Aim: The first purpose of the present study was to assess acute, residual and chronic effects of whole-body vibration on hamstring and lower back flexibility through the application of an individual frequency of vibration. The second purpose was to determine whether the applied vibration intervention over time influences flexibility and reactive strength differently.
Methods: Thirty-four young physically active subjects (19 female and 15 male) were randomly assigned to either a Control or a Vibration Group. Lower back and hamstring flexibility was measured using the Stand and Reach Test. The reactive strength was estimated calculating the power in Drop Jump.
Results: During whole-body vibration the relative change in acute flexibility for the Vibration Group (5.30+/-1.67 cm, 284%) reached a level of significance (P=0.038) compared to that of the Control Group (3.14+/-2.11 cm, 84%). Statistically significant differences in residual flexibility between the two groups were found at 6-min after the conclusion of vibration (P=0.034), at which point the Vibration Group showed the maximal relative change to pre-test (6.31+/-3.36 cm, 138%) versus the Control Group (3.06+/-1.87 cm, 20%). Chronic exposure of whole-body vibration did not produce significant changes in flexibility over time (P>0.05), whereas power in the Drop Jump performance of the Vibration Group increased significantly resulting in a benefit of 16% (P=0.019).
Conclusion: The current study shows that individualized whole-body vibration without superimposing other exercises is an effective method of acutely increasing lower back and hamstring flexibility. Furthermore, the applied individualized whole-body vibration over time influences the reactive strength rather than flexibility.