Exercise may boost kidney function in sedentary older adults

Patients randomized to a physical activity and exercise intervention had statistically significantly lower decline in estimated glomerular filtration rate over two years versus those who received health education, a recent analysis found.

Compared with health education, a physical activity and exercise intervention slowed the rate of decline in kidney function among community-dwelling sedentary older adults, a recent study found.

An ancillary analysis of the Lifestyle Interventions and Independence For Elders randomized clinical trial included 1,199 community-dwelling adults ages 70 to 89 years who were sedentary (defined by reporting <20 min/d of regular physical activity and <125 min/wk of moderate physical activity) and had mobility limitations and available blood specimens. The original trial was conducted across eight academic centers from February 2010 through December 2013. Data for the current study were analyzed from March 29, 2021, to February 28, 2022.

The exercise arm was a structured, two-year, partially supervised, moderate-intensity physical activity and exercise intervention compared with a health education control intervention with two years of follow-up. The exercise intervention targeted both strength and flexibility. Physical activity was measured by step count and minutes of moderate-intensity activity using accelerometers. The study results were published May 2 by JAMA Internal Medicine.

The primary outcome was change in estimated glomerular filtration rate (eGFR) per cystatin C. Rapid decline in eGFR was defined by the high tertile threshold of 6.7% per year. The mean decline in eGFR was 1.42 mL/min/1.73 m2 at year one of follow-up and 2.99 mL/min/1.73 m2 at year two. Participants in the intervention arm had a slower rate of kidney function decline (mean difference, 0.96 [95% CI, 0.02 to 1.91] mL/min/1.73 m2) on average during the two-year follow-up period and lower odds of rapid decline in eGFR (odds ratio, 0.79; 95% CI, 0.65 to 0.97). Subgroup analysis showed that participants in the higher eGFR stratum appeared to derive greater benefit from exercise.

Overall, at year two, 302 (29.1%) participants had rapidly declining kidney function, including 135 (25.9%) in the physical activity arm and 167 (32.2%) in the health education control group. Randomization to the physical activity arm statistically significantly lowered the odds of rapid kidney function decline by approximately 20% over the two years. The intervention's effect on rapid kidney decline appeared to be similar across nearly all subgroups evaluated; however, the effect of exercise appeared stronger among those without cardiovascular disease.

The researchers also evaluated the association between achieved activity and decline in eGFR and rapid declining kidney function overall and within each trial arm. Participants who were in the highest quartile of step count (≥3,470 steps/d) had an approximately 2 mL/min/1.73 m2 slower decline in eGFR and about one-third reduction in odds of rapid kidney decline versus participants with the lowest step count (≤1,567 steps/d) (odds ratio, 0.62 [95% CI, 0.44 to 0.87]; P=0.005).

“Of particular clinical importance, the benefits of exercise on kidney function were detectable even with relatively modest increases in physical activity,” the study authors wrote, noting that the modest activity was common. “Despite the relative improvements in their step counts, the majority of participants in the physical activity and exercise group would still have been classified as sedentary throughout the follow-up period, and only about 1 in 12 achieved step counts (>5000 steps/d) that would classify them as active based on guideline recommendations for physical activity in older adults.”