Intradialytic exercise as anabolic therapy in haemodialysis patients - a pilot study

Measurement properties of performance-based measures to assess physical function in chronic kidney disease: recommendations from a COSMIN systematic review

Background

There is wide heterogeneity in physical function tests available for clinical and research use, hindering our ability to synthesize evidence. The aim of this review was to identify and evaluate physical function measures that could be recommended for standardized use in chronic kidney disease (CKD).

Methods

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, CINAHL, Scopus and Web of Science were searched from inception to March 2022, identifying studies that evaluated a clinimetric property (validity, reliability, measurement error and/or responsiveness) of an objectively measured performance-based physical function outcomes using the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) methodology and Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) based recommendations. Studies with individuals of all ages and of any stage of CKD were included.

Results

In total, 50 studies with 21 315 participants were included. Clinimetric properties were reported for 22 different physical function tests. The short physical performance battery (SPPB), Timed-up-and-go (TUG) test and Sit-to-stand tests (STS-5 and STS-60) had favorable properties to support their use in CKD and should be integrated into routine use. However, the majority of studies were conducted in the hemodialysis population, and very few provided information regarding validity or reliability.

Conclusion

The SPPB demonstrated the highest quality of evidence for reliability, measurement error and construct validity amongst transplant, CKD and dialysis patients. This review is an important step towards standardizing a core outcome set of tools to measure physical function in research and clinical settings for the CKD population.

Seven months of aerobic intradialytic exercise training can prevent muscle loss in haemodialysis patients: an ultrasonography study

PURPOSE

This study aimed to evaluate the effects of 7-month intradialytic exercise training (IDE) on vastus lateralis (VL) muscle architecture, functional capacity and quality of life in stable haemodialysis (HD) patients.

METHODS

44 HD patients were randomly assigned into an Exercise Group (EG = 21), which they received 7 months of IET, at 60% of pre-assessed maximum aerobic power, 3/week) or into a Control Group (CG = 23, no exercise). VL architecture was evaluated with ultrasonography, functional capacity was assessed using a series of functional tests (6 min walking test, 5 repetitions sit-to-stand, sit-to-stand 60 s, handgrip strength), and maximal aerobic power determined with a modified version of the Åstrand test. Quality of life and fatigue levels were evaluated using validated questionnaires.

RESULTS

VL fascicle angle and length did not change significantly in both groups (P > 0.05). Muscle thickness decreased in CG (P = 0.02) while it was fully preserved in the EG. Functional capacity increased only in the EG (6 min walking test 15.79 ± 12.35%, P < 0.001; max aerobic power 26.36 ± 1.24%, P < 0.001; STS-60rep: 10.23 ± 1.60%, P < 0.000; hand grip strength: 5.14 ± 28.30%, P < 0.02).

CONCLUSION

Intradialytic aerobic exercise training, improves functional capacity and prevents thigh muscle mass loss in HD patients. It is evident that muscle ultrasonography could play a pivotal role in assessing muscle quality changes in haemodialysis patients. A higher level of training intensity or combination with resistance exercises may be required to further improve anabolism and influence muscle architecture in this patient population.

CLINICAL TRIAL REGISTRY NUMBER

NCT03905551.

Estimating of Residual Kidney Function by Multi-Frequency Bioelectrical Impedance Analysis in Hemodialysis Patients Without Urine Collection

BACKGROUND/AIMS

Residual kidney function (RKF) is a pivotal predictor of better clinical outcomes in maintenance hemodialysis (MHD) patients. So far there has been no attempt to use bioimpedance analysis (BIA) measurements to calculate residual glomerular filtration rate (GFR) in dialysis population. We hypothesized that performing of multi-frequency BIA at the beginning and end of hemodialysis session can enable us to predict the measured residual GFR in MHD patients. Thus our aim was to develop and validate a new RKF prediction equation using multi-frequency BIA in MHD patients.

