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)over dot O-2max), (t(lim)(V)over dot O-2max). Seven physical education students ran in an incremental test (3-min stages) to determine (V)over dot O-2max and the minimal velocity at which it was elicited (v(V)over dotO(2max)). 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 t(lim) at 90%, 100%, 120% and 140% v(V)over dot O-2max 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)over dot O-2max in the 90% v(V)over dot O-2max test. All the subjects reached (V)over dot O-2max in the runs at 100% v(V)over dot O-2max. All the subjects, except one, reached (V)over dot O-2max in the runs at 120%v(V)over dot O-2max. Four subjects did not reach (V)over dot O-2max in the 140% v(V)over dot O-2max test. Time to achieve (V)over dot O-2max 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% v(V)over dot O-2max as determined in the previous incremental test. In conclusion, t(lim)(V)over dot O-2max depended on a balance between the time to attain (V)over dot O-2max and the time to exhaustion t(lim). The time to reach (V)over dot O-2max decreased as velocity increased. The t(lim)(V)over dotO(2max) Was a bi-phasic function of velocity, with a peak at 100% v(V)over dotO(2max).