Sleep apnoea syndrome is a common disorder responsible for poor sleep quality and repeated oxygen depletion in the blood. Patients suffering from this disease experience a reduction in their endurance, i.e. their ability to make prolonged efforts. This loss of muscular endurance affects breathing in particular. It is known that poor sleep reduces endurance, but it is not knwon whether the repeated lack of oxygen for several hours at night also has this effect. This information could help improve the management of certain acute respiratory illnesses (asthma attacks, respiratory infections, etc.). This project therefore seeks to establish a link between repeated oxygen deprivation and a reduction in the human brain's ability to train respiratory muscles. To this end, the healthy volunteers in this study will perform the same breathing exercise (breathing for as long as possible through a mask that makes inspiration difficult) twice: once after 6 hours' exposure to repeated oxygen deprivation, and once under conditions of normal oxygenation. The order of these exercises will be randomized. These exercises will take place in a special room, a hypoxia chamber, where it is possible to deplete the air breathed in oxygen.