The VO(2) response at the onset of severe intensity exercise

Fourteen participants achieved a peak VO(2) of 2573 +/- 738 ml á min-1 in approximately 3 1/2-min cycle ergometer tests. However, in the first 45 s of exercise, formal description of the phase II of the V(O)2 response indicated that the V(O)2 was projecting toward a value of 3451 +/- 1599 ml x min(-1), well above the peak VO(2)peak and not different from the predicted O(2) demand of 3389 +/- 800 ml x min(-1). We conclude that, at the onset of exercise in the severe intensity domain, VO(2) is initially driven toward the O(2) demand, and then is limited by the achievable VO(2) (VO(2peak)).