Le rôle des réponses cardiovasculaires et respiratoires sur la cognition chez les jeunes et les ainés sains
It is well established that increasing cardiovascular fitness through an appropriate physical exercise program is an effective way to limit ageing-induced cognitive decline. Precise mechanisms of this positive interaction are not clearly understood, but cerebral oxygenation is thought to play a major role. Notwithstanding its numerous theoretical and practical implications, acute response of cerebral oxygenation to physical exercise and its relationship with cognitive function is underemphasized and under-researched. This thesis is dedicated to this question. Recent NIRS studies in young adults have shown that the relationship between cerebral oxygenation and exercise intensity was an inverted U-shape. There exists a threshold beyond which cerebral oxygenation decreases proportionally to exercise intensity. Assuming that cognitive function is mainly determined by cerebral oxygen availability, this typical response should affect cognitive performance. Moreover, the oxygenation threshold should occur at higher exercise intensity in older adults possessing a high fitness level. Prior to clarifying the exact role of cerebral oxygenation in cognitive and physical performance, we first examined how cerebral oxygenation pattern changes during stable continuous exercise. Our findings underscore the existence of a decrease of cerebral oxygenation during steady state exercise in normal conditions and confirm the existence of an inverse relationship between the duration of the steady state cerebral oxygenation and exercise intensity.  After checking these methodological points, it was interesting to test the possible relationship between cognitive function and cerebral oxygenation during exercise in healthy young and old adults. The results show that the decrease in cerebral oxygenation observed during high intensity exercise is linked to a decrease in cognitive performance. Clarifying the effect of exercise intensity on cerebral oxygenation and its relationship to executive performance in this exercise intensity domain might help further understand the basic mechanisms of the effect of aerobic exercise on cognition. This thesis does address the gap in the literature and does investigate the relationship between executive performance and cerebral oxygenation during the whole intensity spectrum. This thesis is also the first to report correlations between cerebral oxygenation and cognition during exercise.
Cognition Cerebral Oxygenation Aging Exercise Stable state