Whole body vibration may have immediate adverse effects on the postural sway of stroke patients

[Purpose] This study applied whole body vibration (WBV) at different vibration frequencies to chronic stroke patients and examined its immediate effect on their postural sway. [Subjects and Methods] A total of 14 (5 males, 9 females) stroke patients participated. The subjects were randomly assigned to one of the two vibration frequency groups (10 Hz and 40 Hz). Right before and after the application of WBV, the subjects performed quiet standing for 30 seconds, and COP parameters (range, total distance, and mean velocity) were analyzed. [Results] The 10 Hz WBV did not affect the postural sway of stroke patients. The 40 Hz WBV increased postural sway in the ML direction. [Conclusion] The results suggest that WBV application to stroke patients in the clinical field may have adverse effects and therefore caution is necessary.