Assessment of physical activity in patients with chronic kidney disease and renal replacement therapy

Physical activity and exercise in chronic kidney disease: consensus statements from the Physical Exercise Working Group of the Italian Society of Nephrology

The Italian Society of Nephrology has tasked its Working Group on Physical Exercise with developing a consensus statement document on physical activity and exercise in patients with chronic kidney disease (CKD). This paper consists of 16 points that were discussed, and approved using the mini-Delphi method by 15 members of the working group. Each statement is based on a comprehensive review of the literature, clinical experience, and expert opinions. Overall, the statements affirm that regular physical activity and exercise training offer numerous benefits to CKD patients, including improved physical function, enhanced cardiometabolic and neuromuscular function, cognitive benefits, and an overall improvement in quality of life. Furthermore, exercise may provide nephroprotection and reduce mortality. These advantages are observed across all CKD stages, whether on conservative therapy or kidney replacement therapy (hemodialysis or peritoneal dialysis), and in kidney transplant recipients. Moreover, when physical activity and exercise training are implemented with appropriate precautions, they are safe in CKD patients. Gradual physical activity and customized exercise programs should be tailored to the patient's exercise tolerance, potentially enhancing compliance. Clinicians are encouraged to use a series of questionnaires and tests to assess the patient's level of physical activity and performance. However, exercise and physical activity are poorly implemented in clinical practice due to many barriers related to patients and healthcare staff. Overcoming these barriers requires the proactive role of the nephrologists, who should actively incorporate exercise training and promote physical activity within routine care plans. Adopting a multidisciplinary team approach, which includes nephrologists, nurses, exercise professionals, and dietitians, is crucial for providing comprehensive rehabilitation for CKD patients. Integrating new technologies and remote check ups could further enhance the effectiveness of these interventions.

Home versus in-centre haemodialysis for people with kidney failure

BACKGROUND

Home haemodialysis (HHD) may be associated with important clinical, social or economic benefits. However, few randomised controlled trials (RCTs) have evaluated HHD versus in-centre HD (ICHD). The relative benefits and harms of these two HD modalities are uncertain. This is an update of a review first published in 2014. This update includes non-randomised studies of interventions (NRSIs).

OBJECTIVES

To evaluate the benefits and harms of HHD versus ICHD in adults with kidney failure.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 9 October 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov. We searched MEDLINE (OVID) and EMBASE (OVID) for NRSIs.

SELECTION CRITERIA

RCTs and NRSIs evaluating HHD (including community houses and self-care) compared to ICHD in adults with kidney failure were eligible. The outcomes of interest were cardiovascular death, all-cause death, non-fatal myocardial infarction, non-fatal stroke, all-cause hospitalisation, vascular access interventions, central venous catheter insertion/exchange, vascular access infection, parathyroidectomy, wait-listing for a kidney transplant, receipt of a kidney transplant, quality of life (QoL), symptoms related to dialysis therapy, fatigue, recovery time, cost-effectiveness, blood pressure, and left ventricular mass.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed if the studies were eligible and then extracted data. The risk of bias was assessed, and relevant outcomes were extracted. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Meta-analysis was performed on outcomes where there was sufficient data.

