Dimitri Theurot

Purpose This study investigates the effects of different levels of acute normobaric hypoxia on cognitive function and cerebral oxygenation in healthy young adults. Methods Twenty-four participants aged 18–30 years were exposed to hypoxia with an inspired oxygen fraction (FiO₂) equivalent to 20.9%, 17.44%, 14.5% and 12.7%. They performed different cognitive tasks, including the Stroop test, Corsi blocks (forward and backward), the n-Back task (1-Back and 2-Back), and the Go/No-Go task. Cerebral oxygenation was measured using the near-infrared spectroscopy (NIRS) during each cognitive task. Results In this study, we did not observe any effect of hypoxia on cognitive performance. However, perceived difficulty increased with increasing hypoxia, especially for the Stroop task (p = 0.003, Kendall’s W = 0.208) and Corsi (p = 0.018, Kendall’s W = 0.152). NIRS results showed a progressive increase in deoxyhemoglobin (ΔHHb) and a progressive decrease in oxyhemoglobin (ΔO₂Hb) with increasing hypoxia for all cognitive tasks. There was no effect on total hemoglobin (ΔtHb). Finally, positive correlations were found between pulse oxygen saturation (SpO₂) and ΔTSI% and between SpO₂ and ΔO₂Hb for all tasks, while a negative correlation was observed between SpO₂ and ΔHHb. No correlation was found between SpO₂ or TSI% and cognitive performance. Conclusion In conclusion, cognitive function appears to be unaffected by acute exposure to acute normobaric hypoxia at FiO₂ above 12.7%. These results suggest a complete compensation of oxygenation of the prefrontal cortex region in young healthy subjects.

There are many important sport events that are organized in environments with a very hot ambient temperature (Summer Olympics, FIFA World Cup, Tour de France, etc.) and in hot locations (e.g., Qatar). Additionally, in the context of global warming and heat wave periods, athletes are often subjected to hot ambient temperatures. It is known that exercising in the heat induces disturbances that may provoke premature fatigue and negatively affects overall performance in both endurance and high intensity exercises. Deterioration in several cognitive functions may also occur, and individuals may be at risk for heat illnesses. To train, perform, work and recover and in a safe and effective way, cooling strategies have been proposed and have been routinely applied before, during and after exercise. However, there is a limited understanding of the influences of per-cooling on performance, and it is the subject of the present review. This work examines the influences of per-cooling of different areas of the body on performance in terms of intense short-term exercises (“anaerobic” exercises), endurance exercises (“aerobic” exercises), and cognitive functioning and provides detailed strategies that can be applied when individuals train and/or perform in high ambient temperatures.