Abstract des Autors

The aim of the present study was to investigate the O2 uptake slow component in prepubertal children of different aerobic capacity during high intensity exercise. Twenty-three (12 well-trained, T and 11 untrained, U subjects) 10-13 year old prepubertal children took part in 3 tests: one incremental test to determine the maximal aerobic power (PMA) and anaerobic threshold (LAT); two constant-power tests performed at intensities corresponding to 80%LAT and 90%PMA. Oxygen uptake (VO2), heart rate, ventilation (VE) and lactate ([L]s) were evaluated during each test. A monoexponential+linear term model (starting after phase 1) was used to assess VO2 kinetics during both constant-power tests. Our results showed that a slow component represented by the linear coefficient (S) of the mathematical model, was present during the 90%PMA test only (S=0.86+/-0.48 ml/min/kg for the whole population). No relationships were found between either S and VE or [L]s, showing that, at least in prepubertal children, these factors play a minor role in the explanation for the VO2 slow component. The slow component contributed approximately to the same amount of the total VO2 response in both groups (T: 21.4+/-8.0, U: 19.3+/-3.9%, ns). In conclusion, as previously described in adults, our data demonstrated the existence of a slow component in prepubertal children during high-intensity exercise. Moreover, this slow component was similar in trained and untrained children, exercising at the same relative intensity. Verf.-Referat