Exercise builds strong brains我们都知道体育锻炼可以强身健体。最新研究表明，体育锻炼还可以改善人的大脑机制。Kids who play hard every day may be making their brains ， as well as their bodies ， stronger.A new study reports that children who play actively for 20 to 40 minutes a day may be better able to organize schoolwork ， do class projects and learn mathematics.“Children who are not active may be at a disadvantage academically ( 在学术上 ) ，” says Catherine Davis ， a professor at the Medical College of Georgia in August.She presented the research at the annual meeting of the Obesity Society ， a group of weight loss professionals.Davis and her colleagues worked with 163 sedentary ( 惯于久坐的 ) ， overweight children ， ages 7 to 11 ， for three months.The children were divided into three groups ： a control group that did no physical activity after school ； a group that did 20 minutes of physical activity five days a week after school ； and a group that did 40 minutes of such activity on those same days.The activity groups played intermittent ( 间歇的 ) ， high energy running games.Students were given cognitive function ( 认知能力的 ) tests at the beginning and end of the study.They were tested for their math and reading achievement and “executive ( 经营管理的 ) function” ．Executive function includes skills important for planning and organizing ， focusing on schoolwork ，controlling their moods ， self monitoring and using methods to achieve goals.Among the findings from the National Institutes of Health financed study ：● The children in the 40 minute activity group had significant improvement on an executive function test compared with the control group.They increased about 4 points...
