Immediate and sustained effects of intermittent exercise on inhibitory control and task-related heart rate variability in adolescents

OBJECTIVES: To examine the immediate and sustained effects of intermittent exercise sessions at different intensities on inhibitory control and task-related heart rate variability (HRV) in adolescents. DESIGN: Using cluster-randomization, participants from six classes (n=94) were allocated to groups performing 20min of intermittent exercise at moderate (MIE) or high intensity (HIE) and a control group (CON). METHODS: Using a computer-based Flanker task, inhibitory control was assessed in a classroom setting prior to and following exercise as well as 30 and 60min after exercise cessation. At each time point, HRV was recorded via electrocardiography while participants performed the cognitive task. The intermittent exercise sessions were administered in form of a circuit training with a work to recovery ratio of 1:1 in MIE and 2:1 in HIE. RESULTS: The statistical analysis revealed a time by group interaction for Flanker task performance. Based on further examination, significant reductions in reaction time were found from pre to post, to post-30, and to post-60 in MIE only. A time by group interaction was also found for LF/HF ratio, indicating greater increases in HIE and MIE compared to CON. Correlations between change scores in LF/HF ration and task performance were not significant. CONCLUSIONS: In a classroom setting, improvements in inhibitory control and information processing elicited by moderately-intense intermittent exercise are sustained over at least 60min. Changes in task-related HRV follow a different time course, providing no indication that exercise-induced benefits are due to a facilitation of arousal.