High level runners are able to maintain a VO2 steady-state below VO2max, in an all-out run over their critical velocity

During prolonged and intense running exercises beyond the critical power level, a (V) over dot O-2 slow component elevates (V) over dot O-2 above predicted (V) over dot O-2-work rates calculated from exercise performed at intensities below the lactate threshold. In such cases, the actual (V) over dot O-2 value will increase over time until it reaches (V) over dot O-2max. The aims of the present study were to examine whether the (V) over dot O-2 slow component is a major determinant of (V) over dot O-2 over time when running at a speed beyond critical velocity, and whether the exhaustion latency period at such intensity correlates with the magnitude of the (V) over dot O-2 slow component. Fourteen highly trained long-distance runners performed four exhaustive runs, each separated by one week of light training. (V) over dot O-2 and the velocity at (V) over dot O-2max (v(V) over dot O-2max) were determined for each by a graded treadmill exercise. The critical velocity (86.1 +/- 1.5% v(V) over dot O-2max) of each runner was calculated from exhaustive treadmill runs at 90, 100 and 105% of v(V) over dot O-2max. During supra-critical velocity runs at 90% of v(V) over dot O-2max, there: was no significant rise in (V) over dot O-2max (20.9 +/- 2.1 mi min(-1) kg(-1) between the third and last min of tlim 90), such that the runners reached a (V) over dot O-2 steady-state, but did not reach their v(V) over dot O-2max level over time (69.5 +/- 5.0 vs 74.9 +/- 3.0 ml min(-1) kg(-1)). Thus, subjects' time to exhaustion at 90% of v(V) over dot O-2max was not correlated with the (V) over dot O-2max slow component (I = 0.11, P = 0.69), but significantly correlated with the lactate threshold (r = 0.54, P = 0.04) and the critical velocity (% v(V) over dot O-2max; r = 0.65, P = 0.01). In conclusion, the present study demonstrates that for highly trained long-distance runners performing exhaustive, supra-critical velocity runs at 90% of v(V) over dot O-2max, there was not a (V) over dot O-2 slow component tardily completing the rise of (V) over dot O-2 Instead, runners will maintain a (V) over dot O-2 steady-state below (V) over dot O-2max, such that the time to exhaustion at 90% of v(V) over dot O-2max for these runners is positively correlated with the critical velocity expressed as % of v(V) over dot O-2max.