Different fatigue-resistant leg muscles and EMG response during whole-body vibration

Abstract

The purpose of this study was to determine the effects of static whole-body vibration (WBV) on the Electromyograhic (EMG) responses of leg muscles, which are fatigue-resistant in different manner. The study population was divided into two groups according to the values obtained by the Fatigue Index [ Group I: Less Fatigue Resistant (LFR), n= 11; Group II: More Fatigue Resistant (MFR), n= 11]. The repeated electromyographic (EMG) activities of four leg muscles were analyzed the following determinants: (1) frequency (30 Hz, 35 Hz and 40 Hz); (2) stance position (static squat position); (3) amplitude (2 mm and 4 mm) and (4) knee flexion angle (120 degrees), (5) vertical vibration platform. Vibration data were analyzed using Minitab 16 (Minitab Ltd, State College, PA, USA). The significance level was set at p <.05. The study results showed that static WBV stimuli given at different frequencies and amplitudes resulted in a significant increase (p <.05) in compared, the LFR group showed significantly (1) higher rates of quadriceps femoris and hamstring muscle fatigue (p <.05), (2) higher levels of knee extensor and flexor torque (p <.05) and (3) higher percentage increases in EMG activation at higher frequencies (max at 40 Hz) and amplitudes (4 mm) (p <.05). The present study can be used for the optimal prescription of vibration exercise and can serve to guide the development of training programs.