BIO-ENERGETIC PROFILE IN 144 BOYS AGED FROM 6 TO 15 YEARS WITH SPECIAL REFERENCE TO SEXUAL-MATURATION

The effects of growth and pubertal development on bio-energetic characteristics were studied in boys aged 6-15 years (n = 144; transverse study). Maximal oxygen consumption (VO2max, direct method), mechanical power at VO2max (P(VO2max)), maximal anaerobic power (P(max); force-velocity test), mean power in 30-s sprint (PBAR30s; Wingate test) were evaluated and the ratios between P(max), P30s and P(VO2max)) were calculated. Sexual maturation was determined using salivary testosterone as an objective indicator. Normalized for body mass VO2max remained constant from 6 to 15 years (49 ml.min-1.kg-1, SD 6), whilst P(max) and PBAR30s increased from 6-8 to 14-15 years, from 6.2 W.kg-1, SD 1.1 to 10.8 W.kg-1, SD 1.4 and from 4.7 W.kg-1, SD 1.0 to 7.6 W.kg-1, SD 1.0, respectively, (P < 0.001). The ratio P(max):P(VO2max) was 1.7 SD 3.0 at 6-8 years and reached 2.8 SD 0.5 at 14-15 years and the ratio PBAR30s:P(VO2max) changed similarly from 1.3 SD 0.3 to 1.9 SD 0.3. In contrast, the ratio P(max):PBAR30s remained unchanged (1.4 SD 0.2). Significant relationships (P < 0.001) were observed between P(max) (W.kg-1), PBAR30s (W.kg-1), blood lactate concentrations after the Wingate test, and age, height, mass and salivary testosterone concentration. This indicates that growth and maturation have together an important role in the development of anaerobic metabolism.