Kidney transplantation in adults: Physical activity in kidney transplant recipients

INTRODUCTION — Physical inactivity is widely recognized as an important, modifiable risk factor for multiple comorbidities among kidney transplant candidates, including cardiovascular disease, hypertension, obesity, insulin resistance, and depression. However, kidney transplant candidates experience a high burden of physical deconditioning due to years of deconditioning while experiencing chronic kidney disease. (See "Uremic myopathy and deconditioning in patients with chronic kidney disease (including those on dialysis)".)

This topic will review the effects of physical inactivity among kidney transplant candidates and recipients and discuss pre- and posttransplantation measures to assess physical performance and increase physical activity. The effects of a sedentary lifestyle and the effects of exercise in the general adult population are discussed elsewhere:

●(See "The benefits and risks of aerobic exercise".)

●(See "Physical activity and exercise in older adults".)

●(See "Obesity in adults: Role of physical activity and exercise".)

TERMINOLOGY

●Physical activity – Any bodily movement that results in energy expenditure, including movement that occurs at rest, sleep, work, leisure, or exercise.

●Physical fitness – A set of physical attributes that enables one to perform daily physical activities. Health-related components of physical fitness include cardiorespiratory endurance, muscular strength and endurance, flexibility, and body composition. Skill-related components of fitness include agility, balance, coordination, power, and reaction time. (See "Exercise for adults: Terminology, patient assessment, and medical clearance", section on 'Exercise terminology'.)

●Physical function – The ability of an individual to perform activities required in daily life.

PHYSICAL ACTIVITY AMONG TRANSPLANT CANDIDATES AND RECIPIENTS

Physical activity levels — Immediately prior to transplantation, kidney transplant candidates have lower levels of physical activity compared with healthy adult populations. After transplantation, physical activity increases but still remains lower than that seen in the general population and disproportionally lower than expected for the recovery in kidney function. As an example, in one study of 32 kidney transplant recipients, physical activity levels immediately before transplant (as measured by patient-reported questionnaire) were between 18 and 35 percent lower than those of age-matched healthy controls [1]. Physical activity levels initially decreased in the first month posttransplantation but subsequently increased over the following year and remained constant up to five years posttransplantation. Patients reported more moderate- and high-intensity physical activity after transplantation.

Subsequent studies using accelerometer-based measures of physical activity have confirmed these findings and also shown that kidney transplant recipients often do not meet recommended levels of physical activity [2]. While one study reported that kidney transplant recipients are more physically active than patients with end-stage kidney disease (ESKD) undergoing hemodialysis [3], another study failed to replicate these findings [4].

Barriers to physical activity — There are a number of barriers to physical activity in kidney transplant recipients, including a history of pre- and posttransplantation sedentarism, impaired physical functioning, lack of motivation, ongoing fatigue, and pain.

Impact of physical inactivity — Physical inactivity and deconditioning among kidney transplant candidates likely result in decreased physical function and, therefore, a high burden of physical frailty and lower extremity impairment. One multicenter study of 1975 patients with ESKD on the kidney transplant waitlist found that 63 percent were intermediately frail and 18 percent were frail [5]; frailty at the time of transplant evaluation was associated with a twofold increased risk of waitlist mortality. In addition, frailty prior to transplantation has been associated with depressive symptoms [6], delirium [7], longer length of hospital stay [8], early hospital readmission [9] after transplantation surgery, delayed graft function [10-13], mycophenolate mofetil (MMF) intolerance [14], and posttransplantation mortality [15]. Lower extremity impairment among kidney transplant candidates has also been associated with a higher risk of posttransplantation mortality [16].

Postsurgical physical activity has been shown to improve many short-term outcomes in multiple types of surgeries, although only a few, small, single-center "enhanced recovery after surgery" studies that include mobilization have been performed in kidney transplant recipients. Increased physical activity might be expected to prevent several of the known posttransplantation complications such as obesity, posttransplantation diabetes, and bone disease, among others, but supportive data are limited [17,18].

PRETRANSPLANTATION MANAGEMENT

Assessment of physical performance — There is no uniform consensus on whether and how to perform a functional assessment of the potential kidney transplant recipient. The multiyear wait for a deceased-donor kidney makes the assessment more challenging. The optimal approach to assessing physical performance is not known. At our centers, we routinely take a physical activity history that includes frequency, intensity, and type of activity. In patients for whom there is concern for physical debilitation, we use the six-minute walk test to assess physical function (table 1).

