Cognitive performance is preserved following rapid heat stress exposure in firefighters

This experiment measured the impact of rapid heat stress (RHS) on five cognitive domains: immediate memory, visuospatial perception, expressive language functioning, attention, and delayed memory, using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). RHS refers to a form of uncompensable heat stress characterized by a swift rise in core temperature during exercise while wearing fully encapsulated personal protective equipment (PPE). Our previous research has demonstrated that similar conditions have resulted in specific changes in electroencephalography (EEG), cerebral oxygenation, reaction time, and response inhibition (Coehoorn et al., 2024; Coehoorn et al., 2023; Coehoorn et al., 2020). Here, we hypothesized that RHS would lead to impairments in the five cognitive domains of interest. Thirty male firefighters with at least 5 years of fire service experience performed a steady-state walking treadmill protocol in an environmental chamber (35-36 °C; 50% humidity) while wearing firefighter PPE until they either completed the protocol, reached a core temperature of 39 °C, or achieved a volitional maximum. The five domains were measured pre- and post-heat stress using the RBANS. There were no significant changes (p > 0.05) in the five domains of neurocognitive status. These findings suggest that, under the present experimental conditions, RHS exposure does not impair cognitive performance in firefighters. This may reflect task characteristics, the timing of the assessment, or the level of physiological strain achieved. Future research must consider these factors when evaluating heat-related performance effects among firefighters.