EFFECTS OF DIFFERENT WHOLE BODY VIBRATION FREQUENCIES ON THE MAXIMAL ISOMETRIC FORCE GENERATED BY QUADRICEPS MUSCLES

Abstract

Purpose. Whole Body Vibration (WBV) might be considered an alternative to the traditional resistance training methods. This study was aimed at investigating the effects of three different WBV frequencies on the maximum isometric knee extensor strength in untrained adults. Methods. Twenty volunteers participated in this study. They were all students enrolled at the Babes-Bolyai University of Cluj-Napoca. The participants were exposed to vertical vibrations, generated by the Fitvibe Excel Pro vibration platform, with frequencies of 30, 50 and 60 Hz, respectively. Mean forces were recorded for both legs, with the KIN-COM isokinetic dynamometer, over 5 s long time intervals of maximal isometric voluntary contractions of the knee extensor muscles, before and after bouts of 60 s of WBV training. Results. Mean isometric force of the right quadriceps muscles after exposure to a 30 Hz vibration frequency was 656.90 +/- 214.86 N, mean isometric force of the right quadriceps muscles after exposure to a 50 Hz vibration frequency was 645.10 +/- 220.21 N, and mean isometric force of the right quadriceps muscles after exposure to a 60 Hz vibration frequency was 653.65 +/- 206.93 N. Significant changes in isometric knee extensor strength were found between males and females both pre and post-WBV. No significant changes were found between pre- and post-WBV force values for the whole group of participants. Conclusions. There was no enhancement in muscular performance after one bout of 60 s of WBV in healthy adults. More research is needed on the potential effects of short term WBV exposure among untrained adults.