Higher cardiorespiratory fitness = slower age-related decline in kidney function

 As Japan's population continues to age, age-related declines in kidney function and chronic kidney disease (CKD) are becoming increasingly prevalent, underscoring the need for effective preventive strategies. Despite growing interest in the health benefits of cardiorespiratory fitness, its relationship with future kidney function decline remains poorly understood, particularly among individuals with preserved kidney function. To address this gap, researchers investigated whether higher cardiorespiratory fitness, a measure of whole-body endurance capacity, is associated with a slower age-related decline in kidney function.

The study evaluated cardiorespiratory fitness using a submaximal cycling exercise test in 198 adults with preserved kidney function living in and around Ibaraki Prefecture and monitored changes in kidney function over a 5-year period. The results demonstrated that higher cardiorespiratory fitness was associated with a slower age-related decline in kidney function. Notably, this association remained significant after adjusting for potential confounding factors, including age, sex, body composition, smoking status, comorbidities, and baseline kidney function. The study also found that participants with higher cardiorespiratory fitness were less likely to experience a clinically meaningful decline in kidney function of ≥20% during the follow-up period.

These findings suggest that maintaining cardiorespiratory fitness while kidney function remains preserved may help protect kidney health later in life. From a sports medicine perspective, the results provide new insights into strategies for extending healthy life expectancy and mitigating age-related declines in kidney function, potentially contributing to the prevention of CKD. However, because this was an observational study, the findings do not establish a causal relationship between cardiorespiratory fitness and decline in kidney function.