Effect of whole body vibration applied on upper extremity muscles

The acute residual effect of whole body vibration (WBV) on upper extremity muscles and testosterone secretion was studied. Eight highly (G1), nine moderately trained gymnasts (G2) and seven physically active persons (CG) were recruited for the investigation. The intervention occurred in push-up position with the elbow flexed at 90°. G1 and G2 received 30 s, 30 Hz and 6 mm amplitude vibration repeated five times. Subjects were tested before and after one and ten minutes intervention in push-up movement. Contact time (Tc), fly time (Tf), TF/Tc ratio and impulse was measured from the ground reaction force-time curves recorded during self-selected (SSRM) and full range of motion (FRM). Testosterone level in urine was also determined. Tf increased significantly in SSRM for G1 and decreased in SSRM and FRM for G2. Tf/Tc ratio in FRM and impulse in SSRM increased significantly for G1 only. No significant alteration in testosterone level was observed. We concluded that WBV is a reasonable training modality for influencing dynamic work of upper extremity muscle, but the reaction to WBV is training and individual dependent. It seems that WBV do not influence dynamic work through increased testosterone secretion because of the relatively low mass of the involved muscles.

Effects of individualized whole-body vibration on muscle flexibility and mechanical power

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.