METHODS

It was diagnostic test evaluation study in a prospective cohort. Participants (n=88; mean age, 66.3±13.2 years, 59.1% males) were recruited from a single hemodialysis center. A new equation (eGFRBIA) to predict RKF, utilizing BIA measurements performed pre- and post-dialysis, was generated and cross-validated by the leave-one-out procedure. GFR estimated as the mean of urea and creatinine clearance (mGFR) using urine collections during entire interdialytic period.

RESULTS

A prediction equation for mGFR that includes both pre- and post-dialysis BIA measurements provided a better estimate than either pre- or post-dialysis measurements alone. Mean bias between predicted and measured GFR was -0.12 ml/min. Passing and Bablok regression showed no bias and no significant deviation in linearity. Concordance correlation coefficient indicated good agreement between the eGFRBIA and mGFR (0.75, P<0.001). Using cut-off predicted mGFR levels >2 ml/min/1.73 m2 yielded an area under curve of 0.96, sensitivity 85%, and specificity 89% in predicting mGFR. The κ scores for intraobserver reproducibility were consistent with substantial agreement between first and second estimation of RKF according to eGFRBIA (weighted κ was 0.60 [0.37-0.83]).

CONCLUSION

We present a valid and clinically obtainable method to predict RKF in MHD patients. This method, which uses BIA, may prove as accurate, convenient and easily reproducible while it is operator independent.

Anabolic exercise in haemodialysis patients: a randomised controlled pilot study

BACKGROUND

The anabolic response to progressive resistance exercise training (PRET) in haemodialysis patients is unclear. This pilot efficacy study aimed to determine whether high-intensity intradialytic PRET could reverse atrophy and consequently improve strength and physical function in haemodialysis patients. A second aim was to compare any anabolic response to that of healthy participants completing the same program.

METHODS

In a single blind controlled study, 23 haemodialysis patients and 9 healthy individuals were randomly allocated to PRET or an attention control (SHAM) group. PRET completed high-intensity exercise leg extensions using novel equipment. SHAM completed low-intensity lower body stretching activities using ultra light resistance bands. Exercises were completed thrice weekly for 12 weeks, during dialysis in the haemodialysis patients. Outcomes included knee extensor muscle volume by magnetic resonance imaging, knee extensor strength by isometric dynamometer and lower body tests of physical function. Data were analysed by a per protocol method using between-group comparisons.

RESULTS

PRET elicited a statistically and clinically significant anabolic response in haemodialysis patients (PRET-SHAM, mean difference [95 % CI]: 193[63 to 324] cm(3)) that was very similar to the response in healthy participants (PRET-SHAM, 169[-41 to 379] cm(3)). PRET increased strength in both haemodialysis patients and healthy participants. In contrast, PRET only enhanced lower body functional capacity in the healthy participants.

CONCLUSIONS

Intradialytic PRET elicited a normal anabolic and strength response in haemodialysis patients. The lack of a change in functional capacity was surprising and warrants further investigation.

The impact of an exercise physiologist coordinated resistance exercise program on the physical function of people receiving hemodialysis: a stepped wedge randomised control study

Background

Exercise during hemodialysis treatments improves physical function, markers of cardiovascular disease and quality of life. However, exercise programs are not a part of standard therapy in the vast majority of hemodialysis clinics internationally. Hemodialysis unit-based accredited exercise physiologists may contribute to an increased intradialytic exercise uptake and improved physical function.

