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.

美國政府于本周二發布了一份最新“鍛煉指南”。該指南建議，成年人每周應鍛煉兩個半小時，兒童每天應至少活動一小時。

這份指南與之前的《食物金字塔》指南類似，是根據大量研究編撰的。此前很多研究表明，定期的、適度的鍛煉能給健康帶來明顯益處。

美國衛生及公共服務部部長邁克爾•里維特在一次電話采訪中說：“超過95%的成年人缺乏鍛煉，四分之一的人在業余時間完全不鍛煉。”

“這是首個全國性的有關身體鍛煉的綜合指南。”

很多研究表明，經常進行適度鍛煉能夠降低患心臟病、多種癌癥、骨質疏松、糖尿病、老年癡呆和抑郁癥等疾病的風險。

里維特稱：“兒童和青少年進行體育鍛煉則能夠促進心血管和呼吸道健康，而且有益于骨骼健康。”

美國疾病防控中心今年7月發布的最新統計數據顯示，美國25.6%的成年人患有肥胖癥。而導致這一問題的罪魁禍首就是垃圾食品和缺乏鍛煉。

美國醫學院于2002年指出，美國人每天至少要鍛煉一小時，才能控制體重和保持健康。

而美國衛生及公共服務部發布的這份健康指南則相對要容易一點，根據建議，每天鍛煉半小時，一周堅持五天或更多就能達到這一目標。

保健與運動總統顧問辦公室主任瑪麗薩•約翰遜說，無論何種鍛煉方式都可以，快步走就是一個突出的例子。

衛生部副部長佩內洛普•羅約爾少將在電話采訪中說：“兒童每天需要活動一個小時。此外，我們建議孩子們進行一些加強肌肉的鍛煉。”