The short-term effects of low-load isometric resistance training by the addition of neuromuscular electrical stimulation on the rate of force development in hip abductor muscles

INTRODUCTION: The rate of force development (RFD) is increased by high-load isometric resistance training (RT), whereas not by low-load isometric RT. However, it is unknown whether low-load isometric RT with neuromuscular electrical stimulation (NMES) can increase the RFD. PURPOSE: The aim of this study was to clarify the short-term effects of low-load isometric RT with NMES on the RFD. METHOD: Twenty-four healthy subjects randomly received both low-load RT of the hip abductor muscles with NMES and sham NMES condition. The RFD of the homonymous muscles was assessed at pre-and post-intervention. Time intervals of the RFD were set to 0-50ms (50RFD), 0-100ms (100RFD), 0-200ms (200RFD), and 0-300ms (300RFD). Two-way repeated measures analysis of variance was used to analyze the effects of time and intervention. RESULT: Low-load RT with NMES significantly increased 50 and 100RFD compared to sham NMES condition. On the other hand, 200 and 300RFD were not changed by either condition. CONCLUSIONS: The significantly increased RFD might be related to the factors affecting each RFD interval. This finding might have an important clinical implication for developing a mechanism-based effective training.