High-intensity Interval Training Enhances Corticospinal Excitability And Motor Learning

High intensity interval training (HIIT) is effective in modulating brain excitability. This effect on neuroplasticity is thought to promote the learning and retention of motor skills. However, it is unclear whether the timing of HIIT with respect to the training of the motor skill can aid in its acquisition and retention. PURPOSE: To examine the effect of HIIT on motor learning when performed before vs after multiple sessions of motor task practice, and to examine the effect of HIIT on corticospinal excitability (CSE) and intracortical networks. METHODS: 28 participants (16 F) performed 4 sessions of HIIT (3 sets of 3 min at 90% maximal power output (POmax) separated by 2 min at 50% POmax). During session 1 participants performed a maximal graded exercise test to determine their POmax, which was used to determine workload for the HIIT sessions. HIIT-mediated changes in CSE and intracortical networks were assessed by transcranial magnetic stimulation, a form of non-invasive brain stimulation, during session 2. During sessions 3-5, either before or after HIIT, participants trained on a complex motor skill requiring them to reproduce trajectories on a touchscreen, where learning was confirmed via a decrease in performance error across training sessions. RESULTS: Using Bayesian linear mixed effects modeling a credible difference in performance was observed between the HIIT groups by the third session, where the group who performed HIIT after task practice showed improved learning when compared to the group performing HIIT before (probability distribution (pd) = 95.4%, d = 0.22; Fig 1). Further, HIIT was shown to drive an increase in CSE both immediately after (pd = 98.44%, d = 0.30) and 30 minutes after the exercise session (pd = 99.25%, d = 0.30; Fig 1). CONCLUSION: This study supports the use of HIIT for motor learning through consolidation of a motor skill, and that HIIT-mediated changes in CSE and intracortical networks are a likely mechanism underlying the effect.