Are Early or Late Maturers Likely to Be Fitter in the General Population?

The present study aims to identify the optimal body-size/shape and maturity characteristics associated with superior fitness test performances having controlled for body-size, sex, and chronological-age differences. The sample consisted of 597 Tunisian children (396 boys and 201 girls) aged 8 to 15 years. Three sprint speeds recorded at 10, 20 and 30 m; two vertical and two horizontal jump tests; a change-of-direction and a handgrip-strength tests, were assessed during physical-education classes. Allometric modelling was used to identify the benefit of being an early or late maturer. Findings showed that being tall and light is the ideal shape to be successful at most physical fitness tests, but the height-to-weight “shape” ratio seems to be test-dependent. Having controlled for body-size/shape, sex, and chronological age, the model identified maturity-offset as an additional predictor. Boys who go earlier/younger through peak-height-velocity (PHV) outperform those who go at a later/older age. However, most of the girls’ physical-fitness tests peaked at the age at PHV and decline thereafter. Girls whose age at PHV was near the middle of the age range would appear to have an advantage compared to early or late maturers. These findings have important implications for talent scouts and coaches wishing to recruit children into their sports/athletic clubs.

Questions on the Use of Vitamin D3

From their observations in a boy with hypophosphatemic rickets Chan and Bartter1 conclude that administration of 1α,25-dihydroxyvitamin D3 (1,25-(OH)2D3) is the treatment of choice for this disease. Since this point of view is not shared by everybody, it demands careful scrutiny. The conclusion rests on the increased growth velocity, the radiologic healing of the rachitic lesions, and the increase in serum phosphorus which occurred when treatment was changed from vitamin D2 to 1,25-(OH)2D3. From the growth curve of this boy it appears that the increase in growth velocity could represent the pubertal growth spurt in a late maturer.