Intracortical Inhibition Increases during Postural Task Execution in Response to Balance Training

Area of Science:

• Neuroscience
• Motor Control
• Motor Learning

Background:

• Intracortical inhibitory modulation is vital for motor control and learning.
• The long-term effects of training on short-interval intracortical inhibition (SICI) are not well understood.
• Previous research indicates SICI decreases with increased postural task difficulty, but the impact of balance training (BT) remains unclear.

Purpose of the Study:

• To investigate whether improvements in postural control following balance training (BT) are associated with changes in SICI.
• To examine the modulation of SICI during progressively challenging postural tasks after a period of BT.

Main Methods:

• A balance training (BT) group and a control (CON) group (n=13 each) underwent a 2-week training intervention.
• SICI was measured in the tibialis anterior muscle using paired-pulse magnetic stimuli.
• Participants performed three postural tasks of increasing difficulty: stable stance, standing on a secured movable platform, and standing on a freely moving platform.

Main Results:

• The BT group demonstrated significantly greater improvements in postural control compared to the CON group, especially in the 'Free' condition (+80% vs. +21%).
• A main effect of postural task showed decreased SICI with increasing difficulty (F(2, 48)=24.6, p<0.001).
• A significant time × group interaction (F(1, 24)=5.9, p=0.02) revealed enhanced SICI in the BT group across all tasks post-training.
• Increased SICI positively correlated with improvements in balance performance (r=0.56, p=0.047).

Conclusions:

• Balance training leads to increased SICI in the tibialis anterior.
• The observed increase in SICI is correlated with enhanced balance performance.
• Changes in SICI play a role in both the control and training-induced adaptation of upright posture.