MAIN RESULTS

From the 1305 records identified, a single cross-over RCT and 39 NRSIs proved eligible for inclusion. These studies were of varying design (prospective cohort, retrospective cohort, cross-sectional) and involved a widely variable number of participants (small single-centre studies to international registry analyses). Studies also varied in the treatment prescription and delivery (e.g. treatment duration, frequency, dialysis machine parameters) and participant characteristics (e.g. time on dialysis). Studies often did not describe these parameters in detail. Although the risk of bias, as assessed by the Newcastle-Ottawa Scale, was generally low for most studies, within the constraints of observational study design, studies were at risk of selection bias and residual confounding. Many study outcomes were reported in ways that did not allow direct comparison or meta-analysis. It is uncertain whether HHD, compared to ICHD, may be associated with a decrease in cardiovascular death (RR 0.92, 95% CI 0.80 to 1.07; 2 NRSIs, 30,900 participants; very low certainty evidence) or all-cause death (RR 0.80, 95% CI 0.67 to 0.95; 9 NRSIs, 58,984 patients; very low certainty evidence). It is also uncertain whether HHD may be associated with a decrease in hospitalisation rate (MD -0.50 admissions per patient-year, 95% CI -0.98 to -0.02; 2 NRSIs, 834 participants; very low certainty evidence), compared with ICHD. Compared with ICHD, it is uncertain whether HHD may be associated with receipt of kidney transplantation (RR 1.28, 95% CI 1.01 to 1.63; 6 NRSIs, 10,910 participants; very low certainty evidence) and a shorter recovery time post-dialysis (MD -2.0 hours, 95% CI -2.73 to -1.28; 2 NRSIs, 348 participants; very low certainty evidence). It remains uncertain if HHD may be associated with decreased systolic blood pressure (SBP) (MD -11.71 mm Hg, 95% CI -21.11 to -2.46; 4 NRSIs, 491 participants; very low certainty evidence) and decreased left ventricular mass index (LVMI) (MD -17.74 g/m2, 95% CI -29.60 to -5.89; 2 NRSIs, 130 participants; low certainty evidence). There was insufficient data to evaluate the relative association of HHD and ICHD with fatigue or vascular access outcomes. Patient-reported outcome measures were reported using 18 different measures across 11 studies (QoL: 6 measures; mental health: 3 measures; symptoms: 1 measure; impact and view of health: 6 measures; functional ability: 2 measures). Few studies reported the same measures, which limited the ability to perform meta-analysis or compare outcomes. It is uncertain whether HHD is more cost-effective than ICHD, both in the first (SMD -1.25, 95% CI -2.13 to -0.37; 4 NRSIs, 13,809 participants; very low certainty evidence) and second year of dialysis (SMD -1.47, 95% CI -2.72 to -0.21; 4 NRSIs, 13,809 participants; very low certainty evidence).

AUTHORS' CONCLUSIONS

Based on low to very low certainty evidence, HHD, compared with ICHD, has uncertain associations or may be associated with decreased cardiovascular and all-cause death, hospitalisation rate, slower post-dialysis recovery time, and decreased SBP and LVMI. HHD has uncertain cost-effectiveness compared with ICHD in the first and second years of treatment. The majority of studies included in this review were observational and subject to potential selection bias and confounding, especially as patients treated with HHD tended to be younger with fewer comorbidities. Variation from study to study in the choice of outcomes and the way in which they were reported limited the ability to perform meta-analyses. Future research should align outcome measures and metrics with other research in the field in order to allow comparison between studies, establish outcome effects with greater certainty, and avoid research waste.

Beneficial effects of physical exercise on the osteo-renal Klotho-FGF-23 axis in Chronic Kidney Disease: A systematic review with meta-analysis

The aim of this study was to investigate the efficacy of physical exercise in chronic kidney disease, describing its impact on the Klotho-FGF23 axis. PubMed, Web of Science and Scopus databases, updated to January 2023, were searched. The present study employed mean difference and a 95% confidence interval (CI) to examine the efficacy of the intervention. Heterogeneity was assessed through inconsistency statistics (I2). Out of the 299 studies identified, a total of 4 randomized controlled trials (RCTs), comprising 272 participants, met the eligibility criteria. Compared with the control group, physical exercise significantly decreased the concentrations of FGF23 (MD: -102.07 Pg/mL, 95% CI: -176.23.47, -27.91 I2= 97%, p = 0.001), and a significantly increased the concentrations of Klotho protein: (MD: 158.82 Pg/mL, 95% CI: 123.33, -194.31, I2 = 0%, p = 0.001). The results of our study indicated that the exercise has a direct relationship with Klotho-FGF23 axis. We can conclude that physical exercise in patients with CKD produces beneficial effects on the pathophysiological components related to this disease, including cardiorespiratory fitness and vascular functions. As observed, both endurance and aerobic physical exercise increase Klotho production and decrease FGF23 levels. Evidence indicates that exercise attenuates the progression of CKD, improves uremic parameters and down-regulates inflammation-related markers.

