Purpose: The purpose of this study was to compare the effects of an 8-week whole-body vibration training program in various frequency and amplitude settings under the same acceleration on the strength and power of the knee extensors.
Methods: Sixty-four young participants were randomly assigned to 1 of 4 groups with the same acceleration (4 g): high frequency and low amplitude (n = 16, 32 Hz, 1 mm) group, medium frequency and medium amplitude (n = 16, 18 Hz, 3 mm) group, low frequency and high amplitude (n = 16, 3 Hz, 114 mm) group, and control (n = 16, no vibration) group. All participants underwent 8 weeks of training with body mass dynamic squats, 3 sessions a week.
Results: The results showed that the high frequency and low amplitude group increased significantly in isometric contraction strength and 120°/s isokinetic concentric contraction strength; the medium frequency and medium amplitude group increased significantly in 60°/s and 120°/s isokinetic strength of both concentric and eccentric contraction; and the low frequency and high amplitude group increased significantly in 60°/s and 120°/s isokinetic eccentric contraction strength.
Conclusion: All frequency and amplitude settings in the 8-week whole-body vibration training increased muscle strength, but different settings resulted in various neuromuscular adaptations despite the same intensity.
Keywords: Isokinetic contraction strength; Muscle contraction speed; Neuromuscular adaptation; Vibration acceleration; Vibration amplitude; Vibration frequency.