High-Intensity Exercise May Reduce Cardiovascular Risk CME
News Author: Laurie Barclay, MD
CME Author: Bernard M. Sklar, MD, MS
Authors and Disclosures
Release Date: April 18, 2003; Valid for credit through April 18, 2004
April 18, 2003 ? Only high intensity exercise is related to reduced risk of cardiovascular disease, according to the results of a prospective study published in the May issue of Heart. Low- or moderate-intensity regular exercise did not appear to exert a protective effect.
“Many studies have shown that physical activity during leisure is associated with a decrease in all cause mortality and may extend life by 1-2 years,” write S. Yu and colleagues from Queens’ University Belfast in Northern Ireland. “But the optimal intensity of leisure time physical activity is still unclear.”
Current U.K. and U.S. guidelines for cardiovascular health recommend 30 minutes of moderately intense physical activity, such as brisk walking, on at least five days weekly, to reduce cardiovascular risk and premature death.
In this prospective study based on a population sample of 1,975 men in Caerphilly, Wales, who were aged between 45 and 59 years when first enrolled, none had evidence of heart disease at baseline. Subjects completed detailed questionnaires on medical history, usual levels of leisure and occupational physical activity, diet, smoking, and other lifestyle factors.
Leisure exercise was graded according to intensity, with light activities defined as walking, bowling, or sailing; moderate activities as golf, digging, and dancing; and heavy activities as climbing stairs, swimming, and jogging. Approximately 40% admitted to no or very little vigorous exercise.
During a mean follow-up of 10.5 years, 252 men (13%) died. Cause of death was cardiovascular disease in 111 (44%), coronary heart disease in 82 (33%), and cancer in 98 (39%). Excluding deaths from cancer, men in the least active group had the highest premature death rates.
After adjusting for age and other confounding factors, the heaviest levels of physical activity were associated with the lowest rates of death from all causes and from heart disease. Moderate and light levels of regular exercise had no consistent impact on all-cause or cardiovascular mortality. Intensity of exercise, rather than the amount of energy expended, appeared to protect against cardiovascular death.
In the 20% of men who regularly engaged in heavy exercise, but whose daily energy expenditure was only 54 Kcals, risk of premature death was decreased by 47%, and risk of cardiovascular death was decreased by 62%. Men with daily energy expenditure between 16 and 53 Kcals were 16% less likely to die prematurely and 27% less likely to die of cardiovascular disease.
Energy expenditure of 54 Kcals daily is approximately equivalent to nine minutes of jogging or doubles tennis, or to seven minutes of climbing stairs.
Men who took part in light to moderate exercise, with an average energy expenditure of 343 Kcals a day, equivalent to over 90 minutes of leisurely walking or an hour of ballroom dancing, did not have reduced risk of premature death.
Study limitations include collection of data on physical activity only at baseline, potential sources of bias, and use of a self-rated questionnaire to assess physical activity.
“Vigorous physical activity, such as climbing stairs, hiking, jogging, swimming, tennis, badminton, squash, may independently prevent premature death, principally from cardiovascular disease and coronary heart disease, in middle-aged men who have no evidence of pre-existing coronary heart disease,” the authors write.