Impact of Exercise on Fatigue in Patients Undergoing Dialysis in a Tertiary Care Hospital

Background Chronic kidney disease (CKD) is a current public health problem associated with progression to end-stage renal disease (ESRD), cardiovascular disease, and increased mortality rates. The disease is progressive. It is estimated that there are about 20-25 patients with milder kidney damage for every patient on renal replacement therapy. Physical activity is one of the critical elements for the prevention of chronic diseases and exercises in CKD help to improve muscular strength, cardiorespiratory endurance, overall function, and quality of life. Fatigue can cause an inability to perform exercises and can affect physiological and psychological function. There is a need to analyze the effects of exercises on fatigue in outpatients undergoing dialysis in the Indian rural population. Methods This study was a randomized, controlled, interventional, single-center trial. The participants diagnosed with ESRD and who were on hemodialysis were randomly assigned to group A, the exercise group (EG), which had exercise training during dialysis, and group B, the control group (CG), which had no added exercises during dialysis or at home and followed a standard routine method. The outcome measure of fatigue was evaluated through the total Fatigue Assessment Scale (FAS) score at 0, 12, 24, and 36 weeks. The exercise was pilot tested and planned based on the guidelines and carried out during hemodialysis two days a week. It was followed up with a five-day home exercise program when the patients did not undergo dialysis. Results A total of 48 participants were chosen for the study, of which 30 participants completed 36 weeks of training, with exercise adherence of more than 60%. There was a statistically significant difference in FAS between the two groups (F (3, 84) = 10.513, P < 0.001) at a 95% confidence interval (P < 0.05). Post hoc comparisons between groups at baseline and at 12 weeks indicated that there was no significant difference in FAS (P = 0.271 and P = 0.08), but recorded a significant difference (P = 0.001) at 24 and 36 weeks, respectively, between the EG and CG. Conclusions The results indicate that the intradialytic exercise intervention was effective in reducing the level of fatigue in outpatients undergoing dialysis on a long-term exercise program.

Belt Electrode-Skeletal Muscle Electrical Stimulation in Older Hemodialysis Patients with Reduced Physical Activity: A Randomized Controlled Pilot Study

Background: Although patients receiving hemodialysis are more likely to develop metabolic disorders and muscle weakness at an earlier stage than healthy individuals, many older dialysis patients have difficulty establishing exercise habits to prevent these problems. Therefore, we evaluated the use of belt electrode-skeletal muscle electrical stimulation (B-SES), which can stimulate a wider area than conventional electrical muscle stimulation (EMS), to examine its application and safety in older hemodialysis patients as a means to improve lower extremity function without voluntary effort. Methods: This study was a randomized controlled trial (RCT) involving 20 older dialysis patients (>65 years old) with reduced physical activity. The control group received 12 weeks of routine care only and the intervention group received 12 weeks of B-SES during hemodialysis in addition to routine care. The primary endpoint was the 6 min walk test (6MWT) distance, while the Short Physical Performance Battery (SPPB), body composition, Functional Independence Measure (FIM), biochemistry test, and blood pressure/pulse measurements were used as secondary endpoints. Results: As a result of the 12-week B-SES intervention, no increase in creatine kinase or C-reactive protein levels was observed after the intervention in either group, and no adverse events attributed to the B-SES intervention were observed in the intervention group. Furthermore, the intervention group showed a significant improvement in the 6MWT and SPPB scores after the intervention. Conclusions: The results of this study suggest that a 12-week B-SES intervention during hemodialysis sessions safely improves 6MWT distance and SPPB scores in older patients with a reduced level of physical activity.

Association of motivations and barriers with participation and performance in a pedometer-based intervention

BACKGROUND

A randomized trial of a pedometer-based intervention with weekly activity goals led to increased walking among dialysis patients. However, the association of participant-expressed motivations and barriers to participation and performance in such an intervention has not been determined.

METHODS

Thirty dialysis patients were randomized to a 12-week pedometer-based intervention with weekly step goals. Participants were asked about motivations and barriers to the increasing activity via weekly semi-scripted telephone interviews. We examined the association of these motivations and barriers with achieving weekly goals, reaching overall targets and increasing steps through multivariable linear and logistic regression analyses adjusted for age, sex, body mass index, dialysis modality and baseline steps.

RESULTS

The most common motivations were desire to maintain/improve functional ability (30%) and activity (30%). The most common barriers were health-related (33%). Motivation to maintain/improve functional ability was associated with achieving weekly goals 17.9% more often [95% confidence interval (CI) 1.7-34.2] and with a greater increase in steps (1524 steps; 95% CI 61-2989) than those lacking this motivation. Experiencing a health-related barrier was not associated with the decreased achievement of weekly goals but was associated with lower odds of reaching overall targets (odds ratio = 0.06; 95% CI 0.01-0.53) and a smaller increase in steps (-1640 steps, 95% CI -3244 to -36). No patients who reported weather/environmental barriers or safety concerns reached overall targets.

