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 (VO₂(max)) in children can result in the acceptance of a 'submaximal' VO₂(max) or falsely reject a 'true' VO(₂max) and (2) the VO₂(peak) recorded during a ramp test in children is comparable to the VO₂(peak) achieved during supramaximal testing. Thirteen children (9-10 years) completed a ramp cycle test to exhaustion to determine their VO₂(peak). After 15 min of recovery, the participants performed a supramaximal cycle test to exhaustion at 105% of their ramp test peak power. Compared with the VO₂(peak) during the ramp test, a significantly lower VO₂ 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 VO₂(peak) 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). 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 VO₂(max). As supramaximal testing elicits a VO₂(peak) 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' VO₂(max) with children.
