No Alteration of the Neuromuscular Performance of Plantar-Flexor Muscles After Achilles Tendon Vibration

Abstract

Context: Prolonged tendon vibration may induce muscle fatigue, as assessed by a decrease in maximal force production. It remains unknown, however, whether the decrease in muscle strength after prolonged Achilles tendon vibration is related to the vibration frequency. Objective: To assess the maximal capacity of plantar-flexor (PF) neuromuscular function before and after prolonged Achilles tendon vibration at low and high frequencies generated using a portable device. Design: Pre- and posttest intervention with control. Setting: University laboratory. Participants: 10 healthy men age 22.6 ± 4.0 y. Intervention: Each subject participated in 3 experimental sessions that were randomly distributed and separated by 1 wk. During each experimental session, 1 of the following vibration protocols was applied for 30 min: 40-Hz vibration, 100-Hz vibration, or no vibration (control protocol). Main Outcome Measures: Maximal-voluntary-contraction torque, voluntary activation level, twitch torque, maximal electromyographic activity, and maximal M-wave of PF muscles (measured before and after each vibration or control protocol). Results: Statistical analysis exhibited no significant effect of vibration protocol on the measured variables. Conclusions: The current study demonstrates that 30 min of Achilles tendon vibration at a low or high frequency using a portable stimulator did not affect the neuromuscular performance of the PF muscles. These results emphasize the limits of tendon vibration, whatever the frequency applied, for inducing neuromuscular fatigue.