Gas exchange response to exercise in children.

We measured the gas exchange response to exercise in 109 normal children (51 girls and 58 boys, ranging in age from 6 to 17 yr old) using noninvasive breath-by-breath techniques. The protocol consisted of cycle ergometry in which the work rate increased in a linear manner (ramp forcing function) until the limit of the subject's tolerance was reached. We measured the maximal oxygen uptake (VO2max) and the VO2 at the anaerobic threshold (AT). We found that both of these parameters were highly correlated with increasing height, and that for both the AT and VO2max, the values for boys were significantly higher than girls. We compared our results of VO2max to those obtained by Astrand over 30 years ago using different techniques. When boys and girls were considered together, there were no significant differences between our study and Astrand's; however, girls in our study had significantly lower values for VO2max than did girls in Astrand's study. These data provide normal values for both VO2max and AT and can be used to evaluate the exercise impairment resulting from disease in children.