Reduced oxygen availability during high intensity intermittent exercise impairs performance

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Abstract
This study examined the influence of reduced oxygen availability on the ability to perform repeated bouts of high intensity exercise on a cycle ergometer. Seven male physical education students performed 10 exercise bouts (of 6 s each), interspersed with 30-s recovery periods, under hypoxic and normoxic conditions. The hypoxic condition was carried out in a low pressure chamber at 526 mmHg. Subjects were instructed to try to maintain a target pedalling speed of 140 rev min-1 during each exercise period. The mean power output of the first exercise bout was ˜ 950 W. In both experimental conditions, all subjects were able to maintain the target speed for the first 3 s of each of the 10 exercise bouts. During the last 3-s interval of each exercise period the target speed was not maintained in both conditions over the 10 sprints. However, the reduction was greater in the hypoxic condition (P < 0.05). Post-exercise blood lactate accumulation was higher with hypoxia [10.3 (0.7) vs. 8.5 (0.8) mmol 1-1P < 0.05]. Oxygen uptake, measured during the exercise and recovery periods of sprints 6–9, was lower in the hypoxic condition [3.03 (0.2) vs. 3.19 (0.2) 1 min-1, P < 0.05], These results indicate that a reduction in oxygen availability during high intensity intermittent exercise results in a higher accumulation of blood lactate and a lower oxygen uptake. The ability to maintain a high power output is impaired.

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