A comparison of the effect of two types of vibration exercise on the endocrine and musculoskeletal system.

BACKGROUND Whole body vibration (WBV) is a novel training intervention but a comparison of different methods of WBV has rarely been performed. AIM To compare the short and medium term effects of two regimens of WBV on endocrine status, muscle function and markers of bone turnover. PATIENTS AND METHODS Over a period of 16 weeks, 10 men with a median age of 33 yrs (range, 29,49), were randomised to stand on the Galileo platform (GP) or Juvent1000 platform (JP) 3 times/wk. The total study duration was 16 weeks with measurements performed in a 4 week period of run-in, 8 weeks of WBV and a 4 week period of washout. These measurements included an assessment of anthropometry, body composition, muscle function and biochemical markers of endocrine status and bone turnover. To assess immediate effects of WBV, measurements were also performed at 60 mins before and 5, 30 and 60 mins after WBV. To assess immediate effects of WBV, measurements were also performed at 60 mins before and 5, 30 and 60 mins after WBV. RESULTS GP at 22 Hz was associated with an immediate increase in serum GH, rising from 0.07 μg/l (0.04,0.69) to 0.52 μg/l (0.06,2.4) (p=0.06), 0.63 μg/l (0.1,1.18) (p=0.03), 0.21 μg/l (0.07,0.65) (p=0.2) at 5 mins, 20 mins and 60 mins after WBV, respectively. An immediate effect was also observed in median serum cortisol which reduced from 316 nmol/l (247,442) before WBV to 173 nmol/l (123,245) (p=0.01),165 nmol/l (139,276) (p=0.02) and 198 nmol/l (106,294) (p=0.04) at 5 mins, 20 mins and 60 mins after WBV, respectively. Median serum CTX reduced significantly after 8 weeks of WBV training in the GP group from 0.42 ng/ml (0.29,0.90) pre-WBV to 0.29 ng/ml (0.18,0.44) at the end of WBV training (p=0.03). Over the 8 weeks, there was a reduction in median serum cortisol in the GP group from 333 nmol/l (242,445) (pre-WBV) to 270 nmol/l (115,323) (WBV) (p=0.04). None of the changes observed in the JP group reached statistical significance. Neither group showed any significant effect on muscle function, IGF-1, testosterone, leptin, CRP, creatine kinase, insulin or other markers of bone turnover. CONCLUSION WBV can stimulate GH secretion, reduce circulating cortisol and reduce bone resorption. These effects are independent of clear changes in muscle function and depend on the type of WBV that is administered.