Objectives This study tested the hypotheses that (1) secondary criteria (respiratory exchange ratio (RER), heart rate, blood [lactate]) traditionally used to verify the determination of maximum oxygen uptake (V̇O_2max) in children can result in the acceptance of a ‘submaximal’ V̇O_2max or falsely reject a ‘true’ V̇O_2max and (2) the V̇O2_peak recorded during a ramp test in children is comparable to the V̇O_2peak achieved during supramaximal testing.

Methods Thirteen children (9–10 years) completed a ramp cycle test to exhaustion to determine their V̇O_2peak. After 15 min of recovery, the participants performed a supramaximal cycle test to exhaustion at 105% of their ramp test peak power.

Results Compared with the V̇O_2peak during the ramp test, a significantly lower V̇O₂ was recorded at a RER of 1.00 (1.293 litre/min (SD 0.265) vs 1.681 litre/min (SD 0.295), p<0.001, n=12), at a heart rate of 195 beats/min (1.556 litre/min (SD 0.265) vs 1.721 litre/min (SD 0.318), p<0.001, n=10) and at 85% of age-predicted maximum (1.345 litre/min (SD 0.228) vs 1.690 litre/min (SD 0.284), p<0.001, n=13). Supramaximal testing yielded a V̇O_2peak that was not significantly different from the ramp test (1.615 litre/min (SD 0.307) vs 1.690 litre/min (SD 0.284), p=0.090, respectively).

Conclusions The use of secondary criteria to verify a maximal effort in young people during ramp cycling exercise may result in the acceptance of a submaximal V̇O_2max. As supramaximal testing elicits a V̇O_2peak similar to the ramp protocol, thus satisfying the plateau criterion, the use of such tests is recommended as the appropriate method of confirming a ‘true’ V̇O_2max with children.

Keywords Children, Aerobic Fitness, Fitness Testing, Supramaximal Exercise.