Heart Benefits Of Exercise Based On Perception

Regular exercise can help prevent heart disease, but how much exercise does it take?

Harvard researchers found that the intensity of physical activity needed to reduce the risk of heart disease depends on individual fitness levels. Their findings are published in Monday's rapid access issue of Circulation: Journal of the American Heart Association.

Lead researcher Dr. I-Min Lee said that perception is key.

"The harder one exercises, based on his or her perception, the lower the risk of heart disease, even if the activity does not meet current recommendations for physical activity," Lee said.

Exercise recommendations are usually given in absolute terms, referring to the actual rate of energy expended, which is often expressed in metabolic equivalents, known as METs.

Lee emphasized that everyone should be physically active.

"Don't worry about whether your exertion level corresponds to current recommendations. If you persist at your own rate and become more physically fit, you should then ratchet up your intensity to continue to receive health benefits," she said.

Vigorous exercise like jogging, for example, requires more than six METs, and brisk walking requires three or more. Current guidelines from the Centers for Disease Control and Prevention and the American College of Sports Medicine recommend expending three to six METs, or three to six times the resting metabolic rate, the researchers said.

Lee and her colleagues said using a relative scale to gauge the intensity of activity may be more appropriate than the absolute scale. The absolute scale is based on the fitness of healthy, younger adults. But the researchers said it would be important to consider how relative intensity for a certain activity changes with age and in less physically fit people.

"Brisk walking, at 3 to 4 mph, would not require much effort for a young, physically fit man, relative to his fitness because he is highly fit," Lee said. "He might perceive this as 'light' exercise. However, for an old, unfit woman, the same level of activity might require almost all of her energy. She might perceive this as 'very vigorous' exercise."

The researchers used data from men in the Harvard Alumni Health Study. For this report, the researchers followed 7,337 men, with an average age 66, who periodically filled out questionnaires describing lifestyle habits from 1988 to 1995.

The researchers found that the risk of heart disease among men who rated their exercise exertion as "moderate" was 14 percent lower than those who rated their exercise as "weak" or less intense.

Men who perceived their intensity as "somewhat strong" had a 31 percent lower risk, and those ranking their level as "strong" or more intense had a 28 percent lower rate. The researchers said the heart benefits extended to men who were not reaching current recommendations.

But that doesn't mean current exercise requirements should be ignored, the researchers said.

In fact, data from the study supports the recommendations, showing that men who expended more than 1,000 calories per week or who exercised at vigorous absolute intensity had lower heart disease rates compared to those who did not.