Purpose: To examine (i) the acute effect of direct vibration on neuromuscular performance with a maximal-effort dynamic resistance exercise and (ii) the acute residual effect of direct vibration training both with and without the resistance exercise.
Methods: Fourteen subjects were exposed to four training conditions in random order: exercise with vibration (E + V); exercise with sham vibration (E + SV); no exercise with vibration (NE + V); and no exercise with sham vibration (NE + SV). The exercise comprised three sets of maximal-effort bicep curls with a load of 70% 1RM. A portable vibrator was strapped onto the skin over the bicep tendon to apply vibration with an amplitude and frequency of 1.2 mm and 65 Hz. Elbow joint angle and bicep EMG were measured both during training and in pre- and posttraining tests. Angular velocity, moment, power, and bicep root mean squared value of EMG (EMGrms) and mean power frequency of EMG (EMGmpf) were determined for the concentric phase. Interday reliability ranged from 0.69 to 0.99.
Results: During training (acute effect) vibration did not enhance mean angular velocity (1.5 vs 1.5 rad·s−1, P = 0.86), peak angular velocity (2.7 vs 2.7 rad·s−1, P = 0.90), mean moment (27.3 vs 27.4 N·m, P = 0.83), peak moment (39.8 vs 39.4 N·m, P = 0.53), mean power (40.3 vs 41.1 W, P = 0.72), peak power (91.9 vs 90.2 W, P = 0.77), or bicep EMGrms (73.9 vs 71.9, P = 0.78). Similarly, after training (acute residual effect) there was no enhancement from vibration in the mechanical and EMG output when the muscle was trained or was rested (P > 0.05).
Conclusion: These findings suggest that direct vibration, with an amplitude of 1.2 mm and frequency of 65 Hz, applied to the bicep muscle tendon, does not enhance neuromuscular performance in maximal-effort contractions during or immediately after training.
1School of Health and Human Performance and 2School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin, IRELAND; and 3Department of Anatomy, University of Bristol, Southwell Street, Bristol, UNITED KINGDOM
Address for correspondence: Kieran Moran, Ph.D., School of Health and Human Performance, Dublin City University, Collins Avenue, Dublin 9, Ireland; E-mail: Kieran.Moran@dcu.ie.
Submitted for publication June 2006.
Accepted for publication October 2006.