Leg muscle activity level and rate of perceived exertion with different whole-body vibration frequencies in multiple sclerosis patients: An exploratory approach

This study aimed to determine the whole-body vibration (WBV) frequencies that cause the highest average electromyogram (EMG) output in four different muscles, in relation to patients suffering from multiple sclerosis (MS), and to what extent the loads were acceptable. In a series of measures using different WBV frequencies applied to five MS patients, the effects on EMG output (in μV) and the rate of perceived exertion (RPE; scale, 6–20) were studied. All measurements were performed on two different WBV devices: the ZeptorMed™ and the Galileo2000®. The physical loads were well accepted, with a highest average rate of perceived exertion of 12.8 during the 29-Hz application. With the Galileo2000®, the highest EMG results were obtained at 29 Hz in the vastus medialis and lumbar muscles, at 25 Hz in the gastrocnemius medialis, and at 19 Hz in the tibialis anterior muscle. The results with the ZeptorMed™ were more consistent at 11 Hz and 12 Hz, but the EMG output was lower. In conclusion, the physical loads of WBV were well accepted by the MS patients. However, the most effective frequencies are device specific and should be determined for each subject and for each individual muscle or muscle group.