Although exercise combined with WBV is becoming increasingly popular among trained adults, the additional effects of WBV on muscle fitness and performance is still controversially discussed in literature. One reason might be the diversity of WBV training settings. Therefore, this study aimed to (1) identify a favourable WBV training setting and to (2) validate this setting in a four-week intervention with respect to performance related parameters. Methods: (1) In 18 subjects the electromyographic (EMG) activity of six leg muscles was recorded during WBV in order to identify those WBV training conditions that cause highest neuromuscular responses and therefore high activation intensities. The vibration parameters have been varied as follows: a) vibration type (rotational (RV) and vertical vibration (VV)), b) frequency (5-10-15-20-25-30Hz), c) amplitude (2 vs. 4mm) and d) stance condition (forefoot vs. normal stance). The statistical analysis consisted of an ANOVA. (2) In a repeated-measures matched-subject design, 38 participants were assigned in a WBV group (VIB) and training group (CON). Training duration, number of sets, rest periods and task-specific instructions were matched between the groups. The WBV training setting was based on the results of (1). The parameters balance control, jump height and strength endurance were assessed before and after the training period. The statistical analysis consisted of an ANOVA. Results: (1) The combination of high vibration frequencies (30Hz, p<0.05), high amplitudes (4mm, p<0.05) and forefoot stance (p<0.05) on a RV platform (p<0.05) is associated with the highest EMG activity during WBV. (2) Significant interaction effect of group x time could be observed for balance and strength endurance. Hence, WBV causes an additional effect on balance control (CON +6%, p=0.33 and VIB +13%, p<0.05) and strength endurance (CON +11%, p=0.49 and VIB +36%, p<0.05). The effect on jump performance remained insignificant (CON ±0%, 0.25 and VIB +3%, p=0.82). Discussion: There are two main outcomes: (1) an appropriate adjustment of specific WBV parameters provides high EMG activations in the selected muscles and therefore high activation intensities can be achieved. Thereby, a RV training setting in combination with high frequencies and amplitudes in the forefoot stance seems to be the most favourable parameter selection. (2) WBV training based on the above-mentioned recommendation causes an additional effect on balance control and strength endurance; however the jump performance remains unaffected. In conclusion this study provides evidence for an additional effect of WBV above conventional exercise alone.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.