Sports Med Experts Say
30-Min Exercise Rule Sticks
Excerpt By Charnicia E. Huggins, Reuter's Health

NEW YORK (Reuters Health) - The new recommendation by the Institute of hedicine's (IOM) Food and Nutrition Board that Americans exercise for an hour every day may be confusing and disheartening to people who thought 30 minutes of exercise on most days of the week was good enough, according to experts from the American College of Sports Medicine.

"By raising the recommendation to 60 minutes of moderate physical activity per day, the report has the potential to dissuade the most sedentary from initiating a pattern of moderate physical activity that would be a healthy lifestyle change and could lead to additional increases in total physical activity," Dr. Edward T. Howley, ACSM's president, said in a statement.

The IOM released its latest set of recommendations on diet and physical activity earlier this month. In addition to advising that Americans reduce their caloric intake and try to eliminate saturated fats and added sugars from their diet, the panel also said that people should exercise for 60 minutes each day to maintain maximum cardiovascular health and prevent weight gain.

Yet, in making their blanket 60-minute recommendation--double that of the 1996 US Surgeon General's recommendation of 30 minutes of exercise on most days of the week--the panel failed to address individual variation in health and weight benefits from exercise, ACSM experts said on Wednesday during a telephone media briefing.

"Even for the limited objective of preventing unhealthy weight gain, clearly there are some people who never exercise and never gain weight," said Dr. Steven Blair, scientific editor of the Surgeon General's 1996 Report on Physical Activity and Health. "Clearly there must be individual variation (and) genetic factors that require some people to get more (exercise) than others."

Further, the IOM report states that 30 minutes of activity may not be enough to maintain a healthy weight and benefit from all the purported health effects of exercise. Blair agrees that a half-hour of regular exercise may not give exercisers "maximal" health benefits, but he added that it is not known how much exercise is required for "maximal" benefit.

In fact, there is little evidence that 60 minutes--or any other amount of time--spent in moderate exercise can provide individuals with maximum health benefits, according to Blair. Meanwhile, the evidence backing the 30-minute recommendation is "very strong, and getting stronger every day," he said.

As it stands, exercising for 30 minutes on most days of the week--whether in one half-hour block or three 10-minute spurts--is known to lower a person's risk of heart disease, stroke and hypertension as well as prevent diabetes and delay death from any cause, Blair said.

As for determining how much exercise is needed to prevent weight gain, there are two easy ways to find out, Blair said: "belts and bathroom scales."

Reference Source 89

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