The influence of variable range of motion training on hormonal responses and muscle strength

Document Type: Original Article

Author

Department of Exercise physiology, Marvdasht branch, Islamic Azad University, Marvdasht, Iran

Abstract

Introduction: Traditional resistance training increases strength and power; however, exercises that use the entire range of motion (ROM) may not provide the optimal stimulus for enhancing sports performance. The purpose of this investigation was to compare partial ROM vs. full ROM lower-body resistance training on hormonal responses and muscle strength in young women.
Material & Methods: Fourteen young women (age 26.9 ± 5.1 years, height 166.7 ± 5.1 cm, and body mass 62.5 ± 11.8 kg) voluntary to participate in this study. Volunteers were randomly assigned to 2 groups: (a) full ROM (FROM; n = 7) or (b) partial ROM (PROM; n = 7). The subjects in FROM group were introduced to perform hamstring with machine, squat, dead lift and leg press with 60 to 80 percent of one repetition maximum (1RM), 3 days a week for 8 weeks. The subjects in PROM group were introduced to perform that same training with first half ROM and second half ROM with 50 to 80 percent of 1RM, 3 days a week for 8 weeks. Maximal strength was measured by 1RM before and after the intervention and growth hormone (GH), testosterone (Ts), cortisol (Cor) and testosterone to cortisol ratio (Ts/Cor ratio) were measured at baseline and immediately and 30 min after the last season of training.
Results: The results indicated that muscle strength in each station were increased significantly after both of training methods (P<0.05) and no significant differences were observed between FROM and PROM methods. Repeated-measure analyses of variance revealed that GH and Ts levels had not significant changes after the FROM or PROM resistance training; however, Ts/Cor ratio was increased and Cor levels were decreased after both of training methods (P<0.05). For hormonal responses, no significant differences were observed between FROM or PROM resistance training.
Conclusions: The results suggest that muscle strength and hormonal responses can be improved with both FROM and PROM resistance training and there is no significant difference between these methods.

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