Methods and design

This is a stepped wedge cluster randomised controlled trial design. A total of 180 participants will be recruited from 15 community satellite hemodialysis clinics in a large metropolitan Australian city. Each clinic will represent a cluster unit. The stepped wedge design will consist of three groups each containing five randomly allocated cluster units, allocated to either 12, 24 or 36 weeks of the intervention. The intervention will consist of an accredited exercise physiologist-coordinated program consisting of six lower body resistance exercises using resistance elastic bands and tubing. The resistance exercises will include leg abduction, plantar flexion, dorsi flexion, straight-leg/bent-knee raise, knee extension and knee flexion. The resistance training will incorporate the principle of progressive overload and completed in a seated position during the first hour of hemodialysis treatment. The primary outcome measure is objective physical function measured by the 30-second sit to stand test. Secondary outcome measures include the 8-foot timed-up-and-go test, the four square step test, quality of life, cost-utility analysis, uptake and involvement in community activity, self-reported falls, fall’s confidence, medication use, blood pressure and morbidity (hospital admissions).

Discussion

The results of this study are expected to determine the efficacy of an accredited exercise physiologist supervised resistance training on the physical function of people receiving hemodialysis and the cost-utility of exercise physiologists in hemodialysis centres. This may contribute to intradialytic exercise as standard therapy using an exercise physiologist workforce model.

Trial registration

Current Controlled Trials ACTRN12612001223820.

Patients' perspectives on the implementation of intra-dialytic cycling--a phenomenographic study

BACKGROUND

Adults undergoing haemodialysis have significantly reduced physical capacity and run a high risk of developing cardiovascular complications. Research has shown that intra-dialytic cycling has many evidence-based health effects, but implementation is rare within renal clinical practice. This may be due to several causes, and this study focuses on the patients' perspective. This perspective has seldom been taken into account when aiming to assess and improve the implementation of clinical research. The aim of this study was to describe how adults undergoing in-centre haemodialysis treatment experienced an implementation process of intra-dialytic cycling. It aimed to identify potential motivators and barriers to the implementation process from a patient perspective.

METHODS

Maximum-variation purposive sampling was used. Data were collected until saturation, through semistructured interviews, which were analysed using phenomenography.

RESULTS

The implementation of intra-dialytic cycling was experienced as positive, as it had beneficial effects on physical and psychological well-being. It was easy to perform and did not intrude on patients' spare time. These factors increased the acceptance of the implementation and supported the maintenance of intra-dialytic cycling as an evidence-based routine within their haemodialysis care. The patients did, however, experience some barriers to accepting the implementation of intra-dialytic cycling. These barriers were sometimes so strong that they outweighed the participants' knowledge of the advantages of intra-dialytic cycling and the research evidence of its benefits. The barriers sometimes also outweighed the participants' own wish to cycle. The barriers that we identified concerned not only the patients but also the work situation of the haemodialysis nurses.

CONCLUSIONS

Consideration of the motivators and barriers that we have identified can be used in direct care to improve the implementation of intra-dialytic cycling.

Exercise training for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health problem. In the National Kidney Foundation Disease Outcomes Quality Initiative guidelines it is stressed that lifestyle issues such as physical activity should be seen as cornerstones of the therapy. The physical fitness in adults with CKD is so reduced that it impinges on ability and capacity to perform activities in everyday life and occupational tasks. An increasing number of studies have been published regarding health effects of various regular exercise programmes in adults with CKD and in renal transplant patients.

