Physical Activity and Risk of Stroke
Methods: The Northern Manhattan Study is a prospective cohort study in older, urban-dwelling, multiethnic, stroke-free individuals. Baseline measures of leisure-time physical activity were collected via in-person questionnaires. Cox proportional hazards models were constructed to examine whether energy expended and intensity of physical activity were associated with the risk of incident ischemic stroke.
Results: Physical inactivity was present in 40.5% of the cohort. Over a median follow-up of 9.1 years, there were 238 incident ischemic strokes. Moderate- to heavy-intensity physical activity was associated with a lower risk of ischemic stroke (adjusted hazard ratio [HR] 0.65, 95% confidence interval [0.44–0.98]). Engaging in any physical activity vs none (adjusted HR 1.16, 95% CI 0.88–1.51) and energy expended in kcal/wk (adjusted HR per 500-unit increase 1.01, 95% CI 0.99–1.03) were not associated with ischemic stroke risk. There was an interaction of sex with intensity of physical activity (p = 0.04), such that moderate to heavy activity was protective against ischemic stroke in men (adjusted HR 0.37, 95% CI 0.18–0.78), but not in women (adjusted HR 0.92, 95% CI 0.57–1.50).
Conclusions: Moderate- to heavy-intensity physical activity, but not energy expended, is protective against risk of ischemic stroke independent of other stroke risk factors in men in our cohort. Engaging in moderate to heavy physical activities may be an important component of primary prevention strategies aimed at reducing stroke risk.
From press release:
Men who regularly take part in moderate-to-heavy intensity exercise such as jogging, tennis or swimming may be less likely to have a stroke than people who get no exercise or only light exercise, such as walking, golfing, or bowling, according to a study published in the November 24, 2009, print issue of Neurology®, the medical journal of the American Academy of Neurology.
However, exercise did not have a protective effect against stroke for women. Women who took part in moderate-to-heavy intensity exercise did not have a reduced risk of stroke.
The study involved 3,298 people living in northern Manhattan, NY, with an average age of 69 who were followed for about nine years. During that time, there were 238 strokes. A total of 41 percent of the participants reported that they participated in no physical activity. Twenty percent regularly participated in moderate-to-heavy intensity activities.
Men who participated in moderate-to-heavy intensity activities were 63 percent less likely to have a stroke than people with no physical activity. The baseline risk of ischemic stroke over five years in the entire group was 4.3 percent; among those with moderate-to-heavy intensity activities the risk was 2.7 percent, and among those with no activity it was 4.6 percent.
"Taking part in moderate-to-heavy intensity physical activity may be an important factor in preventing stroke," said study author Joshua Z. Willey, MD, of Columbia University Medical Center and New York Presbyterian Hospital at Columbia. Willey is also a member of the American Academy of Neurology. "A large percentage of the participants were not taking part in any physical activities. This may be true of many elderly people who live in cities. Identifying ways to improve physical activity among these people may be a key goal for public health."
These results are contrary to some other studies that found that even light intensity physical activity reduced the risk of stroke. Willey said the number of participants may not have been large enough to detect subtle differences in the group that took part in only light physical activity.
Stroke is the leading cause of disability and the third-leading cause of death in the United States.
J. Z. Willey, Y. P. Moon, M. C. Paik, B. Boden-Albala, R. L. Sacco, and M.S.V. Elkind
Physical activity and risk of ischemic stroke in the Northern Manhattan Study
Columbia University, New York.