Effect of exercise on kidney-relevant biomarkers in the general population: a systematic review and meta-analysis

Objective: Physical activity (PA) has been generally recognised as beneficial for health. The effect of a change in PA on kidney biomarkers in healthy individuals without kidney disease remains unclear. This manuscript synthesised the evidence of the association of changes in PA with kidney biomarkers in the general population free from kidney disease.

Design: Systematic review and meta-analysis.

Data sources: Embase, PubMed, MEDLINE and Web of Science databases were searched from inception to 12 March 2023.

Eligibility criteria for selecting studies: Studies of longitudinal or interventional design were selected initially. The following studies were excluded: (1) case-control studies, (2) studies where PA was measured at a single time point, (3) populations with known kidney disease, (4) studies evaluating the impact of a single episode/event of PA and (5) non-English language studies.

Data extraction and synthesis: Two independent reviewers extracted data from a pre-designed table and assessed the risk of bias using the Cochrane Risk of Bias tool. Data were pooled using a random-effects model. Hedge's g was used to synthesise effect sizes and obtain an overall estimate. Heterogeneity between studies was measured using I². Funnel plots and Egger's test were performed to evaluate the risk of biased results.

Results: 16 interventional studies with randomised or non-randomised designs involving 500 participants were identified. The median follow-up was 84 days. 10 studies were at high risk of bias. Studies with low quality were published prior to the year 2000. Changes in PA were found only to have a positive association with serum creatinine (SCr) (Hedge's g=0.69; 95% CI 0.13, 1.24; I²=81.37%) and not with plasma renin activity (PRA), urea, or urine albumin-to-creatinine ratio (UACR). The positive association was only observed in people with obesity and those who exercised for more than 84 days.

Conclusions: Higher levels of PA are associated with increased SCr levels in healthy people. It remains unclear if this association is related to impaired kidney function or gain in muscle mass, as data on other kidney biomarkers did not support a certain link.

Prospero registration number: This review has been registered on PROSPERO (CRD42023407820).