OBJECTIVES

We aimed to: 1) assess the effects of regular exercise in adults with CKD and kidney transplant patients; and 2) determine how the exercise programme should be designed (e.g. type, duration, intensity, frequency of exercise) to be able to affect physical fitness and functioning, level of physical activity, cardiovascular dimensions, nutrition, lipids, glucose metabolism, systemic inflammation, muscle morphology and morphometrics, dropout rates, compliance, adverse events and mortality.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, CENTRAL, MEDLINE, EMBASE, CINAHL, Web of Science, Biosis, Pedro, Amed, AgeLine, PsycINFO and KoreaMed. We also handsearched reference lists of review articles and included studies, conference proceeding's abstracts. There were no language restrictions.Date of last search: May 2010.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) enrolling adults with CKD or kidney transplant recipients undergoing any type of physical exercise intervention undertaken for eight weeks or more. Studies using less than eight weeks exercise, those only recommending an increase in physical activity, and studies in which co-interventions are not applied or given to both groups were excluded.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of study and data quality were performed independently by the two authors. Continuous outcome data are presented as standardised mean difference (SMD) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Forty-five studies, randomising 1863 participants were included in this review. Thirty two studies presented data that could be meta-analysed. Types of exercise training included cardiovascular training, mixed cardiovascular and resistance training, resistance-only training and yoga. Some studies used supervised exercise interventions and others used unsupervised interventions. Exercise intensity was classed as 'high' or 'low', duration of individual exercise sessions ranged from 20 minutes/session to 110 minutes/session, and study duration was from two to 18 months. Seventeen per cent of studies were classed as having an overall low risk of bias, 33% as moderate, and 49% as having a high risk of bias.The results shows that regular exercise significantly improved: 1) physical fitness (aerobic capacity, 24 studies, 847 participants: SMD -0.56, 95% CI -0.70 to -0.42; walking capacity, 7 studies, 191 participants: SMD -0.36, 95% CI-0.65 to -0.06); 2) cardiovascular dimensions (resting diastolic blood pressure, 11 studies, 419 participants: MD 2.32 mm Hg, 95% CI 0.59 to 4.05; resting systolic blood pressure, 9 studies, 347 participants: MD 6.08 mm Hg, 95% CI 2.15 to 10.12; heart rate, 11 studies, 229 participants: MD 6 bpm, 95% CI 10 to 2); 3) some nutritional parameters (albumin, 3 studies, 111 participants: MD -2.28 g/L, 95% CI -4.25 to -0.32; pre-albumin, 3 studies, 111 participants: MD - 44.02 mg/L, 95% CI -71.52 to -16.53; energy intake, 4 studies, 97 participants: SMD -0.47, 95% CI -0.88 to -0.05); and 4) health-related quality of life. Results also showed how exercise should be designed in order to optimise the effect. Other outcomes had insufficient evidence.

AUTHORS' CONCLUSIONS

There is evidence for significant beneficial effects of regular exercise on physical fitness, walking capacity, cardiovascular dimensions (e.g. blood pressure and heart rate), health-related quality of life and some nutritional parameters in adults with CKD. Other outcomes had insufficient evidence due to the lack of data from RCTs. The design of the exercise intervention causes difference in effect size and should be considered when prescribing exercise with the aim of affecting a certain outcome. Future RCTs should focus more on the effects of resistance training interventions or mixed cardiovascular- and resistance training as these exercise types have not been studied as much as cardiovascular exercise.

Intradialytic exercise programs for hemodialysis patients

Although it is widely accepted that exercise is beneficial in patients with end-stage renal disease as in the general population, it is not easy to incorporate exercise programs into routine clinical practice. This review aimed to investigate the beneficial effects of exercise during hemodialysis and also to introduce various intradialytic exercise programs and their advantages as a first step in combining exercise programs into clinical practice. Aerobic and resistance exercise are beneficial not only in improving physical functioning, including maximal oxygen uptake and muscle strength, but also in improving anthropometrics, nutritional status, hematological indexes, inflammatory cytokines, depression, and health-related quality of life. However, it is not clear whether the beneficial effects of exercise are limited to only relatively healthy dialysis patients. Therefore, the effects of individualized exercise programs for elderly patients or patients with comorbid conditions need to be studied further.

Test-retest reliability and minimal detectable change scores for sit-to-stand-to-sit tests, the six-minute walk test, the one-leg heel-rise test, and handgrip strength in people undergoing hemodialysis

BACKGROUND

Determining the relative and absolute reliability of outcomes of physical performance tests for people undergoing hemodialysis is necessary to discriminate between the true effects of exercise interventions and the inherent variability of this cohort.

