Acute effects of whole-body vibration on lower extremity muscle performance in persons with multiple sclerosis.

BACKGROUND AND PURPOSE Whole-body vibration (WBV) is a relatively new form of exercise training that may influence muscle performance. This study investigated the acute effects of high- (26 Hz) and low- (2 Hz) frequency WBV on isometric muscle torque of the quadriceps and hamstrings in persons with multiple sclerosis. PARTICIPANTS AND METHOD Fifteen individuals (mean age = 54.6 years, SD = 9.6) with multiple sclerosis and Expanded Disability Status Scale scores ranging from 0 to 6.5 (mean = 4.2, SD = 2.3) participated in this randomized, crossover study. After baseline measures of isometric quadriceps and hamstring muscle torque, subjects were exposed to 30 seconds of WBV at either 2 or 26 Hz. Torque values were measured again at one, 10, and 20 minutes after vibration. Subjects returned one week later to repeat the same protocol at the alternate vibration frequency. RESULTS There were no significant differences in isometric torque production between the 2- and 26-Hz WBV conditions. There was also no significant difference between baseline torque values and those measured at one, 10, and 20 minutes after either vibration exposure. However, there was a consistent trend of higher torque values after the 26-Hz WBV when compared with the 2-Hz condition for both quadriceps and hamstring muscles. DISCUSSION AND CONCLUSION Although not statistically significant, peak torque values for both quadriceps and hamstring muscles were consistently higher after 30 seconds of WBV at 26 vs 2 Hz. Whether WBV presents a viable treatment option as either a warm-up activity or a long-term exercise intervention is yet to be determined. Future studies should include a wider variety of WBV parameters and the use of functional outcome measures.