Men and women in hypoxia : the influence of tissue oxygenation on repeated-sprint ability

Abstract

This thesis examined the impact of oxygen (O2) availability on prefrontal cortex and muscle tissue oxygenation during repeated-sprint exercise (RSE) in men and women. Men and women matched for initial-sprint mechanical work performed during ten, 10-s sprints (30s of rest) in normoxia (21% FIO2) and acute hypoxia (13% FIO2). Mechanical work and arterial O2-saturation (SPO2) were obtained for every sprint. Oxy- and deoxygenated haemoglobin concentrations (O2Hb, HHb) were obtained via near-infrared spectroscopy. Hypoxia elicited lower SPO2 and work (14.8% & 7.4%, P < 0.05), larger (45.1%, P < 0.05) and earlier reductions in cortical oxygenation, and no differences between sexes. Cortical de-oxygenation and work decrement were strongly correlated (R2=0.85, P < 0.05). Muscle de-oxygenation was greater in men than women (67.3%, P < 0.05). These results show that O2 availability influences cortical oxygenation and performance equally in men and women, and suggest a more efficient muscle O2 uptake in women.