Whole-body vibration combined with extra-load training for enhancing the strength and speed of track and field athletes

The purpose of this study was to investigate whether whole-body vibration (WBV) combined with extra-load training can enhance the strength and speed of trained athletes compared with isolated WBV training or loaded training (LT) only. Twentyone elite male track and field athletes were randomly assigned to a loaded vibration (LV) training group (n = 7), an unloaded vibration (ULV) training group (n = 7), and a LT group (n = 7). During 4 weeks of training, the LV group received the vibration stimulus (30 Hz and 4 mm) accompanied by a load comprising 75% of the maximum voluntary contraction (MVC), the ULV group received the same vibration stimulus without any load, and the LT group received only a load of 75% MVC without any vibration stimulus. The knee extensor isometric strength, and the concentric and eccentric strength were measured using an isokinetic dynamometer at 300°·s^-1at a 30-m sprint speed before and after the training period. A 2-way mixed analysis of variance (time × group) was used to analyze the differences. Significant time × group interactions were observed for all the dependent variables (p ≤ 0.05). Regarding the post hoc analysis results, the LV group exhibited significant improvements for all the dependent variables after training (p ≤ 0.05), whereas the ULV group exhibited significantly reduced sprint speeds (p ≤ 0.05). The LV group demonstrated significantly superior eccentric strength compared with the ULV and LT groups after training (p ≤ 0.05), and the LV group also produced significantly superior sprint speeds compared with the ULV group after training (p ≤ 0.05). Vibration combined with extra-load training for 4 weeks significantly increased the muscle strength and speed of the elite male track and field athletes.