OBJECTIVE

The aims of this study were to assess the relative reliability of sit-to-stand-to-sit tests (the STS-10, which measures the time [in seconds] required to complete 10 full stands from a sitting position, and the STS-60, which measures the number of repetitions achieved in 60 seconds), the Six-Minute Walk Test (6MWT), the one-leg heel-rise test, and the handgrip strength test and to calculate minimal detectable change (MDC) scores in people undergoing hemodialysis.

DESIGN

This study was a prospective, nonexperimental investigation.

METHODS

Thirty-nine people undergoing hemodialysis at 2 clinics in Spain were contacted. Study participants performed the STS-10 (n=37), the STS-60 (n=37), and the 6MWT (n=36). At one of the settings, the participants also performed the one-leg heel-rise test (n=21) and the handgrip strength test (n=12) on both the right and the left sides. Participants attended 2 testing sessions 1 to 2 weeks apart.

RESULTS

High intraclass correlation coefficients (≥.88) were found for all tests, suggesting good relative reliability. The MDC scores at 90% confidence intervals were as follows: 8.4 seconds for the STS-10, 4 repetitions for the STS-60, 66.3 m for the 6MWT, 3.4 kg for handgrip strength (force-generating capacity), 3.7 repetitions for the one-leg heel-rise test with the right leg, and 5.2 repetitions for the one-leg heel-rise test with the left leg. Limitations A limited sample of patients was used in this study.

CONCLUSIONS

The STS-16, STS-60, 6MWT, one-leg heel rise test, and handgrip strength test are reliable outcome measures. The MDC scores at 90% confidence intervals for these tests will help to determine whether a change is due to error or to an intervention.

Sustaining a hemodialysis exercise program: a review

This article reviews the literature addressing exercise programs for dialysis patients to identify elements necessary for sustaining exercise programs in this population. Literature searches for publications (January 1980-February 2009) in Medline (OVID), PubMed, CINAHL (EBSCO), EBSCOhost EJS, ProQuest Central, Web of Science, Cochrane Library, Google Scholar, ScienceDirect, SpringerLink (Kluwer), and Wiley Interscience (Blackwell) were performed. Reference lists from relevant articles were hand-searched for further publications. Criteria for inclusion included full-text primary research and review articles focused on exercise for adult hemodialysis patients. One hundred and seventy one publications were found with a primary focus on exercise in hemodialysis. Of these, 28 primary research and 14 review articles addressed one or more aspects of sustainability of hemodialysis exercise programs. Factors contributing to sustainable exercise programs included: dedicated exercise professionals; encouragement to exercise intradialytically; dialysis and medical staff commitment; adequate physical requirements of equipment and space; interesting and stimulating; cost implications need to be addressed; exercise is not for everyone; requires individual prescription; and there is no age barrier to exercise on hemodialysis.

Effects of high-intensity resistance training in patients with rheumatoid arthritis: a randomized controlled trial

OBJECTIVE

To confirm, in a randomized controlled trial (RCT), the efficacy of high-intensity progressive resistance training (PRT) in restoring muscle mass and function in patients with rheumatoid arthritis (RA). Additionally, to investigate the role of the insulin-like growth factor (IGF) system in exercise-induced muscle hypertrophy in the context of RA.

METHODS

Twenty-eight patients with established, controlled RA were randomized to either 24 weeks of twice-weekly PRT (n = 13) or a range of movement home exercise control group (n = 15). Dual x-ray absorptiometry-assessed body composition (including lean body mass [LBM], appendicular lean mass [ALM], and fat mass); objective physical function; disease activity; and muscle IGFs were assessed at weeks 0 and 24.

RESULTS

Analyses of variance revealed that PRT increased LBM and ALM (P < 0.01); reduced trunk fat mass by 2.5 kg (not significant); and improved training-specific strength by 119%, chair stands by 30%, knee extensor strength by 25%, arm curls by 23%, and walk time by 17% (for objective function tests, P values ranged from 0.027 to 0.001 versus controls). In contrast, body composition and physical function remained unchanged in control patients. Changes in LBM and regional lean mass were associated with changes in objective function (P values ranged from 0.126 to <0.0001). Coinciding with muscle hypertrophy, previously diminished muscle levels of IGF-1 and IGF binding protein 3 both increased following PRT (P < 0.05).

