Wallace Lorraine Silver, Ballard Joyce E
Department of Family Medicine, The University of Tennessee Graduate School of Medicine, Knoxville 37920, USA.
J Womens Health Gend Based Med. 2002 May;11(4):389-98. doi: 10.1089/152460902317586029.
Osteoporosis is a significant public health problem associated with increased mortality and morbidity. Our aim in this cross-sectional study was to investigate the relationship between lifetime physical activity and calcium intake and bone mineral density (BMD) and BMC (bone mineral content) in 42 regularly menstruating Caucasian women (age 21.26+/-1.91 years, BMI 23.83+/-5.85).
BMD and BMC at the lumbar spine (L2-L4), hip (femoral neck, trochanter, total), and total body were assessed by dual energy x-ray absorptiometry (DXA). Lifetime history of physical activity and calcium intake was obtained by a structured interview using valid and reliable instruments.
Measures of both lifetime physical activity and calcium intake were highly correlated. In stepwise multiple regression analyses, lean mass was the most important and consistent factor for predicting BMD and BMC at all skeletal sites (attributable r2 = 28.8%-78.7%). Lifetime physical activity contributed to 3.0% of the variation in total body BMD, and life-time weight-bearing physical activity explained 15.1% of variance in lumbar spine BMC. Current calcium intake predicted 6% of the variance in BMD at the femoral neck and trochanter.
We found lean mass to be a powerful predictor of BMD and BMC in young women. Because lean mass can be modified to some extent by physical activity, public health efforts must be directed at increasing physical activity throughout the lifespan. Furthermore, our results suggest that adequate calcium intake may help to enhance bone mass, thus decreasing the risk of osteoporotic fracture later in life.
骨质疏松是一个与死亡率和发病率增加相关的重大公共卫生问题。我们在这项横断面研究中的目的是调查42名规律月经的白种女性（年龄21.26±1.91岁，体重指数23.83±5.85）一生中的身体活动、钙摄入量与骨密度（BMD）和骨矿物质含量（BMC）之间的关系。
采用双能X线吸收法（DXA）评估腰椎（L2-L4）、髋部（股骨颈、大转子、总体）和全身的BMD和BMC。通过使用有效且可靠工具的结构化访谈获取一生中的身体活动和钙摄入史。
一生中的身体活动和钙摄入量的测量结果高度相关。在逐步多元回归分析中，瘦体重是预测所有骨骼部位BMD和BMC的最重要且一致的因素（可归因的r2 = 28.8%-78.7%）。一生中的身体活动对全身BMD变化的贡献率为3.0%，一生中的负重身体活动解释了腰椎BMC变异的15.1%。当前钙摄入量预测了股骨颈和大转子处BMD变异的6%。
我们发现瘦体重是年轻女性BMD和BMC的有力预测指标。由于瘦体重可在一定程度上通过身体活动进行改变，公共卫生工作必须致力于在整个生命周期内增加身体活动。此外，我们的结果表明充足的钙摄入可能有助于增加骨量，从而降低晚年骨质疏松性骨折的风险。
