The goal of this clinical trial is to determine the effects of different hypoxia exposures (FiO2 = 11%, 13%, 15%, and 21%) on cognitive performance in healthy adults. The main questions it aims to answer are:

• What is the best hypoxia exposure to improve reaction time, anticipation, attention and memory tasks?
• Which hypoxia exposure causes the greatest detriments in cognitive function?

Participants will completed four trials in a single-blinded crossover randomised control trial. In the first session, individuals familiarised with the different cognitive tests and hypoxic exposures. In the next four experimental trials (separated by 1 week), participants arrived at the laboratory and rested in a seated for 10 min. The vital signs (i.e., SpO2, HR, blood pressure) and Lake Louise Score were recorded prior to mask placed and start with in one of the four conditions: a) PLA/NOR, b) FiO2=15%, c) FiO2=13% or FiO2=11%. In this hypoxic condition the participant will spend a total of 45 min, of which 30 min was at rest, and the other 15 min was performing the cognitive tasks (i.e., memory test, go/no-go test, eriksen flanker test, anticipation task and reaction time test).

Inclusion Criteria:

• Physically active individuals ( >150 min/week moderate physical activity or >75 min/week vigorous physical activity)
• Non-smokers
• Individuals without serious and undiagnosed health problems

Exclusion Criteria:

• Pregnancy and/or breastfeeding
• Residing at an altitude of more than 1300 m
• Having been exposed to an altitude of more than 900 m in the last 8 months
• Having performed a study with hypoxia in the last 8 months
• Suffering from any of the following diseases/pathologies: diabetes, sleep apnoea, dyslexia, colour blindness, blurred vision, respiratory and/or neuromuscular diseases.