Objective

It has been recently proposed the use of vibration as a neuromuscular rehabilitation technique. A recent study showed significant strength improvement after 14 days of local vibration training on the Achilles tendon. An improvement of the motor drive from the cortical level has been proposed to be one of the mechanisms involved. The aim of the current study was to assess the effects of an 8-week local vibration training (24 sessions of 1 h each) on:

– the maximal voluntary contraction (MVC);

– the cortical voluntary activation (VATMS) assessed using transcranial magnetic stimulation (TMS) technique for the tibialis anterior (TA) muscle.

Material/patients and methods

Forty-four healthy subjects ( n = 22 for both training and control groups) participated in this study. Force measurements were performed during voluntary isometric dorsiflexion with knee and ankle angles fixed at 120 and 90°, respectively. During MVCs, the use of TMS allowed VATMS assessment as follow:

VATMS = (1 – [SITMVC/ERT] × 100) where SITMVC is the superimposed twitch evoked during MVC, and ERT the estimated resting twitch determined by linear regression of the relation between SIT amplitude evoked when TMS was delivered at 100, 75 and 50% MVC and voluntary force. This relation was then extrapolated and the y -intercept was interpreted as the ERT amplitude.

Results

MVC was increased after the 8 weeks of local vibration training (+10.2 ± 11.6%, P = 0.0001). VATMS was also significantly increased (+4.9 ± 9.2%, P = 0.002). No significant variation was reported for the control group neither for MVC ( P = 0.73) or VATMS ( P = 0.99).

Discussion–conclusion

Local vibration training appears as an effective method to induce corticospinal adaptations. Thus, such a technique may have a practical relevance for preventive and/or rehabilitation intervention.