Physical Activity and Exercise for Cardiorespiratory Health and Fitness in Chronic Kidney Disease

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TL;DR

This narrative review examines the evidence for physical activity and exercise in chronic kidney disease (CKD) patients, focusing on cardiorespiratory health and fitness. Aerobic exercise improves peak oxygen consumption (VO2peak) by approximately 2 mL⋅kg⁻¹⋅min⁻¹, while resistance exercise effectively increases muscle strength and mass, though neither modality fully restores fitness to normative levels. The review highlights that physical inactivity is highly prevalent in CKD (28% vs. 13.5% in non-CKD individuals) and is strongly associated with increased cardiovascular and all-cause mortality, underscoring the need for CKD-specific exercise guidelines.

Full summary

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**Background:** Chronic kidney disease (CKD) affects an estimated 10–15% of the global population, with the majority of adults unaware of their condition. Cardiovascular disease (CVD) is the leading cause of death in CKD patients, with approximately 50% of those with CKD G4 and G5 having CVD. Traditional CVD risk factors are elevated in CKD, but randomized controlled trials targeting these factors have shown limited benefit. Physical inactivity is a major modifiable risk factor, with 28% of CKD individuals reported as physically inactive compared to 13.5% of non-CKD individuals (NHANES III). This narrative review discusses the evidence for physical activity and exercise interventions on cardiovascular outcomes and fitness across the spectrum of CKD.

**Methods:** This is a narrative review synthesizing existing literature on physical activity, aerobic exercise, resistance exercise, and combination exercise in CKD patients, including those with end-stage kidney disease (ESKD) and kidney transplant recipients. The review covers epidemiology, physiological mechanisms, clinical outcomes, and barriers to exercise participation.

**Key Results:** Cardiorespiratory fitness is severely compromised in CKD, with a 17% reduction in VO2peak observed in mild-to-moderate CKD compared to age-predicted values. Aerobic exercise improves VO2peak by approximately 2 mL⋅kg⁻¹⋅min⁻¹, though values remain below normative levels. In ESKD patients, VO2peak is a strong predictor of survival over approximately 3.5 years. Resistance exercise effectively increases muscle strength, type I and II muscle fiber cross-sectional area, and total body potassium, and can counteract catabolism even in the presence of low-protein diets. Combination exercise (aerobic + resistance) has shown improvements in VO2peak (e.g., from 16.8 to 22.3 mL⋅kg⁻¹⋅min⁻¹ over 12 months in hemodialysis patients) and may slow eGFR decline, though results are inconsistent. Physical activity levels are inversely associated with all-cause and CVD mortality; each 60-minute increment in weekly physical activity was associated with a 0.5% slower decline per year in eGFR over a median follow-up of 3.7 years. Exercise also reduces inflammatory markers: 8 weeks of progressive resistance exercise reduced the inflammatory response to acute exercise, and 12 weeks of resistance exercise plus low-protein diet reduced serum CRP and IL-6. However, some studies report no change in inflammatory markers. Barriers to exercise include poor physical condition, fatigue, lack of awareness of guidelines, and comorbidities; facilitators include encouragement from healthcare providers and peer support.

**Clinical Implications:** Physical activity and exercise should be incorporated into CKD care to improve cardiorespiratory fitness, muscle strength, and potentially slow kidney function decline. Even if patients cannot meet general physical activity guidelines (150–300 minutes/week of moderate-intensity aerobic activity plus muscle-strengthening activities on 2+ days/week), increasing activity and reducing sedentary time likely confer health benefits. The review recommends that kidney care programs offer exercise plans prescribed by exercise professionals. Sequencing resistance exercise before aerobic exercise may be advantageous for frail patients, though this requires further study. Future research should establish CKD-specific exercise guidelines, clarify mechanisms of exercise adaptation, and develop strategies to improve adherence.