Adults should aim to get in 2 1/2 hours of exercise a week and children should run and play for at least an hour a day, according to new exercise guidelines issued by the US government on Tuesday.

The guidelines, meant to be akin to the "Food Pyramid" nutritional advice, are based on studies that show clear health benefits from regular, moderate exercise.

"More than 59 percent of adults don't get enough physical activity and a quarter of adults aren't active at all in their leisure time," Health and Human Services Secretary Michael Leavitt said in a telephone interview.

"I think these are the first comprehensive federal guidelines on physical activity."

Many studies have shown that regular moderate exercise lowers the risk of heart disease, many cancers, osteoporosis, diabetes, Alzheimer's disease, depression and other diseases.

"In children and adolescents, physical activity induces cardiovascular and respiratory fitness and also contributes to bone health," Leavitt said.

The latest figures released in July from the US Centers for Disease Control and Prevention show 25.6 percent of U.S. adults are medically obese. Both poor diet and a lack of exercise are blamed.

In 2002, the U.S. Institute of Medicine said Americans need to exercise at least one full hour a day to maintain weight and health.

The new HHS guidelines go a bit easier and recommend an average of half an hour a day, five days a week -- or more.

People should get exercise any way they can, said Melissa Johnson, executive director of the President's Council on Physical Fitness and Sports. "Brisk walking is a phenomenal example," she said.

Children need 60 minutes a day of physical activity, said Rear Adm. Penelope Royall, deputy assistant secretary for health. "We want to encourage muscle-strengthening activity as well," Royall said in the telephone interview.

美国政府于本周二发布了一份最新“锻炼指南”。该指南建议，成年人每周应锻炼两个半小时，儿童每天应至少活动一小时。

这份指南与之前的《食物金字塔》指南类似，是根据大量研究编撰的。此前很多研究表明，定期的、适度的锻炼能给健康带来明显益处。

美国卫生及公共服务部部长迈克尔?里维特在一次电话采访中说：“超过95%的成年人缺乏锻炼，四分之一的人在业余时间完全不锻炼。”

“这是首个全国性的有关身体锻炼的综合指南。”

很多研究表明，经常进行适度锻炼能够降低患心脏病、多种癌症、骨质疏松、糖尿病、老年痴呆和抑郁症等疾病的风险。

里维特称：“儿童和青少年进行体育锻炼则能够促进心血管和呼吸道健康，而且有益于骨骼健康。”

美国疾病防控中心今年7月发布的最新统计数据显示，美国25.6%的成年人患有肥胖症。而导致这一问题的罪魁祸首就是垃圾食品和缺乏锻炼。

美国医学院于2002年指出，美国人每天至少要锻炼一小时，才能控制体重和保持健康。

而美国卫生及公共服务部发布的这份健康指南则相对要容易一点，根据建议，每天锻炼半小时，一周坚持五天或更多就能达到这一目标。

保健与运动总统顾问办公室主任玛丽萨?约翰逊说，无论何种锻炼方式都可以，快步走就是一个突出的例子。

卫生部副部长佩内洛普?罗约尔少将在电话采访中说：“儿童每天需要活动一个小时。此外，我们建议孩子们进行一些加强肌肉的锻炼。”