Electromyography activity of vastus lateralis muscle during whole-body vibrations of different frequencies.

The aim of this study was to analyze electromyography (EMG) responses of vastus lateralis muscle to different whole-body vibration frequencies. For this purpose, 16 professional women volleyball players (age, 23.9 +/- 3.6 years; height, 182.5 +/- 11.1 cm; weight, 78.4 +/- 5.6 kg) voluntarily participated in the study. Vibration treatment was administered while standing on a vibrating platform with knees bent at 100 degrees (Nemes Bosco-system, Rome, Italy). EMG root mean square (rms) and was recorded for 60 seconds while standing on the vibrating plate in the following conditions: no vibrations and 30-, 40-, and 50-Hz vibration frequencies in random order. The position was kept for 60 seconds in each treatment condition. EMGrms was collected from the vastus lateralis muscle of the dominant leg. Statistical analysis showed that, in all vibration conditions, average EMGrms activity of vastus lateralis was higher than in the no-vibration condition. The highest EMGrms was found at 30 Hz, suggesting this frequency as the one eliciting the highest reflex response in vastus lateralis muscle during whole-body vibrations in half-squat position. An extension of these studies to a larger population appears worthwhile to further elucidate the responsiveness of the neuromuscular system to whole-body vibrations administered through vibrating platforms and to be able to develop individual treatment protocols.