CONCLUSIONS

Participants who express a desire to maintain/improve functional ability may be particularly suited for activity interventions. Health-related setbacks should be met with revised goals. Reporting environmental or safety concerns may merit lowering overall targets.

The validity of the 'General Practice Physical Activity Questionnaire' against accelerometery in patients with chronic kidney disease

Background: The majority of patients with chronic kidney disease (CKD) are physically inactive. Simple yet accurate assessment of physical activity is important in identifying those in need of intervention. The 'General Practice Physical Activity Questionnaire' (GPPAQ) is a well-used clinical and research tool, but has not been validated.Methods: Forty individuals with CKD (age 62.5 (SD: 11.1) years, estimated glomerular filtration rate (eGFR) 33.2 (SD:19.1) ml/min/1.73 m²) completed the GPPAQ and objective physical activity was measured using a GENEActiv accelerometer for 7 days. Physical activity status was grouped as 'Active' (i.e. meeting current physical activity UK guidelines) or 'Inactive.' Sensitivity and specificity were calculated. Accuracy was defined as the probability the GPPAQ could correctly classify a patient as either 'Active' or 'Inactive' (based on accelerometery).Results: Using accelerometery, 18% of participants met the current UK guidelines, whereas 27% were classed as 'Active' according to GPPAQ. Sensitivity of the GPPAQ was 54.6% and specificity was 96.6%. The 'accuracy' of the GPPAQ was 85.0%. The accuracy of the GPPAQ was greater in males and those not in employment/retired, although these differences were not statistically significant.Conclusions: The GPPAQ may be a useful tool to identify CKD patients who would benefit most from a physical activity intervention. In particular, the GPPAQ can accurately identify those not sufficiently active.

Comparison of physical activity and quality of life in home haemodialysis (HHD) patients versus conventional in-centre haemodialysis (ICHD) patients: the observational, longitudinal, prospective, international, multicentric SeCoIA study protocol

BACKGROUND

Home haemodialysis (HHD), has shown improved clinical outcomes, as well as a better quality of life, compared to conventional in-centre haemodialysis (ICHD) but still has a global low prevalence among end-stage renal disease patients. Haemodialysis (HD) patients tend to be sedentary but only few studies, mainly in North American ICHD patients, have evaluated the level of activity in HD patients.

METHODS

SeCoIA is an observational, longitudinal, prospective, international, multicentric, study, conducted in metropolitan France and Belgium. The main objective of the study is to quantify the physical activity measured by the total daily number of steps, in HHD patients compared to ICHD patients. The SeCoIA study will include 80 HHD patients and 80 ICHD patients,. Secondary objectives will be to characterize the HHD population and to confirm HHD efficiency on clinical parameters, as well as quality of life (QoL), in current practice. Physical activity will be measured by a 3-axis accelerometer. Accelerometers have been shown to provide accurate information, on both physical activity and sedentary behaviour. Patients will be instructed to wear the device and complete a patient diary 7 consecutive days after inclusion and the first week of each month for 12 months. Decision to undergo HDD or ICHD is independent of the study and follow-up frequency remains at the discretion of the physician/centre. QoL and quality of sleep will be respectively assessed by the Kidney Disease Quality of Life 1.2 (KDQOL™) and the Pittsburg Sleep Quality index (PSQI) questionnaires at inclusion, 6- and 12-month visits. Patients presenting a restless leg syndrome (RLS) will also complete the International Restless Legs Syndrome rating scale (IRLS) questionnaire.

DISCUSSION

The SeCoIA study will be the first large cohort study (160 patients) evaluating physical activity, objectively measured with a 3-axis accelerometer, in HHD versus ICHD patients. The present study will also include a comparison of QoL with a focus on RLS between HHD and ICHD. It is anticipated that HHD patients will have an improved physical activity and QoL which should encourage physicians to further promote HHD.

TRIAL REGISTRATION

Clinical trial NCT03737578 study registered on November 9, 2018 (Retrospectively registered).