Some of the commonly used methods to assess physical performance are discussed below:

●Physical activity – Physical activity can be assessed through either patient-reported questionnaires (such as the Physical Activity Scale for the Elderly [PASE] or Baecke questionnaire) and/or objective measures (eg, heart rate monitors, motion sensors [accelerometers or pedometers], doubly labelled water technique). Patient-reported questionnaires are often preferred in the clinical setting because they are easy to administer and relatively low cost. However, they are limited by their subjective nature and are prone to biases in recall, interpretation, and misclassification. Objective measures are more accurate measures of physical activity but cost more and may require the return of a device after a week of usage.

●Physical function – Physical function can be assessed by patient-reported (eg, 36-Item Short Form Health Survey [SF-36]) or laboratory methods, such as the Short Physical Performance Battery (SPPB; based upon three tests of balance, walk speed, and chair stands), walking speed, grip strength, and Timed Up & Go (TUG) test.

●Physical fitness – Physical fitness, which is the result of both physical activity and physical function, can be measured by physical performance measures using a treadmill or cycle ergometer. In these tests, maximum oxygen uptake is commonly measured to assess physical fitness. However, there are only weak correlations between these measures of physical fitness and physical function.

Pretransplantation physical activity interventions — In general, regular physical activity is appropriate for most adults to maintain health and prevent cardiovascular disease (CVD). In patients who are awaiting a transplant who are found to have low physical performance and activity levels during the transplant evaluation, we suggest a prehabilitation program consisting of physical therapy tailored to the needs and goals of kidney allograft recipients. This physical therapy program should occur weekly for at least two months. Upon completion of the prehabilitation program, we assess the success of this intervention by repeating the six-minute walk test. (See 'Assessment of physical performance' above.)

Prehabilitation is a well-studied presurgical intervention with the goal of enhancing patient functional capacity to improve tolerance for an upcoming physiologic stressor, such as surgery [19]. Prehabilitation training can include a combination of aerobic exercises, strength training, and functional task training to suit individual needs. Prehabilitation may be an effective intervention for kidney transplant candidates because they frequently have long waiting times for a deceased or living donor transplant and because there is a high burden of physical inactivity both pre- and posttransplantation. The optimal approach to prehabilitation is not certain. (See 'Physical activity levels' above.)

Although data are limited, pretransplantation interventions may improve quality of life and posttransplantation outcomes. In a pilot study of 24 kidney transplant candidates, 18 participated in prehabilitation, which consisted of weekly, 40-minute-long physical therapy sessions conducted by a physical therapy assistant at an outpatient rehabilitation center [20]. By two months of prehabilitation, physical activity (assessed by accelerometry) increased 64 percent. Of the five prehabilitation participants who received a kidney transplant during the study, length of hospital stay after transplant surgery was shorter compared with that of matched controls (5 versus 10 days, respectively). While these findings suggest that prehabilitation is feasible in transplant candidates and may improve posttransplantation outcomes, additional studies are needed.

POSTTRANSPLANTATION MANAGEMENT

Early postoperative activity — Early ambulation and activity should be encouraged after kidney transplant surgery. Since most kidney transplants are deceased-donor transplants that are often performed years after the initial pretransplantation evaluation, the patient's activity status and plan for returning to normal activities should also be reevaluated in the immediate posttransplantation period. (See 'Assessment of physical performance' above.)

The overwhelming majority of adult kidney transplantation surgeries are in the pelvis and not the peritoneum. Most are open surgeries with an approximately 20 to 24 cm oblique incision in the right or left lower quadrant accompanied by an incisional drain and a neocystostomy, ureteral stent, and urinary bladder catheter. Most patients are not in an intensive care unit after surgery, and the majority also have immediate kidney function, although volume overload, hemodynamic changes, and electrolyte disturbances are common. Thus, there is an opportunity for careful early activity with the hope of avoiding some postoperative complications and allowing discharge to home rather than a skilled nursing facility or inpatient rehabilitation.

Although many transplant programs have center-specific guidelines on activity, few studies have evaluated the risks and benefits of early postoperative activity and what the optimal activity is in kidney transplant recipients. In one small trial, 63 living-donor kidney transplant recipients were randomly assigned to an early physiotherapy program (120 meters of walking, breathing exercises, and steps for 30 minutes, beginning on postoperative day 1 and advancing until discharge) or standard care after transplant surgery [21]. Compared with standard care, early physiotherapy increased respiratory muscle strength at discharge without significant side effects; there was no difference in length of hospital stay.

Similarly, few studies have addressed physical activity in the postoperative three-month recovery period after kidney transplantation. An exercise trial including 30 kidney transplant patients at week 6 after surgery demonstrated improvements in six-minute walk and limb endurance at week 12 with no adverse effects noted [22].

