Oxygen kinetics and modelling of time to exhaustion whilst running at various velocities at maximal oxygen uptake

The purpose of this study was to characterise the relationship between running velocity and the time for which a subject can run at maximal oxygen uptake (V˙O2max), (tlimV˙O2max). Seven physical education students ran in an incremental test (3-min stages) to determine V˙O2max and the minimal velocity at which it was elicited (νV˙O2max). They then performed four all-out running tests on a 200-m indoor track every 2 days in random order. The mean times to exhaustion tlim at 90%, 100%, 120% and 140% νV˙O2max were 13 min 22 s (SD 4 min 30 s), 5 min 47 s (SD 1 min 50 s), 2 min 11 s (SD 38 s) and 1 min 12 s (SD 18 s), respectively. Five subjects did not reach V˙O2max in the 90% νV˙O2max test. All the subjects reached V˙O2max in the runs at 100% νV˙O2max. All the subjects, except one, reached V˙O2max in the runs at 120%νV˙O2max. Four subjects did not reach V˙O2max in the 140% νV˙O2max test. Time to achieve V˙O2max was always about 50% of the time to exhaustion irrespective of the intensity. The time to exhaustion-velocity relationship was better fitted by a 3- than by a 2-parameter critical power model for running at 90%, 100%, 120%, 140% νV˙O2max as determined in the previous incremental test. In conclusion, tlimV˙O2max depended on a balance between the time to attain V˙O2max and the time to exhaustion tlim. The time to reach V˙O2max decreased as velocity increased. The tlimV˙O2max was a bi-phasic function of velocity, with a peak at 100% νV˙O2max.