Effects of Neuromuscular Electrical Stimulation and Resistance Training on Knee Extensor/Flexor Muscles

Abstract

Neuromuscular electrical stimulation (NMES) has recently drawn a lot of attention as means for strengthening of voluntary muscle contraction both in sport and rehabilitation. NMES training increases maximal voluntary contraction (MVC) force output through neural adaptations. On the other hand, positive effects of resistance training (RT) on muscle strength are well known. The aim of this study was to investigate effects of a 5-week program of NMES compared to RT program of same duration. Sample of 15 students’ of faculty of sport and physical education (age 22±2) were randomized in two groups: NMES (N=7) and RT (N=8). NMES group performed NMES superimposed over voluntary muscle contraction, RT group performed resistance training with submaximal loads. Subjects were evaluated for knee isokinetic dynamometry on both sides (60º and 180º s). After intervention no significant difference between groups were observed in isokinetic dynamometry (p=0.177). However, applying pair sample t test within each group revealed that peak torque increased in NMES group (p=0.002 for right knee extensors muscles, p=0.003 for left, respectively, at 60º and p=0.004 for left knee extensors muscles, at angular velocity 180º). In RT group (p=0.033 for right knee extensors muscles, p=0.029 for right knee flexor muscles, at angular velocity 60º). Our results indicate that NMES has equal potential if not in some way better than classical RT, having in mind that overload on locomotor apparatus during NMES is minimal and force of muscle contraction is equal on both sides, for enhancement of knee muscles concentric peak torque.