Aerobic exercise training selectively improves cortical inhibitory function after stroke

Background Aerobic exercise elicits striking effects on neuroplasticity and cognitive executive function but is poorly understood after stroke. Objective We tested the effect of 4 weeks of aerobic exercise training on inhibitory and facilitatory elements of cognitive executive function and electroencephalography (EEG) markers of cortical inhibition and facilitation. We investigated relationships between stimulus-evoked cortical responses, blood lactate levels during training, and aerobic fitness post-intervention. Methods Twelve individuals with chronic (>6mo) stroke completed an intensive aerobic exercise intervention (40-mins, 3x/week). Electroencephalography and motor response times were assessed during congruent (response facilitation) and incongruent (response inhibition) stimuli of a Flanker task. Aerobic fitness capacity was assessed as VO 2 -peak during a treadmill test pre- and post-intervention. Blood lactate was assessed acutely (<1 min) after exercise each week. Cortical inhibition (N2) and facilitation (frontal P3) were quantified as peak amplitudes and latencies of stimulus evoked EEG activity over the frontal cortical region. Results Following exercise training, the response inhibition speed increased while response facilitation remained unchanged. A relationship between earlier cortical N2 response and faster response inhibition emerged post-intervention. Individuals who produced higher lactate during exercise training achieved faster response inhibition and tended to show earlier cortical N2 responses post-intervention. There were no associations between VO 2 -peak and metrics of behavioral or neurophysiologic function. Conclusions These findings provide novel evidence for selective benefits of aerobic exercise on inhibitory control during the initial 4-week period after initiation of exercise training, and implicate a potential therapeutic effect of lactate on post-stroke cortical inhibitory function. Trial Registration ClinicalTrials.gov Identifier: NCT03760016 . First posted: November 30, 2018. https://clinicaltrials.gov/ct2/show/NCT03760016