PHYSICAL-ACTIVITY AND STROKE RISK - THE FRAMINGHAM-STUDY

The authors prospectively examined the influence of increased levels o f physical activity on risk of stroke in members of the Framingham Stu dy cohort. Two separate analysis were performed, one during midlife in 1,897 men (mean age = 49.7 years) and 2,299 women (mean age = 49.9 ye ars) and another when the cohort was older (1,361 men (mean age = 63.0 and 1,862 women (mean age = 63.7)). A structured questionnaire admini stered two separate examinations was used to estimate the amount of me tabolic work done during a typical 24-hour period. Physical activity w as categorized into tertiles, and medium and high levels of physical a ctivity were compared with a low level of physical activity, which was used as the referent group. Cox proportional hazards, life table, and time-dependent covariate analysis were used to examine the relation b etween level of physical activity and stroke risk over a follow-up per iod of 32 years. In men, adjusted analyses revealed that increased lev els of physical activity were protective. The strongest effect was obt ained from an analysis involving older cohort members in the medium te rtile (risk ratio = 0.41, 95% confidence interval 0.24-0.69). High lev els of physical activity did not confer an additional benefit over med ium levels. Adjusted analysis showed no significant protective effect in women. These results indicate that medium and high levels of physic al activity among men are protective against stroke relative to low le vels.