Does prefrontal cortex oxygenation mediate executive function during high-intensity exercise? A systematic review of fNIRS studies

The transient hypofrontality hypothesis posits that cognitive resources are deprioritized in favor of motor demands during extreme physical stress, potentially reducing prefrontal cortex (PFC) activation and impairing executive function (EF). Although prior studies have attempted to investigate the effects of PFC oxygenation, measured via functional near-infrared spectroscopy (fNIRS), on EF during high-intensity exercise, the results remain inconclusive. This systematic review examined whether PFC oxygenation plays a mechanistic role in changes in EF performance during high-intensity exercise, focusing on insights from fNIRS studies employing dual-task paradigms. Following PRISMA guidelines, a comprehensive literature search across five electronic databases identified 523 studies, of which five met the inclusion criteria and were included in the final synthesis. All included studies employed dual-task paradigms in which EF was assessed concurrently with high-intensity exercise. Some studies reported EF impairments associated with reduced PFC oxygenation during high-intensity exercise, while others observed stable or increased PFC oxygenation, without significant EF impairments. These inconsistencies may arise from methodological variations, extracerebral confounders, and individual differences. The findings highlight PFC oxygenation as a critical yet context-dependent factor in EF regulation but suggest it may not directly mediate cognitive impairments under such dual-task paradigms. This review supports the need for standardized dual-task protocols, advanced neuroimaging techniques, and multi-modal approaches to better understand the role of PFC oxygenation in the transient hypofrontality effect.