The Slow Component of O₂ Uptake Kinetics During High-Intensity Exercise in Trained and Untrained Prepubertal Children

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 (V˙O₂), heart rate, ventilation (V˙E) and lactate ([L]s) were evaluated during each test. A monoexponential + linear term model (starting after phase 1) was used to assess V˙O₂ 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^-2 × kg^-1 for the whole population). No relationships were found between either S and V˙E or [L]s, showing that, at least in prepubertal children, these factors play a minor role in the explanation for the V˙O₂ slow component. The slow component contributed approximately to the same amount of the total V˙O₂ 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.

Key words:

O₂ uptake kinetics - pulmonary gas exchange - children - training

References

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