Exercise Is Good for All Stages of Kidney Disease

Loss of muscle mass is a common early complication of chronic kidney disease (CKD), but exercise and lifestyle interventions can help stave off that process.

“Encouraging people with CKD to be less sedentary is absolutely crucial,” said James Burton, MBChB, MD, a professor in renal medicine and honorary consultant nephrologist with the University of Leicester, in England.

Expert supervision of structured exercise programs results in greater compliance and potentially better outcomes for patients with kidney disease, he said. “But it’s really important that we appreciate that a one size [program] does not fit all,” he added. “Really, we should be thinking about a combination of self-management, home-based and center-based exercise, and a mixture of aerobic, resistance, and potentially balance training as well to get the very most out of the interventions to improve outcomes for our patients.”

Skeletal muscle wasting, and muscle dysfunction, starts earlier than when most nephrologists think about it as they’re sitting with people in clinic, Burton said. Such sarcopenia is associated with lower levels of physical functioning, lower exercise capacity, and increased morbidity and mortality.

Maintenance of muscle mass is a balance between protein synthesis and protein degradation, he said. An imbalance can lead to loss of muscle mass or atrophy of individual muscle fibers. Individual processes contributing to a reduction in protein synthesis include a loss of amino acids through dialysis and hormonal derangements, as well as a sedentary lifestyle that starts the cycle of increased muscle wasting (1). Factors contributing to an increase in protein degradation include insulin resistance, metabolic acidosis, vitamin D deficiency, and increases in oxidative stress. Once a person reaches that state, muscle loss and wasting can lead to weakness, a reduction in muscle strength, and ultimately to low physical performance and potentially to disability and frailty, Burton said.

The good news for CKD patients is that exercise can improve muscle mass and physical functioning, he said. Among CKD patients not using dialysis, a 12-week study that combined resistance and aerobic training for three 30-minute sessions a week found that the exercises led to improvements in muscle strength, muscle volume, and exercise capacity (2). Another 4-month study measured the results from endurance training plus either balance or strength training (3). Sarcopenia did not progress over 12 months in either group. Both groups experienced reductions in fat mass, and the participants who did balance training had an increase in lean mass.

Our knowledge of how dialysis affects the muscles is fairly limited, Burton said, but the process does have a significant impact on physical function, and people using dialysis traditionally become more sedentary, which also can have an impact on mortality. Exercise can help with these patients as well.

One study found a 30% reduction in mortality among patients undergoing dialysis who exercised either two to three, or four to five, times per week (4). Another trial, presented last year at UK Kidney Week, found that patients randomized to exercise for half an hour between dialysis sessions for 6 months had a mean 11.1-g reduction in left ventricular mass (5)—“a good surrogate outcome for cardiovascular events and mortality,” Burton said.

Exercise even can help patients with kidney failure. A 2002 study split patients into three groups for 6 months. One group was assigned to a center-based exercise program delivered by specialists three times a week on nondialysis days, one received an exercise program delivered by specialists on dialysis days, and one was asked to complete a moderate-intensity home-based program 5 days a week and was provided with individual instruction (6). Although more participants (24%) dropped out of the first group compared with the others (17%), those who completed the study had increased measures of peak oxygen consumption and exercise time.

Groups such as Kidney Disease: Improving Global Outcomes (KDIGO) have guidelines recommending that people with CKD be encouraged to exercise at least 30 minutes five times a week to achieve a healthy weight, and other groups suggest exercising three times a week or between dialysis sessions as a person is able. Overall, there is a lack of robust randomized trials for this, Burton said, and getting patients to be more active remains a challenge.

“I think we all know that exercise is good for people, but it’s only good for people if they actually take part,” he said.

View Full Size

Citation: Kidney News 12, 12

• Download Figure
• Download figure as PowerPoint slide

It’s important to explain to patients that they can get exercise in many ways, from walking to other social activities, not just by going to a gym, Burton said. Looking at barriers to exercise, he said, “People with CKD are worried about comorbidities and poor health. It’s up to us as their healthcare professionals to highlight to them the importance of exercise in abrogating some of those things that we know are going to make their multimorbidity and outcomes potentially worse.”