Physical Activity and Exercise in Chronic Kidney Disease

Abstract

The chronic kidney disease (CKD) population is older, with common comorbidities such as diabetes, hypertension, and cardiovascular disease (CVD). Frailty, low levels of physical function, and low levels of physical activity are related to morbidity and mortality and are well documented in people with CKD. Obesity is common; however, sarcopenic obesity is increasingly recognized. Although physical activity is generally recognized as important, self-perception of actual activity levels is often overstated. Physical activity and exercise should be the core components of the management of people with CKD.

The editors acknowledge the contribution of Kirsten L. Johansen and Patricia Painter to this chapter in Nutrition in Kidney Disease, Second Edition, Nutrition and Health, DOI https://doi.org/10.1007/978-1-62703-685-6_1, © Springer Science+Business Media New York 2014.

Case Study

The following case study highlights some of the complexities related to exercise prescription in hemodialysis patients: A 44-year-old African-American male with ESKD has been on maintenance hemodialysis for 2 years. He is morbidly obese (BMI = 38.5 kg/m²) and has been told he needs to lose ~ 50 pounds (20 kg) to become eligible for a transplant. He is hypertensive (pre-dialysis BP = 170/100), and his interdialytic weight gain for the past month has averaged 5.0 kg. He has occasional intradialytic hypotension and/or cramping during treatment, which is normally resolved by saline treatments or prematurely stopping ultrafiltration. The patient also complains of post-dialysis fatigue and poor sleep patterns. He acknowledges that he does not exercise. He also describes his diet as poor, including “a lot of fast food and frozen meals,” and rarely cooks. He is divorced and lives with his 22-year-old son who is also overweight and does little exercise. The patient expresses that he is very motivated to lose the weight needed to become eligible for a transplant and has asked for help in developing an exercise program to assist with this.

Medications

Darbepoetin, Amlodipine, Clonidine, Losartan, and sevelamer carbonate.

Laboratory Values

Albumin, 3.8 mg/dL; hematocrit, 36.0%; hemoglobin, 10.8 g/dL; serum P, 4.8 mg/dL; serum K, 5.5 mmol.

Physical Evaluation

Physical activity history: The patient currently does not engage in any physical activity. He played football and basketball in high school, but has not been involved in any structured exercise program since then. He previously had a construction job and was fairly active at work, but he lost his job after starting dialysis and is now completely sedentary, except for occasional trips (once a month) to a grocery store that is just a few blocks from his home. He lives in a neighborhood in which he does not feel safe walking at night, but is comfortable walking during the day. He would like to join a gym but does not feel he can afford it.

Physical function testing:

Four-meter gait speed: 1.0 m/s < 1.1 m/s indicates impaired mobility [34]; 1.21 m/s is the average age/gender comfortable gait speed [154]; 0.98 m/s is average in 40- to 50-year-old hemodialysis patients [34]. Thus, his gait speed is 83% of expected.

Chair stands (time for five repetitions): 9.5 s > 13.7 s indicates impaired function [155]; 7.6 s is age-expected time [156]. Thus, his performance is 80% of expected.

Six-minute walk distance: 445 m < 460 m indicates impaired mobility [34]; 570 m is the average age-gender reported distance [157]. Thus, his distance is 78% of expected.

Patient-stated activity goals:

Short-term: Start lifting weights and/or walking to the store 3 days a week, preferably on non-dialysis days when he has the most energy.

Long-term: Lose 50 pounds to become eligible for a transplant.

Case Questions and Answers

• 1. Prior to developing a physical activity plan for this patient, what considerations would you have?

  Answer: Prior to developing a physical activity plan for this patient, it is important to assess his physical activity history, complete a functional assessment, and also identify activity-related goals and barriers.

• 2. Is exercise alone likely to help this patient achieve his weight loss goal?

  Answer: The situation outlined above is rather common. As stated above, there is debate in the literature as to the pros and cons of weight loss for renal transplant eligibility, and there are no clear guidelines for doing so [126,127,128,129,130,131,132]. Regardless, his goal of losing 50 pounds to become transplant eligible is unlikely to be resolved through exercise alone. According to the current physical activity recommendations, losing weight through exercise alone requires 60–90 minutes of daily exercise [158], which is an unrealistic expectation in any reasonable time frame. As such, some reduction in caloric intake is needed to facilitate the required weight loss.

  Complicating matters, the patient has excessive fluid intakes contributing to volume overload, and this is contributing to his intradialytic symptoms, including premature cessation of ultrafiltration, post-dialysis fatigue, and disturbed sleep patterns. Results from the physical function testing indicate he may have mildly impaired function, but is not frail, so should have few if any restraints on his physical activity.

• 3. What would be a realistic exercise prescription for this patient?

  Answer: An appropriate prescription for this patient should include a plan to slowly increase his physical activity levels, followed by structured exercise as he progresses. An excellent example of a strategy to increase the patient’s physical activity levels is outlined in the study by Tawney et al. [152]. A realistic initial goal could be to develop strategies for the patient to build toward accumulating at least 30 minutes of self-selected physical activity per day. Activity goals should be set that consider the patient’s preference and lifestyle, barriers to physical activity should be identified, and supports for addressing these barriers, such as inclusion of family or other care providers, should be considered. An intriguing possibility would be to inquire if his son would be willing to exercise with him on occasion, especially since he also has a weight problem. For the first several weeks, modest goals such as walking around the neighborhood on his non-dialysis days should be considered, starting from modest goals of 10–15 minutes several days a week. As the patient has a goal of improving his strength, simple at-home exercises such as push-ups and body weight squats can be incorporated into his daily routine, perhaps while he watches television.

• 4. What dietary interventions would you suggest to support the exercise prescription?

  Answer: A dietitian should also be consulted to help safely manage his weight loss, which should include a focus on how to reduce his sodium intake to reduce interdialytic weight gain and chronic volume overload. This could include walking to the grocery store and tips on how to shop for low-sodium and lower-calorie food products, to help facilitate weight loss. Short-term weight loss goals should be considered, such as losing 1–2 pounds per week. This will be facilitated by changes in his diet that could result from purchasing more food at the grocery store and eating out less. A balanced approach to higher diet quality and less processed foods should be encouraged with an individualized lower-calorie plan including whole grains, legumes, dairy, fruits, and vegetables. Cooking is another form of physical activity that increases energy expenditure a modest amount and contributes to an overall activity plan.

• 5. How would you adjust the exercise prescription as the patient starts to make progress?

  Answer: As the patient sees progress, activity and nutrition goals can be adjusted as necessary. Aerobic activity should increase to at least 150 minutes per week. If the patient has reduced his dietary intake, specifically from calorically dense processed food, he should slowly start to lose weight, but in a reasonable manner that should help preserve lean mass. Incorporating some resistance training into his physical activity plan can also help maintain muscle. Moreover, reduced sodium intake from eating less processed food should reduce interdialytic weight gains (IDWGs) and subsequently ultrafiltration rates during dialysis. This should reduce post-dialysis fatigue and give him more energy to exercise, possibly even after dialysis.

This case study is meant to highlight the many complexities of prescribing exercise in dialysis patients. It is clear that a comprehensive approach to physical activity is required to significantly improve the health and QOL of many hemodialysis patients. Individualized approaches to an exercise prescription are needed, especially when weight loss is an objective.