Skeletal growth: A major determinant of bone's structural diversity in women and men

Skeletal fragility in advanced age has its antecedence in growth because the variance in bone traits achieved during growth is an order of magnitude greater than rates of loss during aging. Factors modifying skeletal morphology such as exercise and nutrition are likely to be best during growth. At puberty, appendicular growth decelerates while axial growth accelerates. Sex differences in bone length, width, mass, and strength emerge largely during puberty. In late puberty, there is slowing of longitudinal bone growth. The effects of illness during growth depend on the maturational stage at the time of disease exposure, not just the “severity” of the illness. In particular, growth of the distal radius is more rapid at the distal metaphysis, and at this site the longitudinal growth outpaces bone formation upon the surfaces of trabeculae emerging from the growth plate, delaying their coalescence

Weight-bearing bones are more sensitive to physical exercise in boys than in girls during pre- and early puberty: a cross-sectional study.

We carried out a cross-section study of the sex-specific relationship between bone mineral content and physical activity at sites with different loading in pre- and early pubertal girls and boys. There was significant sensitivity of bone mineral content of the hip to physical exercise in boys, but not in girls. BACKGROUND: Since little is known whether there are sex differences in sensitivity of bone to loading, we investigated sex differences in the cross-sectional association between measures of physical activity (PA) and bone mass and size in pre- and early pubertal children of both sexes. METHODS: We measured bone mineral content/density (BMC/BMD) and fat-free mass (FFM) in 269 6- to 13-year-old children from randomly selected schools by dual-energy X-ray absorptiometry. Physical activity (PA) was measured by accelerometers and lower extremity strength by a jump-and-reach test. RESULTS: Boys (n = 128) had higher hip and total body BMC and BMD, higher FFM, higher muscle strength and were more physically active than girls (n = 141). Total hip BMC was positively associated with time spent in total and vigorous PA in boys (r = 0.20-0.33, p < 0.01), but not in girls (r = 0.02-0.04, p = ns), even after adjusting for FFM and strength. While boys and girls in the lowest tertile of vigorous PA (22 min/day) did not differ in hip BMC (15.62 vs 15.52 g), boys in the highest tertile (72 min/day) had significantly higher values than the corresponding girls (16.84 vs 15.71 g, p < 0.05). CONCLUSIONS: Sex differences in BMC during pre- and early puberty may be related to a different sensitivity of bone to physical loading, irrespective of muscle mass