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 V̇O 2 slow component elevates V̇O 2 above predicted V̇O 2 -work rates calculated from exercise performed at intensities below the lactate threshold. In such cases, the actual V̇O 2 value will increase over time until it reaches V̇O 2max. The aims of the present study were to examine whether the V̇O 2 slow component is a major determinant of V̇O 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 V̇O 2 slow component. Fourteen highly trained long-distance runners performed four exhaustive runs, each separated by one week of light training. V̇O 2 and the velocity at V̇O 2max (vV̇O 2max) were determined for each by a graded treadmill exercise. The critical velocity (86.1 ± 1.5%vV̇O 2max) of each runner was calculated from exhaustive treadmill runs at 90, 100 and 105% of vV̇O 2max. During supra-critical velocity runs at 90% of vV̇O 2max, there was no significant rise in V̇O 2max (20.9 ± 2.1 ml min -1 kg -1 between the third and last min of tlim 90), such that the runners reached a V̇O 2 steady-state, but did not reach their vV̇O 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 vV̇O 2max was not correlated with the V̇O 2max slow component (r = 0.11, P = 0.69), but significantly correlated with the lactate threshold (r = 0.54, P = 0.04) and the critical velocity (% vV̇O 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 vV̇O 2max, there was not a V̇O 2 slow component tardily completing the rise of V̇O 2. Instead, runners will maintain a V̇O 2 steady-state below V̇O 2max, such that the time to exhaustion at 90% of vV̇O 2max for these runners is positively correlated with the critical velocity expressed as % of vV̇O 2max.