Bio-energetic profile in 144 boys aged from 6 to 15 years with special reference to sexual maturation

Summary

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 (VO_2max, direct method), mechanical power at (VO_2max (${\text{P}}_{\dot V{\text{O}}_{{\text{2max}}} }$), maximal anaerobic power (P_max; force-velocity test), mean power in 30-s sprint (P _30s; Wingate test) were evaluated and the ratios between P_max,P _30s and${\text{P}}_{\dot V{\text{O}}_{{\text{2max}}} }$ were calculated. Sexual maturation was determined using salivary testosterone as an objective indicator. Normalized for body massVO_2max remained constant from 6 to 15 years (49 ml· min⁻¹ · kg⁻¹, SD 6), whilst P_max andP _30s 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:${\text{P}}_{\dot V{\text{O}}_{{\text{2max}}} }$ was 1.7 SD 3.0 at 6–8 years and reached 2.8 SD 0.5 at 14–15 years and the ratioP _30s:${\text{P}}_{\dot V{\text{O}}_{{\text{2max}}} }$ changed similarly from 1.3 SD 0.3 to 1.9 SD 0.3. In contrast, the ratio P_max:P _30s remained unchanged (1.4 SD 0.2). Significant relationships (P < 0.001) were observed between P_max (W · kg⁻¹),P _30s (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.