View article

Increasing ventilation (V ̇ e) during hypoxic exercise may help to defend arterial O₂ saturation (Sa_O2) and V ̇ _{O 2max} , however, many athletes experience limitations to ventilatory flow and are not able to increase V ̇ e at high workrates. Five of 19 highly trained endurance athletes screened had <5% of their tidal flow–volume loop during maximal exercise meet the boundary set by their maximal resting flow–volume loop. These five athletes were grouped as non-flow limited and compared to the five athletes who demonstrated the greatest percent of tidal volume flow limitation (56±11%) during maximal exercise (flow limited). Each athlete completed two incremental treadmill tests to exhaustion: normoxia and hypoxia (Fi_O2=0.187). Non-flow limited athletes increased V ̇ e at V ̇ _{O 2max} from normoxia to hypoxia (140.9±13.4 vs. 154.7±11.9 L/min, P<0.05), while flow limited athletes did not (159.5±9.4 vs. 162.3 …