Moderate-intensity exercise-induced changes in lactate do not predict changes in corticospinal excitability.

Abstract

INTRODUCTION/PURPOSE Aerobic exercise increases corticospinal excitability (CSE), creating an optimal environment for learning to occur. It has been hypothesized that this may be a result of lactate accumulation in the blood during exercise. However, while prior literature has linked moderate-intensity exercise with enhanced CSE, previous lactate-based work has mainly used maximal or fatiguing exercise. To date, the effect of lactate concentration on CSE during steady-state moderate-intensity exercise has not been investigated. METHODS Twenty-four participants (13F, mean age 23.7 ± 2.7) attended two separate study sessions. Session 1: Participants completed a maximal graded exercise test on a cycle ergometer. Session 2: Participants completed a moderate-intensity exercise session (20-min of cycling at 60% peak power output). Measures of CSE obtained from the first dorsal interosseous (FDI) muscle were assessed via transcranial magnetic stimulation before, immediately after, and 10-min following the exercise session. Lactate was obtained via blood sample at these same timepoints. RESULTS Linear regression demonstrated that lactate concentration did not predict an exercise-induced change in CSE immediately following exercise (R2 = 0.02184, F(1, 22) = 0.4913, p = 0.4907) or 10-min post-exercise (R2 = 0.02121 F(1, 22) = 0.4767, p = 0.4971). CONCLUSION These results suggest that lactate is not the primary mechanism behind alterations in CSE driven by moderate-intensity exercise.