Aerobic capacity of competitive ice hockey players 10-15 years old.

Oxygen uptakes (V-O2) recorded at anaerobic threshold and at the end of a maximal exercise (V-O2max) and their relation to left ventricular function were analyzed in 11 young ice hockey players during an incremental exercise on a bicycle ergometer. The children, highly trained, participated annually during 6 years (from the age of 10-15 years) in laboratory tests. The maturative status of the subjects was evaluated from peak height velocity (PHV). Heart rate was recorded by electrocardiogram. Oxygen uptake, CO2 production, respiratory frequency, pulmonary ventilation (V-E) were recorded at rest and every 30s during exercise through a Rudolph valve connected to a calibrated oxycon gas analyser. The anaerobic threshold was determined by a non-invasive method from pulmonary ventilation curves. Left ventricular volumes at end-systole and end-diastole were obtained, at rest, by M mode echocardiography. Results showed that both V-O2 at anaerobic threshold and V-O2max were positively correlated with body mass or with age of PHV. The increments were constant from year to year. At anaerobic threshold, the ratio V-O2/V-O2max was independent of maturative age. Similar findings were observed when considering V-E except after the years of PHV where there was a remarkable increase in pulmonary ventilation. The results indicate that the growth of each cardiorespiratory component is optimalized with body size increase in order to keep constant the aerobic response to exercise. As judged by the explained variance of the different linear regression analyses between resting left ventricular dimensions and V-O2, cardiac volume was of minimal importance in determining V-O2. In the postpubertal period, stroke volume accounted for 26.7% of V-O2, at anaerobic threshold and 30.0% of V-O2max. This suggests that local changes occurring at muscular level are of paramount importance in determining the aerobic capacity of highly trained boys.