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Purpose : Previous studies indicate that muscle strength is increased after whole body vibration (WBV) exercise. But, how muscles behave during WBV exercise in various exercise positions and at different vibration frequencies is unknown This study aimed to analyze electromyography (EMG) responses of skeletal muscles to different vibration frequencies during Whole Body Vibration (WBV) training in various exercise positions. Methods : Twelve healthy adults (6 males and 6 females, age 24.8 ± 2.4 years) participated in this study. Subjects stood on the vibrating POWER PLATE® platform and performed static 1) squat and 2) single leg squat exercise with two joint angle positions for 10 seconds. The three vibration conditions, Non-Vibration, 30Hz, and 50 Hz were compared in random order. Muscle activities of Vastus Medialis, Vastus Lateralis, Rectus Femoris, Biceps Femoris, Semitendinosus and Gluteus Maximus were recorded using surface EMG. Results : In vibration conditions almost all EMG root mean squares of muscles were significantly higher than in Non-Vibration conditions. Discussion : Increasing muscle activity may result from increased neuromuscular activation during WBV. By applying a vibration stimulus Ia-afferents, a reflex contraction referred to as the Tonic Vibration Reflex (TVR) was induced. Increased muscle activation during WBV may be generated with a level of muscle contractions, and neuromuscular responses during WBV may be modulated by the intensity of muscle co-activation and vibration frequencies. Conclusion : In WBV conditions muscle activity was significantly higher than in Non-Vibration conditions. [ABSTRACT FROM AUTHOR]