What Is Maintenance HD?

The kidneys do several important jobs in the body, including helping to control blood pressure and making red blood cells, and removing waste products and extra water from the body to make urine. If a person’s kidneys stop working (known as “kidney failure”), they will need kidney replacement therapy, in the form of dialysis or kidney transplant, to survive. Kidney failure treated in this way is referred to as ESRD. If a person is treated with maintenance HD, they usually have HD two or three times per week, often in a healthcare setting. During the HD process, the person’s blood leaves their body, goes through a filter in a machine that removes waste products and excess water, and the purified blood is then returned to their body.

Why Is Exercise Important for People Receiving Maintenance HD?

Regular exercise is important for everyone. Among other benefits, people who exercise regularly report that they sleep better and have more energy and muscle strength. Having ESRD has been shown to decrease a person’s level of physical activity and quality of life, partly because people with ESRD are likely to have other medical conditions (termed “comorbidities”). These may or may not be linked to their ESRD, and may contribute to them being physically inactive. However, it is widely acknowledged that people receiving maintenance HD may benefit from increasing their levels of physical activity. Regular exercise may benefit people with ESRD by improving their heart function, muscle strength, and blood pressure control, reducing the risk of diabetes, and helping to prevent anxiety and depression. The benefits of regular exercise described by the general population are similarly reported by people who receive maintenance HD. Moreover, they also perceive that they have better quality of life than those that don’t exercise because they are more able to do the things that they want and have to do in their daily lives (known as “physical function”).

What Is the Evidence that Exercise Can Benefit People Receiving Maintenance HD?

A number of research studies have been conducted that have sought to determine how exercise can benefit patients receiving maintenance HD. Most of these have involved patients using exercise bikes to cycle during HD sessions (termed “intradialytic cycling”), while some include at-home walking schedules and/or light resistance training. Although they have reported that exercise can improve physical function, cardiovascular health, and quality of life, many of the studies have only looked at small numbers of patients. Some have also suggested that the amount and intensity of the exercise that the participants are asked to do may not be enough for there to be significant improvements in their health or quality of life, and that this may be partly due to the comorbidities that they may have. Fatigue, muscle cramping, poor physical function, depression, and a lack of motivation, possibly in addition to serious comorbidities, have all been suggested to be barriers to exercise for patients receiving HD.

Nonetheless, the recently published CYCLE trial has shown that 6 months of intradialytic cycling improved the structure and function of the heart of patients receiving maintenance HD. This was shown by magnetic resonance imaging, with reductions seen in arterial stiffness and the mass of the left ventricle (one of the chambers in the heart), which are both associated with increased risk of a range of cardiovascular problems. Several other recent studies have reported that intradialytic exercise can improve a variety of patient-reported outcomes in people receiving maintenance HD, including reduced cramping, fatigue, and restless leg syndrome.

How Can People Receiving Maintenance HD Exercise Safely?

It is important that people receiving maintenance HD consult their healthcare team before starting a new program of exercise. The National Kidney Foundation suggests walking, swimming, aerobic dancing, and cycling (on an exercise bike or outside) to be good options because they involve continuously moving large muscle groups. Low-level strengthening and stretching exercises may also be good options, although heavy lifting should be avoided. As with any new exercise program, starting gently and building up from there is best. As little as 10 minutes of exercise, 3 days per week on non-consecutive days can have a positive effect. Importantly, exercise should be paused until the healthcare team can be consulted if the person’s dialysis or medicine schedule or physical condition changes.

How Is Exercise Incorporated into HD Care?

Although there are examples of exercise programs for people receiving maintenance HD in several countries, including Portugal, Germany, Mexico, and parts of Canada, implementation of exercise programs by healthcare providers worldwide remains low. It has been reported that less than 10% of dialysis centers offer exercise programs. This has been attributed by some to nephrologists possibly not feeling confident in their abilities to discuss the topic with their patients, and patients feeling that they don’t have the knowledge to exercise safely. The authors of the review article suggest that lifestyle interventions like exercise programs could be incentivized in HD centers if funding policies were changed to reward improvements in quality of life metrics as well as biochemical factors. Altering the physical environments in HD clinics, to be more inspiring and encouraging, could also help, particularly if exercise equipment was added to a designated space for exercise.

Take-Home Message for Patients

Exercise is as important for people receiving maintenance HD as anyone else and can have a wide range of benefits, including on their quality of life. People receiving maintenance HD who are interested in increasing their activity levels should consult their clinical team for advice on how to do this safely and consider accessing support and guidance from specialist organizations.