Effect of internal and external cooling on high‐intensity intermittent cycling performance and cognitive function in the heat

We investigated the effect of internal and external cooling on high‐intensity intermittent cycling performance and cognitive function in the heat. Twenty‐nine males completed a control trial (CON) and a cooling trial (ice slurry and ice collar; COOL) in the heat (33°C, 50% relative humidity) involving a 40 min intermittent cycling protocol (two sets of ten 2 min stages, each consisting of 5 s sprint, 105 s active recovery and 10 s rest). A battery of cognitive tests was completed pre‐ and postexercise, with physiological and perceptual responses recorded throughout. No differences in peak or mean power output were found between conditions (all p > 0.05). Average trial rectal (COOL: 37.39°C ± 0.59°C; CON: 37.59°C ± 0.56°C, p < 0.001) and neck (COOL: 28.87°C ± 4.87°C; CON: 32.82°C ± 1.43°C, P < 0.001) temperatures were found to be lower in COOL. Participants reported feeling better and reported lower ratings of thermal sensation and improved comfort in COOL (all p < 0.05). Response times on the Stroop task complex level were quicker over time in COOL (COOL: −48 ± 23 ms; CON: −11 ± 18 ms, p = 0.002) and quicker overall on the number level of Sternberg during COOL (COOL: 434 ± 77 ms; CON: 437 ± 84 ms, p = 0.046). However, over time, the improvement in response times on the number level of Sternberg was greater in CON (COOL: −6 ± 3 ms; CON: −26 ± 2 ms, p = 0.015). Response times became quicker over time to a greater extent in CON on the visual search complex level (COOL: −15 ± 1 ms; CON: −119 ± 31 ms, p = 0.009). The combined cooling intervention did not influence sprint performance and had only a minimal influence on some domains of cognitive function but did lead to improvements in physiological and perceptual responses. These findings provide information on a practical combined cooling method that can be implemented in elite sport.