Successful renal transplantation reduces mortality rates. However, the decline in the estimated glomerular filtration rate (eGFR) after transplantation is strongly associated with premature mortality in renal transplant recipients (RTRs). Physical activity (PA) is a modifiable lifestyle factor with the potential to maintain or improve eGFR. However, the effects of the type or intensity of PA and sedentary behavior (SB) on eGFR in RTRs remain unclear. The purpose of this study was to clarify the association between accelerometry-measured PA and SB and eGFR in RTRs using isotemporal substitution (IS) analysis.
A total of 82 renal transplant outpatients participated in this cross-sectional study, among which 65 (average age, 56.9 years; average time post-transplant, 83.0 months) were finally analyzed. All RTRs wore a triaxial accelerometer to measure PA for seven consecutive days. The measured PA was classified based on intensity into light PA (LPA), moderate-to-vigorous PA (MVPA), and SB. The association of each type of PA with eGFR was examined using multi-regression analyses of single-factor, partition, and IS models. The IS model was applied to examine the estimated effects of substituting 30 min of SB with an equal amount of time of LPA or MVPA on eGFR.
The partition model showed that MVPA was an independent explanatory variable for eGFR (β = 5.503, p < 0.05), and the IS model identified that the substitution of time spent in SB with MVPA led to improvements in eGFR (β = 5.902, p < 0.05).
The present study suggests that MVPA has an independent and positive association with eGFR, and replacing 30 min of SB with MVPA after renal transplantation might lead to the maintenance or improvement of eGFR in RTRs.

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