Physical exercise — The return of significant kidney function after transplantation, by itself, does not seem to improve muscle structure, strength, or endurance [23]. Most studies have shown that the majority of kidney transplant recipients remain sedentary and do not meet various guidelines for physical activity [24]. (See 'Physical activity levels' above.)

Kidney transplant recipients should be counselled about increasing physical activity as appropriate for wound healing and comorbid conditions within the first three months of transplant surgery. Most surgeons limit physical activity that would risk wound dehiscence or hernia, such as lifting and bending, but encourage aerobic activity. We typically advise our patients to target a minimum of 7500 to 10,000 steps daily with the addition of some resistance training or exercise three times weekly. (See "Exercise prescription and guidance for adults" and "Physical activity and exercise in older adults".)

Although physical exercise have been shown to have multiple measured benefits in the general population (see "The benefits and risks of aerobic exercise", section on 'Benefits of exercise'), benefits among kidney transplant recipients have not been clearly demonstrated. Data are limited to small trials and observational studies, most of which included small study populations and had short duration of follow-up [17,25-27]. While these studies have shown various positive outcomes (such as improved quality of life and exercise capacity), there is no consensus regarding the benefits of these exercise regimens.

Potential benefits of physical activity in kidney transplant recipients have been described in small observational and/or retrospective studies and include the following [25,26]:

●Prevention of posttransplantation diabetes mellitus

●Decreased weight gain and incidence of obesity

●Decreased osteopenia

●Improvement in hypertension

●Improvement in cardiovascular disease (CVD)

●Decreased mortality

●Improved allograft function and longevity

Immunosuppression — We do not routinely adjust maintenance immunosuppression after kidney transplantation to improve physical activity. The potential myopathic side effects of glucocorticoids are well known; surprisingly, there are no data showing that glucocorticoid avoidance or withdrawal among kidney transplant recipients results in benefits to physical activity or muscle structure. One study of kidney transplant recipients (one-half of whom were on glucocorticoid-free maintenance immunosuppression) and patients undergoing hemodialysis found similar levels of physical activity, muscle strength, muscle composition, and exercise capacity between the groups [28].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Kidney transplantation".)

SUMMARY AND RECOMMENDATIONS

●General principles – Among patients with end-stage kidney disease (ESKD) who are being evaluated for kidney transplantation, preventing and managing cardiovascular disease (CVD) are major concerns, given that CVD is the leading cause of death and graft loss in this population. Physical inactivity is widely recognized as an important, modifiable risk factor for CVD among kidney transplant candidates. (See 'Introduction' above.)

●Physical activity among transplant candidates and recipients – Immediately prior to transplantation, kidney transplant candidates have lower levels of physical activity compared with healthy adult populations. After transplantation, physical activity increases but still remains lower than that seen in the general population. Physical inactivity and deconditioning among kidney transplant candidates likely result in decreased physical function and, therefore, a high burden of physical frailty and lower extremity impairment. (See 'Physical activity among transplant candidates and recipients' above.)

●Pretransplantation management

•There is no uniform consensus on whether and how to perform a functional assessment of the potential kidney transplant recipient. The optimal approach to assessing physical performance in this patient population is not known. At our centers, we routinely take a physical activity history that includes frequency, intensity, and type of activity. In patients for whom there is concern for physical debilitation, we use the six-minute walk test to assess physical function. (See 'Assessment of physical performance' above.)

•In general, regular physical activity is appropriate for most adults to maintain health and prevent CVD. In patients who are awaiting a transplant who are found to have low physical performance and activity levels during the transplant evaluation, we suggest a prehabilitation program consisting of physical therapy tailored to the needs and goals of kidney allograft recipients (Grade 2C). This physical therapy program should occur weekly for at least two months. Upon completion of the prehabilitation program, we assess the success of this intervention by repeating the six-minute walk test. (See 'Pretransplantation physical activity interventions' above.)

●Posttransplantation management

•Early ambulation and activity should be encouraged after kidney transplant surgery. Since most kidney transplants are deceased-donor transplants that are often performed years after the initial pretransplantation evaluation, the patient's activity status and plan for returning to normal activities should also be reevaluated in the immediate posttransplantation period. (See 'Early postoperative activity' above.)

•Kidney transplant recipients should be counselled about increasing physical activity as appropriate for wound healing and comorbid conditions within the first three months of transplant surgery. Most surgeons limit physical activity that would risk wound dehiscence or hernia, such as lifting and bending, but encourage aerobic activity. We typically advise our patients to target a minimum of 7500 to 10,000 steps daily with the addition of some resistance training or exercise three times weekly. (See 'Physical exercise' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Dorry Segev, MD, PhD, who contributed to an earlier version of this topic review.