Physical activity and rapid decline in kidney function among older adults.

Background: Habitual physical activity (PA) has both physiologic and metabolic effects that may moderate the risk of kidney function decline. We tested the hypothesis that higher levels of PA are associated with a lower risk of kidney function decline using longitudinal data from a large cohort of older adults.
Methods: We studied 4011 ambulatory participants aged 65 or older from the Cardiovascular Health Study (CHS) who completed at least 2 measurements of kidney function over 7 years. We calculated a PA score (range, 2-8) by summing kilocalories expended per week (ordinal score of 1-5 from quintiles of kilocalories per week) and walking pace (ordinal score for categories of <2, 2-3, and >3 mph). Rapid decline in kidney function decline (RDKF) was defined by loss of more than 3.0 mL/min/1.73 m(2) per year in glomerular filtration rate, which we estimated by using longitudinal measurements of cystatin C levels.
Results: A total of 958 participants had RDKF (23.9%; 4.1 events per 100 person-years). The estimated risk of RDKF was 16% in the highest PA group (score of 8) and 30% in the lowest PA group (score of 2). After multivariate adjustment, we found that the 2 highest PA groups (scores of 7-8) were associated with a 28% lower risk of RDKF (95% confidence interval, 21%-41% lower risk) than the 2 lowest PA groups (score of 2-3). Greater kilocalories of leisure-time PA and walking pace were also each associated with a lower incidence of RDKF.
Conclusion: Higher levels of PA are associated with a lower risk of RDKF among older adults.