What limits endurance in normal children?
We have compared the results of a standard progressive maximal exercise test to those of an endurance exercise test in 22 healthy school children (13 girls, 9 boys, mean age 14.8 years) in order to examine whether it is possible to extrapolate results from a maximal test to predict their endurance capacity. All children performed a standard progressive maximal exercise test (15 W increments every minute until exhaustion) and an endurance test (individually calculated loads to mimic cycling at 20 km/h against a windforce 5 of Beaufort for 30 minutes) on 2 separate days. In both tests metabolic [oxygen uptake (VO2), CO2 production, blood lactate accumulation], ventilatory [minute ventilation (VE)], and circulatory variables were measured. From the maximal test the threshold of lactate accumulation (LT) was determined. Thirteen children were capable of enduring the 30 minute exercise (Group 1), and 9 could not complete the endurance test (Group 2). These two groups were comparable with respect to age, height, and baseline lung function. Children in Group 2 had a higher mean weight (P < 0.005) than those in Group 1. Eight of the 9 children in Group 2 were girls, whereas Group 1 consisted of 5 girls and 8 boys. There was no significant difference between Group 1 and 2 in the mean values of VO2 max, maximal respiratory exchange ratio (R max), VEmax, LT, oxygen pulse, and other variables obtained during the maximal exercise tests. Lactate accumulation during the endurance test in Group 2 was larger than in Group 1 (P < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
Bogaard
J M
JM
Department of Pulmonology and Pediatrics, Erasmus University, Rotterdam, The Netherlands.
Bijl
A
A
van Dongen
A R
AR
Kerrebijn
K F
KF
de Jongste
J C
JC
D000293:Adolescent; D000367:Age Factors; D001827:Body Height; D001835:Body Weight; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007773:Lactates / Q000097:blood; D008168:Lung / Q000378:metabolism / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000493:pharmacokinetics; D010807:Physical Endurance / Q000502:physiology*; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests; D013997:Time Factors
D007773:Lactates; D010100:Oxygen