Abstract
Findings regarding the influence of passive heat exposure on cognitive function remain equivocal due to a number of methodological issues including variation in the domains of cognition examined. In a randomized crossover design, forty-one male participants completed a battery of cognitive function tests [Visual Search, Stroop, Corsi Blocks and Rapid Visual Information Processing (RVIP) tests] prior to and following 1 h of passive rest in either hot (39.6 ± 0.4°C, 50.8 ± 2.3% Rh) or moderate (21.2 ± 1.8°C, 41.9 ± 11.4% Rh) conditions. Subjective feelings of heat exposure, arousal and feeling were assessed alongside physiological measures including core temperature, skin temperature and heart rate, at baseline and throughout the protocol. Response times were slower in the hot trial on the simple (main effect of trial, P < 0.001) and complex (main effect of trial, P < 0.001) levels of the Stroop test (Hot: 872 ± 198 ms; Moderate: 834 ± 177 ms) and the simple level of the visual search test (Hot: 354 ± 54 ms; Moderate: 331 ± 47 ms) (main effect of trial, P < 0.001). Participants demonstrated superior accuracy on the simple level of the Visual Search test in the hot trial (Hot: 98.5 ± 3.1%; Moderate: 97.4 ± 3.6%) (main effect of trial, P = 0.035). Participants also demonstrated an improvement in accuracy on the complex level of the visual search test following 1 h passive heat exposure (Pre: 96.8 ± 5.9%; Post: 98.1 ± 3.1%), whilst a decrement was seen across the trial in the moderate condition (Pre: 97.7 ± 3.5; Post: 97.0 ± 5.1%) (time*trial interaction, P = 0.029). No differences in performance were observed on the RVIP or Corsi Blocks tests (all P > 0.05). Subjective feelings of thermal sensation and felt arousal were higher, feeling was lower in the hot trial, whilst skin temperature, core temperature and heart rate were higher (main effects of trial, all P < 0.001). The findings of the present study suggest that response times for perception and executive function tasks are worse in the heat. An improvement in accuracy on perceptual tasks may suggest a compensatory speed-accuracy trade-off effect occurring within this domain, further highlighting the task dependant nature of heat exposure on cognition.
Highlights
While the negative effects of heat exposure on physical performance are well known (Drust et al, 2005; Morris et al, 2005), data regarding the effects of heat exposure on cognitive performance are less well understood
Response Times Simple Overall, response times were slower in the hot trial [main effect of trial, t(1, 3687) = 4.9, P < 0.01; d = 0.46, small effect], and response times slowed over time [main effect of time, t(1, 3687) = 2.8, P < 0.01]
Response Times Simple Overall, response times were slower in the hot trial [main effect of trial, t(1, 2376) = 5.8, P < 0.01; d = 0.33, small effect] and changed across time [main effect of time, t(1, 2376) = 2.9, P < 0.01]
Summary
While the negative effects of heat exposure on physical performance are well known (Drust et al, 2005; Morris et al, 2005), data regarding the effects of heat exposure on cognitive performance are less well understood. Gaoua et al (2018) has recently provided valuable insight into the mechanisms associated with changes in cognition in response to passive heat exposure, an understanding across a broad range of cognitive domains is still lacking. The use of exercise-induced heating protocols prevents the isolation of heat as a stressor (Racinais et al, 2008). These variables likely contribute to the discrepancies in the literature. This provides rational for a protocol where as many confounding variables (e.g., low intensity exercise) are eradicated and a breadth of cognitive domains can be tested under the same conditions using a large cohort of the same participants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
