engleski

Maximal oxygen uptake and maturation in 12-year- old male rowers

This study was designed to examine the differences in VO2max between 47 rowers of the same chronological age (12-year-olds ; mean ± SD 12, 5 ± 0, 3), but of varying levels of physical maturity. VO2max was expressed in absolute units (L/min), as the ratio standard mass-related units (mL/kg/min) and using the allometric model specific to the data set. Sexual maturity was visually assessed using indices of pubic hair developed by Tanner. The subjects were classified in pre-pubertal (Tanner stage 1), early-pubertal (Tanner stage 2), and mid-pubertal (Tanner stages 3 and 4) groups. They completed an incremental maximal treadmill test. Differences were compared using a one-way ANOVA. VO2max (L/min) in 12-year-old rowers proved to be greater in the mid-pubertal group than in both the early-pubertal (+19, 7%) and pre-pubertal (+24, 8%) groups. When expressed as a ratio standard (i.e. in mL/kg/min), VO2max was +12, 1% greater in the mid- and pre-pubertals than in the early– pubertals. However, when compared using the appropriate scaling procedure, the VO2max in mid-pubertal rowers was +14.5% greater than in the early-pubertals, and +9, 1% greater than in pre-pubertals. This suggests that factors other than body mass explain the greater aerobic power (as assessed by VO2max) in more physically mature individuals of the same chronological age. Allometric scaling of VO2max in the present study yielded a scaling coefficient for body mass of 0, 68 (95% CI = 0, 51-0, 87). This finding reinforces the view that, in children, VO2max increases relative to body mass raised to the power of 0, 67 rather than in direct proportion with body mass (i.e. mass1, 0). In conclusion, using a log-linear scaling model to adequately control for body mass, we have demonstrated significant differences in VO2max among 12-year-old rowers of varying stages of puberty and, consequently, varying levels of maturity. Further research is needed in order to further explain the above- mentioned differences among groups of rowers exhibiting differing levels of maturity independent of body mass.

VO2max ; physical maturity ; young rowers ; allometric scaling

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