The effect of different treadmill speeds on the variability of VO2 max in children.

Eight boys aged 10-12 years performed three tests on each of three treadmill protocols. Each test was a continuous, progressively graded performance to exhaustion, but protocols differed in speed--(walk: 90 m . min-1, jog: 110 m . min-1, run: 130 m . min-1). The walk protocol was found inappropriate for VO2 max determination in children. Compared to the faster speeds, the walk test elicited a lower VO2 at exhaustion, and had lower reliability (0.56) and a high coefficient of variation (8%). For the Vo2 at exhaustion on the jog and run protocols the coefficient of variation was 3-5% and the reliability coefficient averaged 0.90, comparable to values seen for repeated trials in adults. The usually accepted VO2 max criterion of a plateau of VO2 with increasing work levels was inappropriate for use with children. Attempts to derive plateau criteria suitable for use with children proved unsuccessful. Plateau criteria may be difficult to achieve with children in light of their apparently weaker glycolytic energy capacity. Nevertheless, the highest VO2 measured at jog or run speeds has a consistency similar to that found for Vo2 max measurement in adults.