Achilles tendon vibration-induced changes in plantar flexor corticospinal excitability

Abstract

Daily Achilles tendon vibration has been shown to increase muscle force, likely via corticospinal neural adaptations. The aim of the present study was to determine the extent by which corticospinal excitability is influenced during direct Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the soleus (SOL), gastrocnemius medialis (GM) and tibialis anterior (TA) by transcranial magnetic stimulation of the motor cortical area of the leg with and without Achilles tendon vibration at various frequencies (50, 80 and 110 Hz). Contralateral homologues were also investigated. SOL and GM MEP amplitude significantly increased by 226 ± 188 and 66 ± 39%, respectively, during Achilles tendon vibration, without any difference between the tested frequencies. No MEP changes were reported for TA or contralateral homologues. Increased SOL and GM MEP amplitude suggests increased vibration-induced corticospinal excitability independent of vibration frequency.

Modulation of soleus corticospinal excitability during Achilles tendon vibration

“…This increase in corticospinal excitability is in agreement with our previous study (Lapole et al 2015) and is strengthened by vMT being 12 % lower than rMT. A similar result has previously been reported during Fig.…”

“…For each trial of 10 TMS pulses, the three largest responses were averaged to reduce intrasubject variability within each trial. As in our previous studies (Lapole et al 2012(Lapole et al , 2015, we observed that such analysis did not alter the magnitude of the reported vibration-induced changes.…”

“…An increase in corticospinal excitability, indicated by increased MEP size, within seconds of the initiation of vibration of various hand and wrist muscles has been reported (Claus et al 1988;Kossev et al 1999;Siggelkow et al 1999;Steyvers et al 2003). During Achilles tendon vibration, we recently reported similar findings for plantar flexor muscles with increases in soleus (SOL) and gastrocnemius medialis MEP amplitudes by 226 and 66 %, respectively (Lapole et al 2015). Input-output curves (i.e.…”

“…A 50-Hz frequency was chosen since this induced maximal MEP facilitation (Lapole et al 2015). During control conditions (i.e.…”

“…Two separate experiments were conducted. The aim of Experiment 1 was to confirm the previously reported vibration-induced increase in corticospinal excitability (Lapole et al 2015) by determining the effect of tendon vibration on SOL inputoutput curves (Devanne et al 1997;Ridding and Rothwell 1997). In Experiment 2, the intracortical processes SICI and ICF were investigated via paired-pulse TMS (Kujirai et al 1993) and compared to single-pulse TMS.…”