Effects of high-intensity interval training and moderate-intensity continuous training on the functioning of attentional networks and heart rate variability in healthy young adults.

OBJECTIVE

Human attentional mechanisms comprise three distinct networks: alerting, orienting, and executive control. Studies assessing the acute effects of moderate-intensity continuous training (MICT) on these networks have yielded inconsistent results. Similarly, the acute effects of high-intensity interval training (HIIT) on these networks remain unclear. Therefore, this study investigated the effects of HIIT and MICT on the functioning of attentional networks and explored the relationship between heart rate variability (HRV) and these networks in healthy young adults.

METHODS

Thirty-six healthy college students completed HIIT, MICT, and a resting (CON) session in a randomized cross-over design. The HIIT protocol comprised 10 × 1-min bouts at 100 % peak power output (Wpeak) with 1 min of active recovery at 20 % Wpeak. The MICT protocol was applied at 40 % Wpeak for 30 min. Functioning of the attentional networks was assessed post-intervention using the Attention Network Test for Interactions (ANT-I). HRV was recorded pre- and post-exercise/rest and during the ANT-I.

RESULTS

HIIT significantly reduced the alerting function compared to CON ( = 0.017) but enhanced executive control compared to CON ( = 0.001) and MICT ( = 0.002). Following HIIT, immediate reductions in the log-transformed root mean square of successive differences (LnRMSSD) were significantly correlated with alerting (r = 0.554,  = 0.001) and executive control functions (r = 0.412,  = 0.016). Task-related LnRMSSD reductions also correlated with alerting (r = 0.424,  = 0.013) and executive control functions (r = 0.356,  = 0.039).

CONCLUSION

A single session of HIIT selectively modulated the functioning of attentional networks, decreasing alerting function while enhancing executive control. These effects were partly mediated by increased arousal resulting from parasympathetic withdrawal.