Baseline Measures of Cortical Inhibition Predict Motor Performance Changes after Exercise Interventions

Research Objectives: To investigate the relationship of transcranial magnetic stimulation (TMS) measures on cortical inhibition before and after an exercise intervention in older adults. Our hypothesis is that higher levels of cortical inhibition would predict greater motor skill acquisition. We predicted that persons randomized to an aerobic spin exercise intervention would increase cortical inhibition and motor performance as compared to light strength training.

Design: The study design is randomized controlled trial with two groups investigating a balance and strength training intervention (both lasting 12-weeks or 36 sessions) against an Aerobic Cycling Intervention. The assessment sessions included behavioral testing, TMS taken at study baseline and after 12-weeks.

Setting: This project involved community dwelling older adults and was performed in a medical center. The main study sites were the Atlanta VA and Emory University.

Participants: We randomized 20 participants to either an exercise intervention or a balance and strength training group after obtaining informed consent. Participants were required to be over the age of 60 years and reportedly healthy at inclusion. This report is on 13 completers.

Interventions: Participants were randomized to either a 12-week interval aerobic spin cycling (HIIT spin) or a 12-week intervention involving light strength training both under supervised trainers thrice weekly for up to 45 minutes per session.

Main Outcome Measures: We acquired transcranial magnetic stimulation measures of: cortical excitability (motor threshold), Short intracortical inhibition, Long Intracortical Inhibition, Short Interhemispheric inhibition, long interhemispheric inhibition. Speed and accuracy of motor learning was the behavioral outcome.

Results: Baseline measures of SICI and LICI showed participants with higher levels of disinhibition showed better motor performance. We found no effect for group. Contrary to our hypothesis, individuals with greater increases in TMS inhibition showed lower motor skill performance after interventions.

Conclusions: We can conclude from the preliminary data that measures of cortical inhibition taken from TMS do show change associated with interventions in older adults and predict improvement in motor skill acquisition. Additional study is needed to identify the mechanisms of change in cortical inhibition.

Author(s) Disclosures: None.