Introduction: The adequate development of intracortical inhibitory processes seems crucial for an intact motor control. With respect to balance, it was previously shown that healthy adults, both young and old, decrease short interval intracortical inhibition (SICI) when they perform challenging postural tasks (Papegaaij et al., 2015). However, the level of SICI is generally lower in elderly, who - at the same time - display worse balance skills than young subjects (Papegaaij et al., 2014). Therefore, we asked the question whether improvements in postural control due to balance training are accompanied by increased intracortical inhibition when tested during the performance of challenging postural tasks. Methods: For this purpose, a training group (TG, practiced 6 trainings of 1 hour on a movable platform, n = 13) and a control group (CG, n = 13) were measured with transcranial magnetic stimulation (TMS). Two pulses with an interstimulus interval of 2.5ms were elicited in order to assess SICI during three postural tasks: standing, standing on a movable platform that was partly secured with elastic straps (straps), or that was freely moving (free). During each postural task, 20 single and 20 paired pulses were elicited by TMS in the soleus (SOL) and tibialis (TA) muscles. Results: The TG significantly improved the time in balance by 80% after the training, whereas the CG increased the time in balance by 21%. The SOL did not reveal significant main effects or interactions for SICI, whereas the TA, showed significant increase of SICI by 22% for the TG abut a reduction of 12% for the CG: main effect of POSTURAL TASKS (F2, 48 = 24.6; p < 0.001), and TIME x GROUP interaction (F1, 24 = 5.9; p = 0.02). The increase in balance performance was correlated to an in intracortical inhibition (r = 0.478, p = 0.021) in the TA muscle. Discussion: The purpose of this study was to evaluate whether balance training induced changes in postural control are accompanied by increased SICI. In summary, two weeks of balance training significantly improved postural skills in young adults. At the same time, an enhancement of SICI was observed in the TA and was correlated with the improvement in balance performance. This is an important finding, as it shows for the first time that neural adaptations induced by balance training were correlated with enhanced intracortical inhibition. This suggests that intracortical inhibitory processes may play an important role in the control and adaptation of upright posture.
© Copyright 2016 21st Annual Congress of the European College of Sport Science (ECSS), Vienna, 6. -9. July 2016. Veröffentlicht von University of Vienna. Alle Rechte vorbehalten.