Peripheral Bone Mineral Density and Different Intensities of Physical Activity in Children 6–8 Years Old: The Copenhagen School Child Intervention Study

Abstract

This study aimed to evaluate the association between objectively measured habitual physical activity and calcaneal and forearm bone mineral density (BMD, g/cm(2)), one mechanically more loaded and one less loaded skeletal region, in children aged 6-8 years. BMD was measured in 297 boys and 265 girls by peripheral dual-energy X-ray absorptiometry in the forearm and calcaneus. An accelerometer registered the level of physical activity during 4 days (2 weekdays and the weekend). Weight, height, and skinfold thickness were measured. In order to establish thresholds (count . min(-1)) for bone-stimulating physical activity, we evaluated different definitions of vigorous physical activity. The boys had 3.2% higher distal forearm bone mineral content (BMC, P < 0.001) and 4.5% higher distal forearm BMD (P < 0.001) than the girls. They also carried out 9.7% more daily physical activity and spent 14.6-19.0% more time in vigorous physical activity (all P < 0.05) compared to the girls. In contrast, the girls had 3.8% higher calcaneal BMC (P < 0.01) and 2.5% higher calcaneal BMD (P < 0.05) than the boys. Both calcaneal and forearm BMD were significantly related to total time of daily physical activity as well as with intense physical activity above all the chosen cut-off points (all P < 0.05). The beta value for mean count . min(-1) physical activity was significantly lower than that for all the chosen cut-off points of vigorous activity both for calcaneal and distal forearm BMD. This study suggests that both habitual daily physical activity and amount of vigorous physical activity in children aged 6-8 years are associated with appendicular BMD.

Ward's area location, physical activity, and body composition in 8- and 9-year-old boys and girls

“…(28,29) Physical activity and body composition are important determinants of bone mass, geometry, and strength of the femoral neck. (30)(31)(32)(33)(34) It is reasonable to assume that mechanisms connecting physical activity and body composition to bone mass are also linked to structural adaptation, that is, redistribution of bone mass. As a weight-bearing bone, the femur is particularly stimulated during locomotion movements that affect different diverse areas of the bone.…”

Association between intake of dietary protein and 3-year-change in body growth among normal and overweight 6-year-old boys and girls (CoSCIS)

“…All measurements were carried out using standardised methods, which have been described in detail elsewhere (23,24) . Height was measured by a Harpenden stadiometer, to the nearest 1 mm.…”

“…The children were instructed to wear the monitor continuously except during waterbased activities or when sleeping. A mean count was calculated for each child (24) . The classification of SES was based on information regarding the education of the mother in the household at the first measurement point, as recent studies suggest that the risk factors considered herein are more strongly associated with the SES of the mother rather than that of the father (29)(30)(31) .…”

Relação entre atividade física e densidade mineral óssea/osteoporose: uma revisão da literatura nacional

“…A prática de atividade física ao longo de diferentes fases da vida tem sido sugerida como fator de proteção de osteoporose (HASSELSTROM et al, 2007;MIYABARA et al, 2007;NILSSON et al, 2008). De fato, alguns estudos epidemiológicos transversais (HASSELSTROM et al, 2007;MIYABARA et al, 2007;NILSSON et al, 2008) analisando a influência da prática de atividade física na infância ou na idade adulta têm sugerido que os indivíduos mais ativos fisicamente são aqueles que apresentam maior DMO.…”

“…De fato, alguns estudos epidemiológicos transversais (HASSELSTROM et al, 2007;MIYABARA et al, 2007;NILSSON et al, 2008) analisando a influência da prática de atividade física na infância ou na idade adulta têm sugerido que os indivíduos mais ativos fisicamente são aqueles que apresentam maior DMO. Esses achados também vêm sendo corroborados por estudos longitudinais que verificaram efeitos positivos do treinamento físico da DMO de humanos e modelos experimentais (JUDGE et al, 2005;KATO et al, 2006).…”