Physical Activity, Function, and Exercise-Based Rehabilitation for People on Dialysis

Introduction

The focus on increasing physical activity for those people with a high burden of cardiometabolic) conditions and complications (i.e., kidney failure, diabetes, cardiovascular comorbidities) for managing symptoms and maintaining physical well-being is at an all-time high. Rehabilitation, meaning recovering or restoring what is necessary to get on with living, has been a low priority in most dialysis facilities, and the inclusion of integrated rehabilitation programs for dialysis patients is not routinely offered as part of patient care. The Kidney Disease Outcomes Quality Initiative (KDOQI) practice guidelines for physical activity states that all dialysis patients should be counseled and regularly encouraged by nephrology and dialysis staff to increase their level of physical activity. Please refer to KDOQI guideline 14: “Smoking, Physical Activity, and Psychological Factors.”

A published British Association of Sport and Exercise Science (BASES) expert statement in 2015 on exercise for people with chronic kidney disease (CKD) suggests that every stable patient with CKD, irrespective of age, gender, comorbidities, or prior exercise experience, should be provided with specific written advice on how to safely and effectively increase physical activity to (i) enhance confidence and self-efficacy in performing physical activities; (ii) attenuate deterioration of physical function and associated limitations in activities of daily living (ADLs); (iii) increase physiological reserve; (iv) reduce comorbid events; and (v) enhance quality of life (QOL). The focus of this chapter is on the core principle of exercise for reversing the effects of physical deconditioning and optimizing physical functioning and QOL in patients on dialysis.

Definitions

Physical function is often used as a term to encompass many concepts. Physical function is best defined as an individual’s ability to perform activities required in their daily life. Physical functioning is determined by many factors, including physical fitness (cardiorespiratory fitness, strength, and flexibility), sensory function, clinical condition, environmental factors, and behavioral factors. Physical fitness is a set of attributes people have or achieve that relates to the ability to perform physical activity. One of these attributes is cardiorespiratory fitness (often referred to as exercise capacity ), which relates to the ability of the cardiac, circulatory, and respiratory systems to supply and use oxygen during sustained physical activity.

Physical functioning can be improved with regular physical activity or exercise training. Exercise (physical activity) is defined as bodily movement produced by the contraction of skeletal muscle that substantially increases energy expenditure. Exercise training is planned, structured, and repetitive bodily movement done to improve or maintain one or more components of physical fitness or to obtain other health benefits. Increased physical activity can be considered exercise training, although increased physical activity can also result from unstructured increases in movements throughout the day. The use of the term physical activity may be less intimidating to dialysis patients who are typically elderly and often frail or chronically fatigued. However, exercise training is appropriate and recommended for dialysis patients due to their extremely low levels of physical functioning and exercise capacity. Table 60.1 outlines these definitions.

Physical Activity and Function

Physical inactivity is associated with a significantly higher risk of premature morbidity and mortality and poorer QOL outcomes in people requiring hemodialysis (HD). There is an increased age profile of incident patients on HD, with a median age of 65 years, and an associated presence of the clinical syndrome of frailty. This syndrome is characterized by persistent fatigue, weight loss, muscle weakness, severe functional limitations, and low physical activity levels, many of which often deteriorate further as time on dialysis increases. This translates into an impaired capacity to undertake ADLs and to live independently and to impaired QOL. Physical function, regardless of how it is measured, is low in patients at all stages of CKD. Higher levels of physical function and habitual physical activity have been shown to be related to enhanced longevity, less morbidity, lower hospitalization rates, and enhanced QOL, in patients receiving dialysis-based kidney replacement therapy.

Exercise Rehabilitation

Exercise rehabilitation has started gaining some attention as an appropriate and safe option to improve physical function, which is an integral component of physical independence and QOL, by aiming to alleviate muscle weakness/dysfunction and maintain adequate cardiorespiratory fitness and thus impact on less cardiovascular morbidity and mortality. Physical inactivity is a modifiable risk factor, and exercise interventions designed to increase physical activity and fitness components and reduce sedentary behaviors in patients at risk of cardiovascular disease may improve health-related outcomes and be cost effective in the longer term. A recent report of practice-based evidence that incorporated a multicomponent exercise rehabilitation program in clinical patient care path for people in all stages of CKD revealed that people who completed the program and improved fitness had a significantly longer cardiovascular event-free survival time over an observation period of 34 months.

HD therapy enforces regular sedentary behavior three times a week, for up to 4 hours at a time. A main facilitator to intradialytic exercise would, therefore, be the reduced time and transport cost burden to patients as exercise time can be incorporated during dialysis therapy. There is also the potential for an improvement in dialysis efficiency and enhanced solute removal. Current understanding of UK-based practices indicates that provision of physical activity/exercise programs for patients with CKD appears to be extremely varied across the UK and is often only an option for patients in an area where research studies are being conducted. There are now 15 published systematic reviews and meta-analyses that have evaluated the overall effectiveness of exercise interventions on various health-related outcomes in patients from all stages of CKD and following transplantation and in patients on HD only. Koufaki et al. published a systematic review and synthesis of the research evidence in an attempt to translate the findings from these systematic and meta-analytic reviews, together with any recently published research evidence, to provide some well-informed recommendations on exercise rehabilitation in CKD. The reader is directed to these published reviews for an in-depth analysis of the research literature. Some of the associations of physical function and clinical outcomes in dialysis patients are outlined in Table 60.2 .