It has become axiomatic that physical activity benefits the skeleton. This idea is supported by several lines of evidence, including extensive documentation of the often devastating consequences of immobilization and comparative data that show an association of increased physical activity with increased bone mass. The latter studies show that "active" or athletic subjects have significantly increased bone mineral density compared with that of sedentary controls, a difference that ranges from about 8% to 30%, almost without regard for the type of exercise.
See also pp 2197 and 2325.
Although one is tempted to conclude from these studies that activity itself increases bone mass, their cross-sectional nature leaves open the possibility of ascertainment bias. In most reports, "athletic" subjects must satisfy defined exercise inclusion criteria. A typical criterion might be to run 32 km each week for more than 5 years. Since most adults who initiate an exercise program stop training
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Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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