REDUCED OXYGEN AVAILABILITY DURING HIGH-INTENSITY INTERMITTENT EXERCISE IMPAIRS PERFORMANCE

This study examined the influence of reduced oxygen availability on th e ability to perform repeated bouts of high intensity exercise on a cy cle ergometer. Seven male physical education students performed 10 exe rcise bouts (of 6 s each), interspersed with 30-s recovery periods, un der hypoxic and normoxic conditions. The hypoxic condition was carried out in a low pressure chamber at 526 mmHg. Subjects were instructed t o try to maintain a target pedalling speed of 140 rev min-1 during eac h exercise period. The mean power output of the first exercise bout wa s similar to 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 spr ints. However, the reduction was greater in the hypoxic condition (P < 0.05). Post-exercise blood lactate accumulation was higher with hypox ia [10.3 (0.7) vs. 8.5 (0.8) mmol 1(-1), P < 0.05]. Oxygen uptake, mea sured during the exercise and recovery periods of sprints 6-9, was low er 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 accumu lation of blood lactate and a lower oxygen uptake. The ability to main tain a high power output is impaired.