Assessment of whole body vibrations, conventional weights training or their combination: effects of an 8-weeks conditioning programme on jumping and isometric strength tests

Introduction Whole body vibrations (WBV) have been studied as an alternative exercise intervention for enhancing muscle strength and power. Some authors have investigated their influence on the neuromuscular and neuroendocrine system1. Despite the encouraging findings on untrained individuals, it is still not clear whether WBV training may be beneficial for elite athletes. The aim of this work is to compare the effectiveness of similar training programmes, consisting of WBV, traditional resistance exercise with weights or their combination. Methods 18 healthy competitive female athletes (23.84.6 y; 1.660.05 m; 58.87.8 kg) were randomly assigned to 3 treatment groups (V, B and VB). They carried out an 8-weeks periodised conditioning programme, 2 cycles of 3 weeks with 2 training session each, followed by a week of tapering. During training sessions, subjects performed 6 sets of 6 repetitions of dynamic squat: on a vibrating platform (Nemes LX-B/E, SAIR, Italy) (V); with a weight loaded barbell (B); with a weight loaded barbell on a vibrating platform (VB). Vibration frequency was initially set at 25 Hz and was increased of 5 Hz every 2 weeks for both V and VB. Barbell loads were set at 60% and 30% of subject s body mass (BM) for B and VB, respectively, and was increased of about 3% (for VB) and 6% BM (for B) every 2 weeks. Countermovement jump and isometric force tests were carried out before and after the training period. Jumping height and power were estimated by Optojump system (Microgate, Italy). Isometric force was measured by force platforms (Twin Plates, Globus, Italy). They were fixed onto the footplate of a leg press, whose seat was locked so that the subject s knees maintained a 90 deg flexion angle. Proper recovery intervals were respected to avoid fatigue. Following a normality test, non-parametric within groups tests (Wilcoxon) were applied (=0.05). Results Jumping height (mean over 3 trials) and jumping height and power (mean over 15 s of continuous jumping) significantly increased only in group B: they improved from (median (IQR)) 27.3 (5.0) cm, 22.7 (7.6) cm and 18.4 (7.3) W/kg, to 30.5 (7.9) cm, 25.7 (5.3) cm and 22.4 (4.6) W/kg. Isometric tests manifested statistically significant improvements only in group V, for which median T30 and T50 (time to 30 and 50% of maximal isometric force) increased from 64 (17) ms and 92 (16) ms, to 72 (16) ms and 100 (31) ms. Discussion/Conclusion Results suggested that no apparent enhancements in either dynamic or isometric muscular force were induced by WBV either alone or in combination with light resistance exercise with the protocols used in this study. In contrast, conventional resistance training seemed to improve vertical jumping ability. References 1. Cardinale, M. and Wakeling, J. (2005) Br J Sports Med. 39:585-589.