A Walking Intervention to Increase Weekly Steps in Dialysis Patients: A Pilot Randomized Controlled Trial

RATIONALE & OBJECTIVE

Patients receiving dialysis report very low physical activity. We implemented a pilot trial to assess the feasibility of a pedometer-based intervention to gather preliminary evidence about its impact on physical activity, symptoms, and surrogates of cardiovascular risk.

STUDY DESIGN

Pilot randomized controlled trial.

SETTING & PARTICIPANTS

60 dialysis patients from San Francisco dialysis clinics.

INTERVENTION

Participants were randomly assigned 1:1 to receiving pedometers with weekly step goals or usual care for 3 months.

OUTCOMES

The primary outcome was step counts, measured using pedometers. Secondary outcomes included physical performance using the Short Physical Performance Battery, the Physical Function and Vitality scales of the 36-Item Short Form Health Survey, the Dialysis Symptoms Index, and the Center for Epidemiologic Studies-Depression Scale, with endothelial function as a secondary and heart rate variability as an exploratory surrogate measure of cardiovascular risk. Targeted enrollment was 50% and targeted completion was 85%.

RESULTS

49% of approached patients were enrolled, and 92% completed the study. After 3 months, patients randomly assigned to the intervention (n=30) increased their average daily steps by 2,256 (95% CI, 978-3,537) more than the 30 controls (P<0.001). Heart rate variability (standard deviation of N-N intervals) increased by 14.94 (95% CI, 0.31-33.56) millisecondsin the intervention group as compared with controls (P = 0.05). There were no statistically significant differences across intervention groups in symptoms, physical performance, or endothelial function. Participants in the intervention group reverted to baseline steps during the postintervention follow-up.

LIMITATIONS

The Northern California study setting may limit generalizability. Walking does not capture the full spectrum of physical activity.

CONCLUSIONS

A short-term pedometer-based intervention led to increased step counts in dialysis patients, but the increase was not sustained. Pedometer-based interventions are feasible for dialysis patients, but future studies are needed to address whether more prolonged interventions can improve physical function or symptoms.

FUNDING

Supported by grants from the American Kidney Fund, National Institutes of Health-National Institute of Diabetes and Digestive and Kidney Diseases, and International Society of Nephrology.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study identifier NCT02623348.

Attitudes of hemodialysis patients, medical and nursing staff towards patients' physical activity

PURPOSE

Patients with end-stage renal disease (ESRD) seem to have a negative attitude towards physical activity, which is mainly favored by the lack of counseling provided by the medical and nursing staff. The aim of this study was to investigate the attitudes of both ESRD patients and medical staff on the participation and promotion of physical activity and identify the obstacles that discourage patients' involvement in intervention programs.

STUDY DESIGN

Subjective assessment questionnaires and the International Physical Activity Questionnaire were administrated to hemodialysis patients and medical staff, to investigate the association between patient's barriers to physical activity, the total intensity level of physical activity, and attitudes of both ESRD patients and medical staff on the participation and promotion of physical activity.

RESULTS

A total of 103 ESRD patients (61 men, 59.2%), 20 nephrologists (12 men, 60.0%), and 72 nurses (61 women, 84.7%) participated in the study. Most commonly reported patient's barriers were fatigue on dialysis (97.4%) and non-dialysis days (55.1%). Healthcare staff showed positive attitude towards renal rehabilitation exercise programs. However, most of physicians (85.0%) and nurses (83.3%) did not have previous experience with interventional exercise rehabilitation programs. Binary logistic regression revealed significant association between patients' inactivity, demographic data, and barriers towards physical activity, such as fatigue and pain in dialysis and non-dialysis days (p < 0.05), family's and physician's concern (p < 0.05), too many medical problems (p < 0.05), the fear of getting hurt (p = 0.01), and unwillingness for exercise (p < 0.05). Interestingly, healthcare staff's negative attitudes toward patient's physical activity seem to be strongly associated with patient's inactivity status.

CONCLUSION

Healthcare staff negative attitudes and multiple related barriers especially fatigue on dialysis and non-dialysis days, towards ESRD patient's physical activity, suppress desire for exercise and active patients' status, leading them to abstain from it.