CONCLUSION

In an RCT, 24 weeks of PRT proved safe and effective in restoring lean mass and function in patients with RA. Muscle hypertrophy coincided with significant elevations of attenuated muscle IGF levels, revealing a possible contributory mechanism for rheumatoid cachexia. PRT should feature in disease management.

Exercise performance by hemodialysis patients: a review of the literature

Hemodialysis (HD) patients exhibit poor functional capacity and reduced quality of life as a result of the complications associated with end-stage renal disease (ESRD). A review of the literature indicates that regular physical activity can reduce the complications associated with ESRD by inducing adaptations in the cardiovascular, nervous, and musculoskeletal systems. In turn, this increases functional capacity and enhances quality of life in patients on HD. Hemodialysis patients can safely participate in a variety of exercise programs with minimal adverse effects. Intradialytic exercise programs that can incorporate aerobic and resistance exercise promote exercise adherence and should be encouraged on dialysis units.

Anabolic interventions in ESRD

ESRD produces a chronic catabolic state that results in significant skeletal muscle atrophy, weakness, and physical dysfunction. Any intervention that can ameliorate this process can significantly improve quality of life. Some studies have shown that endurance exercise training, even at low intensities, may exhibit anabolic effects and improved physical function. However, resistance exercise training is of primary interest as an anabolic intervention because it is the mode of exercise that is most efficacious in stimulating anabolic responses, improved muscle performance, and physical function. A relatively small number of controlled trials of resistance training in ESRD patients have failed to show significant changes in LBM, although some studies have shown significant improvements in other markers of anabolism. Increases in muscle strength with resistance training are typical but improved physical function, either by objective measurement or self-report, are equivocal. Study durations, loads used during training, and relatively small sample sizes may in part explain the inability of previous studies to observe more substantial changes in LBM and physical function. Androgens and growth hormone have been shown to significantly improve LBM and strength, although longer-term studies for safety and efficacy are necessary before their general recommendation for patients with ESRD.

Segurança e eficácia do treinamento físico na insuficiência renal crônica

A doença renal crônica acarreta alterações em todos os sistemas corporais. Os pacientes cursam com marcada redução do condicionamento cardiorrespiratório, alterações musculares, reduzida performance física e pior qualidade de vida. A atividade física tem sido cada vez mais utilizada como forma de tratamento para essa população. Programas de treinamento físico aeróbio e/ou resistidos de moderada ou baixa intensidade no período interdialítico e durante a hemodiálise têm sido utilizados. Entretanto, os benefícios dessas intervenções no doente renal crônico, a escolha mais apropriada do tipo de treinamento e a segurança da aplicabilidade de atividades específicas não estão bem esclarecidos. Esta revisão tem como objetivo abordar os aspectos relacionados com o tipo de treinamento, período em que este é realizado, assim como os possíveis benefícios que o treinamento físico pode induzir nessa população.

Review article: Tackling the survival issue in end-stage renal disease: time to get physical on haemodialysis

Life expectancy in haemodialysis patients is reduced fourfold on average versus healthy age-matched individuals. The purpose of this review is to present empirical evidence that intradialytic exercise can mitigate primary independent risk factors for early mortality in end-stage renal disease. These risk factors include measures of skeletal muscle wasting, systemic inflammation, cardiovascular functioning and dialysis adequacy. Overall, the available literature provides support for the integration of exercise within the conventional outpatient haemodialysis unit. The amelioration of various physiological risk factors through an appropriate exercise prescription may enhance survival in this vulnerable cohort. Investigations are required to determine the effects of various doses of intradialytic exercise on a broad range of clinical outcomes, and more thoroughly elucidate the relationship between exercise-induced adaptations and survival advantage in end-stage renal disease.

