MRC Lifecourse Epidemiology Unit, (University of Southampton), Southampton General Hospital, Southampton SO16 6YD, UK.
Osteoporos Int. 2012 Jan;23(1):121-30. doi: 10.1007/s00198-011-1641-y. Epub 2011 May 12.
In a free-living cohort of 4-year old children, mean daily time in moderate-vigorous physical activity and daily calcium intake at 3 years, were positively related to hip bone size and density. Relationships between physical activity and bone indices were stronger when calcium intake was above compared with below median (966 mg/day).
We examined the cross-sectional relationships between childhood physical activity, dietary calcium intake and bone size and density.
Children aged 4 years were recruited from the Southampton Women's Survey. They underwent measurement of bone mass by DXA (Hologic Discovery). Physical activity was assessed by accelerometry (Actiheart, Cambridge Neurotechnology Ltd, Cambridge, UK) for seven continuous days.
Four hundred twenty-two children (212 boys) participated. In a cross-sectional analysis, after adjusting for gender, daily mean time(minutes per day) spent in moderate to very vigorous activity (MVPA) was positively related to hip BA (R(2) = 3%, p < 0.001), BMC (R(2) = 4%, p < 0.001), aBMD (R (2) = 3%, p = 0.001) and estimated vBMD (R(2) = 2%, p = 0.01), but not height (r (s) = 0.04, p = 0.42) or weight (r(s) = 0.01, p = 0.76). Mean daily calcium intake (assessed at 3 years old) positively predicted bone indices in those with a calcium intake below the median (966 mg/day), but there was a much attenuated relationship in those above this. These associations persisted after inclusion of total energy, protein and phosphorus in multivariate models. The relationships between MVPA and bone indices were stronger in children with calcium intakes above the median. Thus, for aBMD, the variance explained by MVPA when daily calcium intake was below the median was 2% (p = 0.1) and above median was 6% (p = 0.001).
These results support the notion that adequate calcium intake may be required for optimal action of physical activity on bone development and that improving levels of physical activity and calcium intake in childhood may help to optimise accrual of bone mass.
在一个 4 岁的自由生活队列中，每天中等至剧烈体力活动的平均时间和 3 岁时的每日钙摄入量与髋骨大小和密度呈正相关。当钙摄入量高于（966 毫克/天）中位数时，体力活动与骨骼指数之间的关系更强。
我们研究了儿童期体力活动、膳食钙摄入量与骨骼大小和密度的横断面关系。
从南安普敦妇女调查中招募了 4 岁的儿童。他们接受了双能 X 线吸收法（DXA）（Hologic Discovery）的骨量测量。通过加速度计（剑桥神经技术有限公司，剑桥，英国的 Actiheart）连续 7 天进行体力活动评估。
422 名儿童（212 名男孩）参与了研究。在横断面分析中，在校正性别后，每天中等到非常剧烈活动（MVPA）的平均时间（分钟/天）与髋部 BA（R² = 3%，p < 0.001）、BMC（R² = 4%，p < 0.001）、aBMD（R² = 3%，p = 0.001）和估计 vBMD（R² = 2%，p = 0.01）呈正相关，但与身高（r（s）= 0.04，p = 0.42）或体重（r（s）= 0.01，p = 0.76）无关。3 岁时评估的每日平均钙摄入量（摄入量）与钙摄入量低于中位数（966 毫克/天）的儿童的骨指数呈正相关，但在摄入量高于中位数的儿童中，这种关系减弱了很多。在多变量模型中纳入总能量、蛋白质和磷后，这些关联仍然存在。在钙摄入量高于中位数的儿童中，MVPA 与骨骼指数之间的关系更强。因此，对于 aBMD，当每日钙摄入量低于中位数时，MVPA 解释的方差为 2%（p = 0.1），而中位数以上时为 6%（p = 0.001）。
这些结果支持这样一种观点，即足够的钙摄入量可能是体力活动对骨骼发育最佳作用所必需的，并且在儿童期提高体力活动和钙摄入量水平可能有助于优化骨量的积累。
