Effect of a combination of whole-body vibration and low resistance jump training on neural adaptation.

This study investigated and compared the effects of an eight-week program of whole body vibration combined with counter-movement jumping (WBV + CMJ) or counter-movement jumping (CMJ) alone on players. Twenty-four men's volleyball players of league A or B were randomized to the WBV + CMJ or CMJ groups (n = 12 and 12; mean [SD] age of 21.4 [2.2] and 21.7 [2.2] y; height of 175.6 [4.6] and 177.6 [3.9] cm; and weight, 69.9 [12.8] and 70.5 [10.7] kg, respectively). The pre- and post-training values of the following measurements were compared: H-reflex, first volitional (V)-wave, rate of electromyography rise (RER) in the triceps surae and absolute rate of force development (RFD) in plantarflexion and vertical jump height. After training, the WBV + CMJ group exhibited increases in H reflexes (p = 0.029 and <0.001); V-wave (p < 0.001); RER (p = 0.003 and <0.001); jump height (p < 0.001); and RFD (p = 0.006 and <0.001). The post-training values of V wave (p = 0.006) and RFD at 0-50 (p = 0.009) and 0-200 ms (p = 0.008) in the WBV + CMJ group were greater than those in the CMJ group. This study shows that a combination of WBV and power exercise could impact neural adaptation and leads to greater fast force capacity than power exercise alone in male players.

Comparative and reliability studies of neuromechanical leg muscle performances of volleyball athletes in different divisions.

This study compared neural profiles of the leg muscles of volleyball athletes playing in different divisions of Taiwan's national league to analyse the reliability and correlations between their profiles and biomechanical performances. Twenty-nine athletes including 12 and 17 from the first and second divisions of the league, respectively, were recruited. The outcome measures were compared between the divisions, including soleus H-reflex, first volitional (V) wave, normalised rate of electromyography (EMG) rise (RER) in the triceps surae muscles, and RER ratio for the tibialis anterior and soleus muscles, normalised root mean square (RMS) EMG in the triceps surae muscles, antagonist co-activation of the tibialis anterior muscle, rate of force development (RFD), and maximal plantar flexion torque and jump height. Compared to the results of the second division, the neural profiles of the first division showed greater normalised V waves, normalised RER in the lateral gastrocnemius, and normalised RMS EMG of the soleus and lateral gastrocnemius muscles with less antagonist co-activation of the tibialis anterior. First division volleyball athletes showed greater maximal torque, jump height, absolute RFD at 0-30, 0-100, and 0-200 ms, and less in the normalised RFD at 0-200 ms of plantar flexion when compared to the results of those in the second division. Neural profiles correlated to fast or maximal muscle strength or jump height. There are differences in the descending neural drive and activation strategies in leg muscles during contractions between volleyball athletes competing at different levels. These measures are reliable and correlate to biomechanical performances.