Incremental short maximal exercise increases urinary liver‐type fatty acid‐binding protein in adults without CKD

Abstract

Exercise‐induced redistribution of tissue blood flow decreases the renal blood flow in an exercise intensity‐dependent manner. However, the acute effects of incremental short maximal exercise on renal tubular conditions remain unknown. The purpose of this study was to investigate the acute effects of incremental short maximal exercise on the urinary liver‐type fatty acid‐binding protein, which is a highly sensitive tubular biomarker that correlates excellently with peritubular capillary blood flow. A total of 116 adults (aged 24‐83 years) without chronic kidney disease performed the incremental short maximal exercise using a cycling ergometer, wherein the exercise sequence consisted of commencing with a 2‐min workout period at 20 W (as a warm‐up period) and then followed by a 10‐20 W increase every 1 minute until termination criteria were reached. Urinary samples were gathered before and immediately after the exercise to evaluate the concentrations of urinary creatinine, albumin, and liver‐type fatty acid‐binding protein. Urinary excretion levels of albumin and liver‐type fatty acid‐binding protein were significantly increased post‐exercise (P < .001 and P = .008, respectively). Furthermore, the % change in urinary liver‐type fatty acid‐binding protein levels after exercise was found to correlate independently with age, estimated glomerular filtration rate at baseline, and the % change in urinary albumin (Model R2 = 0.451, P < .001). Our findings suggest that incremental short maximal exercise may lead to acute slightly adverse effects on tubular conditions, especially in young adults or adults with lower renal function, even without chronic kidney disease.

Changes in Novel AKI Biomarkers after Exercise. A Systematic Review

“…Only two studies in healthy populations concerning changes in uL-FABP after exercise have been published. uL-FABP was significantly increased after incremental short maximal exercise on a cycling ergometer in a group of 116 adults of variable age (24-83 years) in a study published by Kosaki et al In this experiment, uL-FABP/uCr changes were independently correlated with albuminuria, which supported previous observations that protein overload in the proximal tubule may cause an increase in uL-FABP [53]. After short exercise (one leg calf-rise exercise), Kanda et al did not find any changes in uL-FABP [37].…”

“…It appears to be a promising biomarker for both the diagnosis and prediction of AKI and its outcomes among critically ill patients [5,8,9]. L-FABP is localized in the proximal tubule and secreted into urine in response to a number of different intrarenal stresses, such as proteinuria, hypoxia, hyperglycemia, hypertension and oxidative stress [37,53,54].…”

“…It is known that all urinary markers can be diluted, and, e.g., normalization of albuminuria is a standard procedure. In some studies, un-normalized values are used, but most authors normalized AKI markers to creatinine, osmolality, urine flow or cystatin C [18,23,26,27,34,35,40,[44][45][46][47][48]51,53]. All these approaches had some limits.…”

The moderate‐intensity continuous exercise maintains renal blood flow and does not impair the renal function

“…Several studies have shown that the urinary acute kidney injury (AKI) biomarkers such as urinary liver‐type fatty acid‐binding protein (L‐FABP) and kidney injury molecule‐1 (KIM‐1) are increased following exercise (Kosaki et al, 2020 ; Wołyniec et al, 2018 , 2020 ). These biomarkers are highly sensitive urinary biomarker reflecting the degree of glomerular and/or tubular damage, these results indicate the possibility that glomerular abnormality, tubular hypoxia, and tubulointerstitial damage are caused by exercise.…”

“…These biomarkers are highly sensitive urinary biomarker reflecting the degree of glomerular and/or tubular damage, these results indicate the possibility that glomerular abnormality, tubular hypoxia, and tubulointerstitial damage are caused by exercise. However, the changes of these biomarkers are dependent on the duration and intensity of exercise, most studies investigated changes in AKI biomarkers following high‐intensity exercise involved in reduction in RBF (Kosaki et al, 2020 ; McDermott et al, 2018 ; Poussel et al, 2020 ; Wołyniec et al, 2018 , 2020 ). It is considered that examining the influence of moderate‐intensity continuous exercise on AKI biomarkers is of considerable clinical important.…”