Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Interactive effects of habitual physical activity and calcium intake on bone density in boys and girls
AU - Rowlands, Ann V.
AU - Ingledew, David
AU - Powell, Sarah
AU - Eston, Roger
PY - 2004/10/1
Y1 - 2004/10/1
N2 - The purpose of this study was to assess the interactive effects of habitual physical activity (total and vigorous intensity) and calcium intake on bone mineral content (BMC) in prepubertal boys and girls. Seventy-six children, aged 8–11 yr, wore accelerometers for up to 7 days to assess activity. Calcium intake was estimated by a 4-day weighted food diary. BMC and areal density (bone mineral density) were measured at the total body, proximal femur, and femoral neck by using dual-energy X-ray absorptiometry. Moderated regression analyses were used to assess the contributions of physical activity (total and vigorous) and calcium intake to BMC, residualized for bone area and body mass. Interactive effects of vigorous activity (≥6 metabolic equivalents) and calcium intake were found at the total body in boys (b = 2.90 × 10−3) and in girls (b = 6.58 × 10−3) and at the proximal femur (b = 9.87 × 10−5) and femoral neck (b = 2.29 × 10−5; where b is the regression coefficient from final equation) in boys only; residualized BMC was high only if both vigorous activity and calcium intake were high. There were no interactive effects of total activity and calcium intake. This study provides evidence for synergistic action of habitual vigorous activity and calcium intake on bone mass in children. Recommendations for optimizing bone mass should reflect this synergism.
AB - The purpose of this study was to assess the interactive effects of habitual physical activity (total and vigorous intensity) and calcium intake on bone mineral content (BMC) in prepubertal boys and girls. Seventy-six children, aged 8–11 yr, wore accelerometers for up to 7 days to assess activity. Calcium intake was estimated by a 4-day weighted food diary. BMC and areal density (bone mineral density) were measured at the total body, proximal femur, and femoral neck by using dual-energy X-ray absorptiometry. Moderated regression analyses were used to assess the contributions of physical activity (total and vigorous) and calcium intake to BMC, residualized for bone area and body mass. Interactive effects of vigorous activity (≥6 metabolic equivalents) and calcium intake were found at the total body in boys (b = 2.90 × 10−3) and in girls (b = 6.58 × 10−3) and at the proximal femur (b = 9.87 × 10−5) and femoral neck (b = 2.29 × 10−5; where b is the regression coefficient from final equation) in boys only; residualized BMC was high only if both vigorous activity and calcium intake were high. There were no interactive effects of total activity and calcium intake. This study provides evidence for synergistic action of habitual vigorous activity and calcium intake on bone mass in children. Recommendations for optimizing bone mass should reflect this synergism.
U2 - 10.1152/japplphysiol.00182.2004
DO - 10.1152/japplphysiol.00182.2004
M3 - Journal article
VL - 97
SP - 1203
EP - 1208
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 4
ER -