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 plantarflexor (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. Prolonged muscle or tendon vibration may induce fatigue, as assessed by a decrease in maximal-voluntary-contraction (MVC) strength, 1-6 even though some investigations reported no fatigue effect. 7,8 Ushiyama et al 3 found a significant decrease in plantar-flexor (PF) MVC strength (-16.6%) after 30 minutes of Achilles tendon vibration at 100 Hz, using a fixed mechanical stimulator. Those authors observed that the reduction in MVC strength was due to an attenuation of Ia afferent activity leading to a decrease in muscle activity that was more pronounced for the gastrocnemii than for the soleus muscle. 3 Nevertheless, some questions related to this finding remain to be clarified. First, when vibration is applied to the quadriceps muscle for 30 minutes, the reduction in MVC strength is greater at low frequency (30 Hz) than at high frequency (120 Hz). 2 Roll et al 9 observed that muscle-spindle primary afferents are stimulated, with a 1-to-1 discharge rate, by vibration frequencies up to 100 Hz, but frequencies above 100 Hz impaired the relationship. They showed that vibration frequency is optimal between 80 and 100 Hz, that is, high-frequency vibration, to activate the primary endings of the muscle spindle, while secondary endings can be recruited in the 20-to 60-Hz vibration range, that is, low-frequency vibration. Consequently, it remains unknown whether the decrease in muscle strength after prolonged Achilles tendon vibration is related to high (ie, involving Ia afferent acti...

Acute effect of tendon vibration applied during isometric contraction at two knee angles on maximal knee extension force production

“…This indicates that the fatigue-related combined exercise at a 90˚knee angle was only the result of submaximal contractions but not of the tendon vibration. The lack of effect of muscle/tendon vibration on neuromuscular performance is in agreement with some reports for ankle plantar flexor [14,16], ankle dorsiflexor [15] and KE muscles [13]. However, this remains in contrast with other works in which it was observed that prolonged muscle/tendon vibration altered the maximal motor performance of several muscle groups, such as KE muscles [1,2,4,5,[7][8][9][10].…”

“…It is classically defined as being proximal (central fatigue) or distal (peripheral fatigue) to the neuromuscular junction, even if neuromuscular fatigue results from a complex interaction between both central and peripheral fatigue [11]. After prolonged vibration, it has been reported that peripheral mechanisms are rarely altered [3,[6][7][8][13][14][15][16], suggesting that the decrease in MVC force is mainly explained by neural alterations. In this context, previous studies showed an attenuation of Ia afferent function [1,2,5,7,8], supported by reductions in spinal loop excitability, as evidence by H-reflex measurement [13,14].…”

“…Indeed, recent investigations did not reveal a significant effect of tendon vibration on maximal motor performance for muscle groups crossing the ankle or the knee joints [13][14][15][16]. Although experimental parameters such as the vibration frequency used [1,16] have been examined in the literature to maximize fatigue effect following prolonged tendon/ muscle vibration, other factors need to be explored such as muscle activity (i.e. contraction) or joint angle (i.e.…”

An Acute Exposure to Muscle Vibration Decreases Knee Extensors Force Production and Modulates Associated Central Nervous System Excitability

“…The ability to produce a maximal level of voluntary force depends on both peripheral and central mechanisms. Evidence based on electrically-evoked twitch (Ushiyama et al, 2005 ; Herda et al, 2009 ; Fry and Folland, 2014 ; Saito et al, 2016a , b ) and M-wave amplitudes (Ushiyama et al, 2005 ; Ekblom and Thorstensson, 2011 ; Fry and Folland, 2014 ; Cattagni et al, 2016 ; Farabet et al, 2016 ; Saito et al, 2016a , b ) seems to rule out an influence of peripheral mechanisms on the MVC decrease commonly seen following prolonged LV. Our results further confirm this interpretation, as there were no differences between CON and LV for: (i) M-wave areas evoked on either relaxed or contracted muscles; and (ii) potentiated peak twitch.…”

Effect of Different Local Vibration Durations on Knee Extensors’ Maximal Isometric Strength

“…At rest, prolonged exposure (20-30 min) to LV on the plantar flexor [10][11][12] or knee extensor muscles [13][14][15][16][17][18], in most cases, leads to a loss of strength (for a review, refer to [19]), even though several studies have failed to demonstrate this effect [20][21][22][23]. The primary cause of this fatigue could be an intramuscular (peripheral) alteration beyond the neuromuscular junction [24,25].…”