How can exercise be incorporated into the routine care of patients on dialysis?

Regular physical activity and exercise can have many beneficial effects for dialysis patients. The provision of an opportunity for patients to exercise at their treatment center has several advantages, but almost any method of increasing activity is likely to be beneficial. In addition to in-center programs such as cycling exercise before or during dialysis, other exercise options include participation in community-based walking programs, water exercise or swimming, yoga, Tai Chi, or low-level strengthening programs. Physical therapy that is individualized to meet patients' needs is also especially appropriate for older persons. The essential condition is that the unit and staff are committed to a treatment culture that makes physical activity a priority. Asking patients what they are doing for regular exercise should be part of routine patient assessment.

A comparison of aerobic exercise and resistance training in patients with and without chronic kidney disease

The morbidity and mortality associated with chronic kidney disease (CKD) are primarily caused by atherosclerosis and cardiovascular disease, which may be in part caused by inflammation and oxidative stress. Aerobic exercise and resistance training have been proposed as measures to combat obesity, inflammation, endothelial dysfunction, oxidative stress, insulin resistance, and progression of CKD. In non-CKD patients, aerobic exercise reduces inflammation, increases insulin sensitivity, decreases microalbuminuria, facilitates weight loss, decreases leptins, and protects against oxidative injury. In nondialysis CKD, aerobic exercise decreases microalbuminuria, protects from oxidative stress, and may increase the glomerular filtration rate (GFR). Aerobic exercise in hemodialysis patients has been reported to enhance insulin sensitivity, improve lipid profile, increase hemoglobin, increase strength, decrease blood pressure, and improve quality of life. Resistance training, in the general population, decreases C-reactive protein, increases insulin sensitivity, decreases body fat content, increases insulin-like growth factor-1 (IGF-1), and decreases microalbuminuria. In the nondialysis CKD population, resistance training has been reported to reduce inflammation, increase serum albumin, maintain body weight, increase muscle strength, increase IGF-1, and increase GFR. Resistance training in hemodialysis increases muscle strength, increases physical functionality, and improves IGF-1 status. Combined aerobic exercise and resistance training during dialysis improves muscle strength, work output, cardiac fitness, and possibly dialysis adequacy. There is a need for more investigation on the role of exercise in CKD. If the benefits of aerobic exercise and strength training in non-CKD populations can be shown to apply to CKD patients as well, renal rehabilitation will begin to play an important role in the approach to the treatment, prevention, and slowed progression of CKD.

Randomized Controlled Trial of Intradialytic Resistance Training to Target Muscle Wasting in ESRD: The Progressive Exercise for Anabolism in Kidney Disease (PEAK) Study

BACKGROUND

To determine whether prolonged (24 weeks) intradialytic progressive resistance training (PRT) could counteract muscle wasting more effectively than short-duration training (12 weeks) in patients with end-stage renal disease.

STUDY DESIGN

Randomized controlled trial.

SETTING & PARTICIPANTS

49 patients (age, 62.6 +/- 14.2 years; 0.3 to 16.7 years on hemodialysis therapy) were randomly assigned to PRT plus usual care for 24 weeks (24WK group) or a crossover control group that received usual care for the first 12 weeks, then PRT plus usual care for the latter 12 weeks (12WK group).

INTERVENTION

Two sets of 10 free-weight PRT exercises were performed at a high intensity during routine thrice-weekly hemodialysis treatment under direct supervision.

OUTCOMES & MEASUREMENTS

Primary outcomes include thigh muscle cross-sectional area by means of computed tomography and intramuscular lipid content estimated through attenuation. Secondary outcomes include muscular strength, exercise capacity, and C-reactive protein level.

