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Stroke survivors who didn't exercise regularly when they enrolled in the prospective Health and Retirement Study had a lower likelihood of being functionally independent 3 years after their event, reported Pamela Rist, ScD, of Harvard Medical School in Boston, and colleagues.
But baseline weight status had no clear relationship with functional independence, they wrote online in Neurology.
"Those who exercised vigorously three times a week or more three years prior to stroke were more likely to be independent before and after stroke, compared to those who were inactive," Rist said in a statement. "We also found that a person's body mass index was not a factor in predicting their level of disability after stroke."
A total of 18,117 adults without a history of stroke enrolled in the cohort in 1998, and were followed for a mean of 12 years. During that time, 1,374 had a stroke and survived, and 479 died after their stroke.
Overall, baseline levels of physical activity weren't associated with stroke risk, but among those who had a stroke, being physically active at baseline was associated with a lower risk of dying after that stroke (ß= -0.110), the researchers reported.
Stroke survivors who were inactive at baseline had an 18% lower probability of being able to perform basic activities of daily living, such as getting dressed, bathing, and getting out of bed, and a 16% lower likelihood of instrumental activities of daily living, including taking medications as prescribed, food shopping, cooking meals, and managing money, they found.
However, that difference mirrored the differences in functional independence before stroke, Rist's group noted, and they observed no evidence that physical activity slowed the rate of decline in independence before or after stroke, "suggesting that being physically active does not protect against the disabling effects of a stroke itself."
Unlike the results for physical activity, there was no consistent pattern for probability of independence 3 years after a stroke when assessing patients by weight, the researchers said.
Obese patients did have a higher risk of stroke compared with normal-weight patients at baseline, but overweight patients did not.
Among stroke survivors, there were no differences between normal weight and overweight patients in rates of decline or in probability of being independent before or after stroke. Obese patients did have a lower probability of independence before their stroke, but this difference didn't persist after stroke, the researchers said.
Several retrospective studies among cohorts of stroke patients have suggested that physical activity before stroke is associated with milder strokes or better functional outcomes after stroke, and this study adds prospective evidence that physical activity is tied to post-stroke function, they said.
The study was limited by its use of self- or proxy-reported strokes and by a lack of information on stroke subtypes. Also, the measure of physical activity used was coarse and didn't assess the type or frequency of exercise in detail.
In a statement, Rist reiterated that being physically active does not seem to protect against the disabling effects of a stroke itself. "Our study was able to show that being physically inactive before stroke predicts a higher risk of being dependent both before and after stroke," she noted. "Research is needed to look into whether more intense activity could improve stroke outcomes and whether people can change their activity patterns to improve stroke outcomes."
Risk and co-authors disclosed no relevant relationships with industry.