Tndon vibration does not alter recovery time following fatigue

Tendon vibration has been shown to enhance muscle activity and to increase muscular endurance times. The impact of vibration on recovery from fatigue, however, is not known. This study aims to determine whether tendon vibration reduces recovery time following fatiguing contractions.

Eight sedentary males (22 ± 2.8 yr) performed a fatiguing protocol of ankle dorsiflexor muscles on two separate days, with a minimum of 48 h between visits. Surface EMG was recorded from the tibialis anterior muscle while participants were performing 25 maximal voluntary contractions (MVCs), each lasting 5 s and separated by 2 s. Following the fatiguing protocol, recovery was assessed with 3-s MVC each minute over a 10-min period. Recovery time was defined as the time at which force had returned to 90% of baseline values. At one visit, vibration was applied to the distal tendon of the tibialis anterior muscle between MVCs (throughout recovery). The alternate visit involved a sham condition in which no vibration was applied.

MVC force (P = 0.48) and EMG amplitude (P = 0.26) were not significantly different across testing days. Both MVC force (P < 0.001) and EMG amplitude (P < 0.001) declined significantly at the end of the fatigue protocol. However, there were no significant interaction effects for MVC force (P = 0.82) or EMG amplitude (P = 0.09), indicating similar levels of fatigue across days. With tendon vibration, MVC force recovered within 4.0 ± 2.5 min, which was not different from the sham condition (5.3 ± 1.8 min; P = 0.42). Similarly, EMG recovery time was not different between vibration condition (3.9 ± 3.8 min) and sham condition (4.9 ± 2.5 min) (P = 0.41).

These results suggest that activation of excitatory group Ia afferents through tendon vibration does not substantially alter recovery time following fatigue.