UPDATE: Want to make a great New Year's resolution? There is evidence that more than 250,000 deaths each year can be attributed to physical inactivity. There is also evidence that moderate activity can lower your risk almost as much as vigorous exercise. The December issue of the Nutrition Action Health Letter contained interviews with seven leading researchers in the area of physical activity. I'd like to summarize some of the questions and answers in today's column to help convince any of you who are non-exercisers to take the step in 1994.

Question: Do you have to jog or run to benefit from exercise?

Answer: No. Doing anything is better than nothing, because those who are moderately active have much lower death rates than people who are inactive.

Question: How much exercise is enough?

Answer: People should accumulate 30 minutes or so of moderate-intensity activity, such as walking, on most days. You don't have to go out for a 30-minute walk. You can take three 10-minute walks and get more or less comparable results.

Question: Is vigorous exercise sustained for 20 to 30 minutes critical?

Answer: No. Recent research shows that regular, moderate activity can substantially cut your risk of disease. The key thing is to get up and get moving and not worry about intensity. It's the total energy spent in physical activity that's most important. You can spend 300 calories by running three miles in half an hour, or you can spend it in six 10-minute walks throughout the day. The benefits may not be exactly the same but they're comparable.

Question: How does exercise protect the heart?

Answer: A moderate amount of exercise increases HDL (the "good" cholesterol). It also lowers blood pressure, makes you less likely to gain weight, increases insulin sensitivity in the muscles and lowers the risk of forming blood clots.

Question: Can exercise help prevent cancer?

Answer: There is consistent, strong epidemiological evidence that exercise is associated with a lower rate of colon cancer in humans. Of course, this kind of research cannot prove cause-and-effect. But it does suggest that exercise may provide the same degree of protection against colon cancer that you find between exercise and heart disease.

Question: What about cancers other than colon cancer?

Answer: In animals, exercise protects against breast tumors. Exercise may reduce the amount of estrogen available to promote breast tumors, or it may stimulate the immune system to attack growing cancers.

Question: Does exercise strengthen bones?

Answer: Yes, but women who want to really build up their bones have to dedicate themselves to extended periods of serious exercise. The sad thing is that bones lose the extra minerals if exercise is stopped.

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Question: Then why bother?

Answer: Because bone is lost very rapidly through inactivity. You don't have to build up a lot of bone, but you certainly don't want to lose any. That's why women are encouraged to pick a moderate weight-bearing exercise that they really enjoy, such as walking, and do it for a lifetime.

Next week I will conclude these questions and answers.

Garth Fisher is director of the Human Performance Research Center at Brigham Young University.

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