Aerobic exercise (AE) and transcranial direct current stimulation (tDCS) are priming techniques that have been studied for their potential neuromodulatory effects on corticomotor excitability (CME), however the synergistic effects of AE and tDCS are not explored in stroke. Here we investigated the synergistic effects of AE and tDCS on CME, intracortical and transcallosal inhibition, and motor control for the lower limb in stroke. 26 stroke survivors participated in three sessions - tDCS, AE and AE + tDCS. AE included moderate intensity exercise and tDCS included 1 mA of anodal tDCS to the lower limb motor cortex with or without AE. Outcomes included measures of CME, short interval intracortical inhibition (SICI), ipsilateral silent period (iSP) (an index of transcallosal inhibition) for the tibialis anterior and ankle reaction time. Ipsilesional CME significantly decreased for AE compared to AE + tDCS and tDCS. No differences were noted in SICI, iSP measures or reaction time between all three sessions. Our findings suggest that a combination of exercise and tDCS, and tDCS demonstrate greater excitability of the ipsilesional hemisphere compared to exercise only, however these effects were specific to the descending corticomotor pathways. No additive priming effects of exercise and tDCS over tDCS was observed.
Novelty:
• An exercise and tDCS paradigm upregulated the descending motor pathways from the ipsilesional lower limb M1 compared to exercise.
• Exercise or tDCS administered alone or in combination did not affect intracortical or transcallosal inhibition or reaction time.
Transcranial Direct Current Stimulation over Bi-Lateral motor Cortices shows No Effect on Simple Visual Motor Reaction Time
