with reciprocal inhibition (PHERI) and examined GM/ST and GM/BF ratios to identify the angle most effective for selective GM activation.MethodsTwenty healthy males performed PHERI via a non-elastic band at 60°, 90°, and 120° knee flexion. Electromyography recorded MF, GM, ST, and BF activation normalized to maximum voluntary isometric contraction. GM/ST and GM/BF ratios were calculated, and a repeated-measures ANOVA with Bonferroni adjustment analyzed differences among conditions.ResultsGM activation was significantly higher at 90° than at 60° and 120° (p_adj < 0.017). BF activation was significantly lower at 90° than at 120° (p_adj < 0.017). GM/ST and GM/BF ratios were highest at 90° (p < 0.001). Overall differences were significant for all variables (p < 0.05); however, post-hoc analysis revealed no significant pairwise differences for right_MF, left_MF, or ST (p_adj > 0.017). Additionally, no significant pairwise differences were found for GM between 60° and 120°, nor for BF between 60° and 90° and between 60° and 120° (p_adj > 0.017).ConclusionPHERI at 90° knee flexion promotes selective GM activation while reducing HAM contribution, making it suitable for individuals with weak hip extensors or HAM-dominant patterns.