Relationships between illness representations, physical activity and depression in chronic kidney disease

BACKGROUND

Chronic Kidney Disease (CKD) is exacerbated by depression and confers significant healthcare costs. Whilst adverse impacts may be mitigated by physical activity, many patients with CKD remain physically inactive, with this physical inactivity potentially influenced by how CKD is appraised.

OBJECTIVES

The study aims to explore the relationship between physical activity, depression and illness representations in CKD.

METHODS

Patients with CKD but not requiring dialysis completed the Revised Illness Perception Questionnaire (IPQ-R), Beck Depression Inventory (BDI-II) and Short-Form International Physical Activity Questionnaire (IPAQ-SF). Demographic information was obtained via medical records. Correlation and regression analyses were conducted to determine the relationship of illness representations with levels of physical activity. Moderation and mediation analyses were performed to investigate the role of depression in any relationship between illness representations and physical activity levels.

RESULTS

Seventy respondents, 60 % male, with a mean age of 60 ± 16 years, took part in the study. Of illness representation dimensions, personal control was positively associated with levels of physical activity whilst timeline cyclical (a subscale of the IPQ-R relating to patient beliefs about the nature of their illness) was a significant predictor. Severity of depression was neither a moderator nor a mediator of illness representations and levels of physical activity.

CONCLUSION

Facets of illness representations had significant relationships with levels of physical activity. Future research concerning the development and validation of psychological interventions based on an illness representations framework for patients with CKD not requiring dialysis is proposed. The efficacy of such interventions could be then evaluated using a randomised controlled method.

Association of self-reported physical function with survival in patients with chronic kidney disease

Background

Reduced physical function is associated with an increased risk of mortality among patients with chronic kidney disease (CKD) not requiring renal replacement therapy (RRT). Assessments of physical performance can help to identify those at risk for adverse events. However, objective measures are not always feasible and self-reported measures may provide a suitable surrogate.

Methods

We performed a cohort study examining associations between self-reported physical function and walking behaviour with survival in patients with CKD not requiring RRT. Data were analysed from the QCKD study (Physical activity opinions in kidney disease) (ISRCTN 87066351), a prospective observational mixed methods study of physical activity in patients with CKD. A total of 450 patients with CKD not requiring RRT, ages 17–93 years, were followed up for a median of 43 months. Upon enrolment, participants completed two questionnaires: Duke Activity Status Index (DASI) (physical function) and General Practice Physical Activity Questionnaire (GPPAQ) (habitual activity). Mortality data were collected from electronic records in September 2016; RRT was considered a competing event.

Results

A total of 74 deaths occurred during follow-up and 101 participants were started on RRT. The adjusted subdistribution hazard ratio (SHR) of mortality in participants scoring >19.2 on the DASI was 0.51 [95% confidence interval (CI) 0.30–0.88] while a one-unit increase in the DASI was associated with an SHR of 0.97 (95% CI 0.95–0.99). The adjusted SHRs of mortality were 0.48 (95% CI 0.26–0.90), 0.25 (0.11–0.57) and 0.48 (0.23–0.80) for participants walking <1, 1–3 and ≥3 h/week, respectively, compared with no walking. A walking pace >3 mph was associated with a reduced risk of mortality [SHR 0.37 (95% CI 0.20–0.71)] compared with a walking pace <3 mph.

Conclusions

Physical function and walking behaviours were independently associated with survival in CKD and may help to identify patients at risk for adverse events.

Dysregulated Handling of Dietary Protein and Muscle Protein Synthesis After Mixed-Meal Ingestion in Maintenance Hemodialysis Patients

Introduction

Skeletal muscle loss is common in patients with renal failure who receive maintenance hemodialysis (MHD) therapy. Regular ingestion of protein-rich meals are recommended to help offset muscle protein loss in MHD patients, but little is known about the anabolic potential of this strategy.

Methods

Eight MHD patients (age: 56 ± 5 years; body mass index [BMI]: 32 ± 2 kg/m²) and 8 nonuremic control subjects (age: 50 ± 2 years: BMI: 31 ± 1 kg/m²) received primed continuous L-[ring-²H₅]phenylalanine and L-[1-¹³C]leucine infusions with blood and muscle biopsy sampling on a nondialysis day. Participants consumed a mixed meal (546 kcal; 20-g protein, 59-g carbohydrates, 26-g fat) with protein provided as L-[5,5,5-²H₃]leucine-labeled eggs.

