Twenty athetic and 20 non-athletic male college students aged 19-24yr were employed to exercise on a treadmill using 4 speeds(4.02, 5.47, 6.76 and 8.05km/h) and 5 grades(0, 8, 12, 16 and 20%). A fixed speed was selected for each session with the grade increased every 3 min. The Vo₂, heart rate, stride frequency and stride length were measured during the last min of each 3-min stage.

Vo₂increased linearly with increasing speed and grade showing significant multiple correlations in nonathletes(Vo₂=3.64x+0.831y+0.031xy-7.03, R=0.98, P<0.01) and athletes(Vo₂=3.48x+0.324y+0.112xy-5.74, R=0.99, P<0.01). Stride frequency and length tended to increase with increasing speed except for the transition from walking to runnig at 8.05Km/h at which the stride frequency ran up much higher with the stride length getting lower than at 6.76Km/h. Heart rate increased linearly with increasing Vo₂. The rate of increase was higher during walking than during running.

These results indicate that athletes have higher rate of increase in Vo₂than nonathletes at near-maximal exercise and may be used as a guideline in predicting maximum oxygen comsumption and in prescribing exercise intensity.