Michelle N. McDonnell, PhD, from the University of South Australia in Adelaide, and colleagues compared the associations of self-reported physical activity (PA) with incident stroke among black and white participants in the Reasons for Geographic and Racial Differences in Stroke study. Analyses involved 27,348 participants aged 45 years or older without prior stroke, with follow-up every six months for stroke events. Moderate to vigorous intensity PA at baseline was classified by frequency as none (inactivity), one to three times per week, and four or more times per week.
During an average follow-up of 5.7 years, the researchers found that 33 percent of participants reported physical inactivity. Exercising at moderate to vigorous intensity (enough to break a sweat) correlated with a 20 percent reduced risk of incident stroke. The correlation was not affected by adjustment for demographic and socioeconomic factors, but was partially attenuated by adjustment for traditional stroke risk factors (diabetes, hypertension, body mass index, alcohol use, and smoking) (hazard ratio, 1.14; P = 0.17). PA frequency did not correlate significantly with the risk of stroke by sex groups, although a trend toward increased risk was observed for men reporting PA zero to three versus four or more times per week.
"Self-reported low PA frequency is associated with increased risk of incident stroke," the authors write. "Any effect of PA is likely to be mediated through reducing traditional risk factors."