Department of Medical Technology, Institute of Biomedicine, University of Oulu, Finland.
BMC Musculoskelet Disord. 2009 Nov 12;10:138. doi: 10.1186/1471-2474-10-138.
Exercise has been shown to have positive effects on bone density and strength. However, knowledge of the time-course of exercise and bone changes is scarce due to lack of methods to quantify and qualify daily physical activity in long-term. The aim was to evaluate the association between exercise intensity at 3, 6 and 12 month intervals and 12-month changes in upper femur areal bone mineral density (aBMD) and mid-femur geometry in healthy premenopausal women.
Physical activity was continuously assessed with a waist-worn accelerometer in 35 healthy women (35-40 years) participating in progressive high-impact training. To describe exercise intensity, individual average daily numbers of impacts were calculated at five acceleration levels (range 0.3-9.2 g) during time intervals of 0-3, 0-6, and 0-12 months. Proximal femur aBMD was measured with dual x-ray absorptiometry and mid-femur geometry was evaluated with quantitative computed tomography at the baseline and after 12 months. Physical activity data were correlated with yearly changes in bone density and geometry, and adjusted for confounding factors and impacts at later months of the trial using multivariate analysis.
Femoral neck aBMD changes were significantly correlated with 6 and 12 months' impact activity at high intensity levels (> 3.9 g, r being up to 0.42). Trochanteric aBMD changes were associated even with first three months of exercise exceeding 1.1 g (r = 0.39-0.59, p < 0.05). Similarly, mid-femoral cortical bone geometry changes were related to even first three months' activity (r = 0.38-0.52, p < 0.05). In multivariate analysis, 0-3 months' activity did not correlate with bone change at any site after adjusting for impacts at later months. Instead, 0-6 months' impacts were significant correlates of 12-month changes in femoral neck and trochanter aBMD, mid-femur bone circumference and cortical bone attenuation even after adjustment. No significant correlations were found at the proximal or distal tibia.
The number of high acceleration impacts during 6 months of training was positively associated with 12-month bone changes at the femoral neck, trochanter and mid-femur. These results can be utilized when designing feasible training programs to prevent bone loss in premenopausal women.
Clinical trials.gov NCT00697957.
运动已被证明对骨密度和强度有积极影响。然而，由于缺乏长期量化和定性日常体育活动的方法，人们对运动与骨变化之间的时程关系知之甚少。本研究旨在评估健康绝经前妇女在 3、6 和 12 个月的时间间隔内运动强度与 12 个月时股骨上段骨密度（aBMD）和股骨中段几何形状变化之间的关系。
35 名健康女性（35-40 岁）参与了渐进式高强度训练，研究人员使用佩戴在腰部的加速度计连续评估她们的身体活动。为了描述运动强度，在 0-3、0-6 和 0-12 个月的时间间隔内，根据五个加速度水平（范围为 0.3-9.2 g）计算个体平均每日冲击次数。在基线和 12 个月后，使用双能 X 射线吸收法测量股骨近端 aBMD，使用定量计算机断层扫描评估股骨中段几何形状。将体力活动数据与骨密度和几何形状的年变化相关联，并使用多变量分析调整试验后期月份的混杂因素和冲击影响。
股骨颈 aBMD 的变化与高强度水平（> 3.9 g）的 6 个月和 12 个月的冲击活动显著相关（r 值高达 0.42）。甚至在前三个月的运动强度超过 1.1 g 时，粗隆间 aBMD 的变化也与运动相关（r = 0.39-0.59，p < 0.05）。同样，股骨中段皮质骨几何形状的变化与前三个月的活动有关（r = 0.38-0.52，p < 0.05）。在多变量分析中，在调整后期月份的冲击影响后，0-3 个月的活动与任何部位 12 个月的骨变化均无相关性。相反，0-6 个月的冲击与股骨颈和粗隆间 aBMD、股骨中段骨周长和皮质骨衰减的 12 个月变化显著相关，即使在调整后也是如此。在近端或远端胫骨处未发现显著相关性。
在 6 个月的训练中，高加速度冲击的次数与股骨颈、粗隆和股骨中段 12 个月的骨变化呈正相关。这些结果可用于设计可行的训练方案，以预防绝经前妇女的骨丢失。
Clinicaltrials.gov NCT00697957。
