a healthy sports( mini-essay)

Exercise Benefits Your Health（运动益身）
Moderate exercise,such as walking,can reduce the risk of diabetes in obese and sedentary people whose blood sugar is starting to rise.That outcome was shown in a large federal study in which participants were randomly assigned either to an exercise and diet program,to take a diabetes drug or to serve as controls.Despite trying hard,those who dieted and worked out lost very little weight.But they did manage to maintain a regular walking program,and fewer of them went on to develop Diabetes.
Exercise also may reduce the risk of heart disease,though the evidence is surprisingly mixed.There seems to be a threshold effect:Most of the heart protection appears to be realized by people who go from being sedentary to being moderately active,usually by walking regularly.More intense exercise has been shown to provide only slightly greater benefits.Yet the data from several large studies have not always been clear,because those who exercise tend to be very different from those who do not.