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Implications for practice and research
■ There is robust evidence for significant benefits of regular exercise training on physical fitness and function in patients receiving renal replacement therapy (RRT).
■ Data support the use of regular exercise to improve cardiovascular health in patients undergoing renal replacement therapy albeit robust data from large scale randomised controlled trials (RCTs) designed to investigate cardiovascular health outcomes are lacking.
■ Clinicians should counsel patients with chronic kidney disease (CKD) to increase physical activity levels and inform them that there is scientific evidence that regular exercise benefits health. Potential referral to clinical exercise programs should be considered.
■ Future studies should stratify participants based on CKD aetiology and stage, include sufficient sample size, and employ a rigorous RCT design using exercise as an adjunctive therapy versus pharmacotherapy alone in a translational setting. Dialysis nurses have a unique opportunity to lead the translation of intradialytic exercise from research to regular clinical practice.
CKD represents a significant healthcare problem throughout the world. The incidence of CKD is projected to increase substantially worldwide during the next decade and contribute significantly to increased healthcare costs. Patients with CKD have very low-physical fitness and function, significantly reducing their ability to perform activities of daily living. Reduced physical fitness and physical activity levels have been shown to predict hospitalisation and mortality. The benefit of regular exercise on physical fitness in patients with CKD has been well documented.
This Cochrane review assessed the effects of regular exercise training on health outcomes in adults with CKD (stage 1 to 5 or kidney transplantation). Thirty-two randomised or quasi-RCT assessing various health related outcomes in response to exercise were pooled and meta-analysed. Studies were included in the meta-analysis if the intervention consisted of either cardiovascular or resistance exercise training, alone or combined, lasting 8 weeks or longer. Outcome variables included physical fitness and function, cardiovascular health variables, nutritional variables, body mass indices, health-related quality of life (HRQL) and skeletal muscle morphology.
Meta-analysis found a robust improvement in physical fitness and function. Pooled analysis further indicated improvements in skeletal muscle strength, resting blood pressure levels and heart rate, peak heart rate, serum and prealbumin and walking capacity. These findings were less robust due to significant heterogeneity between studies, lack of RCTs and small sample size. Due to lack of availability of RCTs, other outcome variables had insufficient evidence. The authors concluded that regular exercise training combining cardiovascular and resistance exercise, 30 min, three times/week results in significant benefits in physical fitness, walking capacity, some cardiovascular health and nutritional variables and HRQL.
The present study adds further evidence of the importance of including regular exercise in the treatment regimen for patients with CKD. Despite numerous studies and reports indicating the benefits of exercise in patients undergoing RRT, very few dialysis units offer intradialytic exercise, referral to clinical exercise programs, or even provide counsel to increase physical activity. The present study should encourage clinicians to fully implement the K/DOQI's practice guidelines to counsel and encourage patients to increase their level of physical activity.1 It should be noted that the majority of published studies included in this meta-analysis were small and enrolled patients were undergoing RRT. Relatively few studies have included patients with stage 1 to 4 CKD and we know relatively little about differences in response to exercise between various aetiologies of CKD, which limits the generalisability of findings to dialysis patients. Moreover, there have been no RCTs that have been specifically designed to investigate cardiovascular health outcomes. The few studies that have investigated cardiovascular health variables have been small, employed various interventions or testing methods, performed secondary analyses and participant baseline characteristics have varied substantially. Although the use of pooled analysis is a powerful tool to combine the results of many smaller studies, it should be emphasised that results from studies may differ based on baseline health variables, data collection techniques, intervention protocols and results from studies conducted prior to availability of recombinant erythropoietin. One additional area of concern is the relative high number of studies that presented with moderate–high risk of bias (82% of studies included). This indicates a strong need for future studies to include larger sample sizes, and include rigorous and carefully designed RCT. Despite these limitations, it is clear the regular exercise provides many benefits in patients with CKD undergoing RRT.
Funding Dr Bronas is funded by NIH-NIDDK grant #DK082638.
Competing interests None.