Results

Circulating dietary amino acid availability was reduced in MHD patients (41 ± 5%) versus control subjects (61 ± 4%; P = 0.03). Basal muscle caspase-3 protein content was elevated (P = 0.03) and large neutral amino acid transporter 1 (LAT1) protein content was reduced (P = 0.02) in MHD patients versus control subjects. Basal muscle protein synthesis (MPS) was ∼2-fold higher in MHD patients (0.030 ± 0.005%/h) versus control subjects (0.014 ± 0.003%/h) (P = 0.01). Meal ingestion failed to increase MPS in MHD patients (absolute change from basal: 0.0003 ± 0.007%/h), but stimulated MPS in control subjects (0.009 ± 0.002%/h; P = 0.004).

Conclusions

MHD patients demonstrated muscle anabolic resistance to meal ingestion. This blunted postprandial MPS response in MHD patients might be related to high basal MPS, which results in a stimulatory ceiling effect and/or reduced plasma dietary amino acid availability after mixed-meal ingestion.

Physical Activity in Kidney Transplant Recipients: A Review

Physical activity has known health benefits and is associated with reduced cardiovascular risk in the general population. Relatively few data are available for physical activity in kidney transplant recipients. Compared to the general population, physical activity levels are lower overall in kidney recipients, although somewhat higher compared to the dialysis population. Recipient comorbid condition, psychosocial and socioeconomic factors, and long-term immunosuppression use negatively affect physical activity. Physical inactivity in kidney recipients may be associated with reduced quality of life, as well as increased mortality. Interventions such as exercise training appear to be safe in kidney transplant recipients and are associated with improved quality of life and exercise capacity. Additional studies are required to evaluate long-term effects on cardiovascular risk factors and ultimately cardiovascular disease outcomes and patient survival. Currently available data are characterized by wide variability in the interventions and outcome measures investigated in studies, as well as use of small sample-sized cohorts. These limitations highlight the need for larger studies using objective and standardized measures of physical activity and physical fitness in kidney transplant recipients.

Barriers to exercise for patients with renal disease: an integrative review

Renal disease is a common health condition that leads to loss of physical function, frailty, and premature loss of independence in addition to other severe comorbidities and increased mortality. Increased levels of physical activity and initiation of exercise training is recommended in the current guidelines for all patients with renal disease, but participation and adherence rates are low. The barriers to exercise and physical activity in patients with renal disease are not well defined and currently based on patient provider perception and opinion. There have been no published reviews that have synthesized published findings on patient reported barriers to exercise. This integrative literature review therefore aimed to identify the current understanding of patient reported barriers to regular exercise. This integrative review found that patient perceived barriers to exercise are not consistent with the barriers that have been identified by renal disease specialists and healthcare providers, which were disinterest, lack of motivation, and being incapable of exercise. The patient reported barriers identified through this review were complex and diverse, and the most frequently reported patient perceived barrier to exercise was low energy levels and fatigue. It is clear that additional research to identify patient perceived barriers to exercise is needed and that patient directed interventions to address these barriers should be developed. This integrative review provides information to the interdisciplinary nephrology team that can be used to tailor their assessment of barriers to exercise and provide exercise education for patients with renal disease.

Prehabilitation for the Frail Patient Approaching ESRD

Frailty is a distinct phenotype that is highly prevalent in chronic kidney disease (CKD) and appears to be more prevalent with decreasing glomerular filtration rate. Exercise training or intervention to increase physical activity may ameliorate poor physical functioning and frailty, and even may improve survival in patients with CKD. Although exercise interventions improve outcomes across the spectrum of CKD, including patients treated with dialysis, patients treated with dialysis face barriers to exercise that patients with predialysis CKD do not. Rehabilitation at earlier stages of CKD (or prehabilitation before dialysis) might be more beneficial than not addressing the decreasing physical functioning and low physical activity until patients are receiving dialysis. This review summarizes available literature on frailty in the CKD and end-stage renal disease population, including exercise interventions and the limited evidence for prehabilitation as a strategy.

Erratum to: Assessment of physical activity in patients with chronic kidney disease and renal replacement therapy

[This corrects the article DOI: 10.1186/s40064-015-1338-3.].