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