Effects of Horizontal Whole-Body Vibration on Electrical Sensory Threshold in Healthy Young Adults

Background: This study investigated changes in electrical sensory threshold (ST) following horizontal whole-body vibration (WBV) and compared these effects with passive relaxation. Additionally, the influence of sex, age, and body composition on baseline ST and the WBV-induced immediate changes in ST was evaluated. Methods: The study comprised a preliminary controlled phase including participants exposed to WBV (n = 44) or passive relaxation (n = 44), followed by a main phase involving 266 healthy young adults (147 women, 119 men). ST was assessed before and after a 30 min WBV session or passive relaxation using transcutaneous electrical stimulation. Results: WBV significantly increased ST in the preliminary phase (13.75 to 16.00 mA, p < 0.001, r = 0.65), whereas passive relaxation produced the opposite effect, significantly decreasing ST (13.00 to 10.00 mA, p < 0.001, r = 0.84). In the main phase, WBV resulted in an increase in ST in both women (14.00 to 15.50 mA, p < 0.001, r = 0.48) and men (16.00 to 18.50 mA, p < 0.001, r = 0.43). Women exhibited lower ST than men both before and after WBV, although the magnitude of the WBV-induced response was comparable between the sexes. Statistically significant associations between body composition and baseline ST were observed in women, whereas no significant associations were identified in men. A weak positive association between age and the WBV response was observed in women, whereas no significant association was found in men. Conclusions: Horizontal WBV induces an immediate increase in electrical ST, suggesting an immediate effect on somatosensory processing. Baseline ST and the immediate ST response to WBV exhibited different patterns of association with age and body-composition parameters. Because these analyses were exploratory, the findings should be considered hypothesis-generating and require confirmation in future studies.