RESULTS

The 24WK group increased muscle cross-sectional area (+1.82 +/- 3.25 cm(2)) compared with losses in the 12WK group (-1.37 +/- 6.87 cm(2); relative effect size, 0.59; 95% confidence interval [CI], -0.27 to 6.65; P = 0.04). However, this outcome did not achieve the level of statistical significance required (P = 0.025) after Bonferroni correction for multiple primary outcomes. There was no significant change in intramuscular lipid content between groups (+0.19 +/- 1.32 versus +0.16 +/- 1.69 Hounsfield units in the 24WK and 12WK groups, respectively; P = 0.31). Log C-reactive protein level tended to decrease in the 24WK group compared with the 12WK group (relative effect size, -0.63; 95% CI, -0.27 [-0.54 to 0.00]; P = 0.05). The 24WK group improved muscular strength measures and exercise capacity throughout the trial.

LIMITATIONS

Single geographic site used; no control group without exercise exposure; unblinded assessment of some secondary outcome measures.

CONCLUSIONS

Prolonged intradialytic PRT did not significantly improve muscle cross-sectional area or intramuscular lipid content compared with a shorter duration of exercise. Future trials are required to more thoroughly investigate the clinical importance and magnitude of myogenic adaptations to PRT in this cohort.

The functional, metabolic, and anabolic responses to exercise training in renal transplant and hemodialysis patients

BACKGROUND

Exercise intolerance is common in hemodialysis (HD) and renal transplant (RTx) patients and is related to muscle weakness. Its pathogenesis may vary between these groups leading to a different response to exercise. The aim of the study was to compare intrinsic muscular parameters between HD and RTx patients and controls, and to assess the response to exercise training on exercise capacity and muscular structure and function in these groups.

METHODS

Quadriceps function (isokinetic dynamometry), body composition (dual-energy x-ray absorptiometry), and vastus lateralis muscle biopsies were analyzed before and after a 12-week lasting training-program in 35 RTx patients, 16 HD patients, and 21 healthy controls.

RESULTS

At baseline, myosin heavy chain (MyHC) isoform composition and enzyme activities were not different between the groups. VO2peak and muscle strength improved significantly and comparably over the training-period in RTx, HD patients and controls (p(time)<0.05). The proportion of MyHC type I isoforms decreased (p(time)<0.001) and type IIa MyHC isoforms increased (p(time)<0.05). The 3-hydroxyacyl-CoA-dehydrogenase activity increased (p(time)=0.052). Intrinsic muscular changes were not significantly different between groups. In the HD group, changes in lean body mass were significantly related to changes in muscle insulin-like growth factor (IGF)-II and IGF binding protein-3.

CONCLUSIONS

Abnormalities in metabolic enzyme activities or muscle fiber redistribution do not appear to be involved in muscle dysfunction in RTx and HD patients. Exercise training has comparable beneficial effects on functional and intrinsic muscular parameters in RTx patients, HD patients, and controls. In HD patients, the anabolic response to exercise training is related to changes in the muscle IGF system.

Nandrolone Decanoate as Anabolic Therapy in Chronic Kidney Disease: A Randomized Phase II Dose-Finding Study

BACKGROUND/AIMS

In patients with chronic kidney disease (CKD) receiving adequate erythropoietin therapy, the ideal dose of nandrolone decanoate (ND) to enhance muscle mass is not known.

METHODS

In this phase II dose-finding study, 54 patients with CKD stage 5 were randomized to either low, medium or high doses of ND (50, 100 or 200 mg/week for 24 weeks, respectively, in males; doses halved in females), while 7 patients acted as non-randomized controls. The primary outcome measure was appendicular lean mass (ALM) by dual-energy X-ray absorptiometry. Fluid overload (hydration of the fat-free mass) and indicators of physical functioning were secondary measures. Harms were also recorded. Data were analysed using Quade's (1967) non-parametric analysis of covariance.

RESULTS

ND increased ALM in a dose-responsive manner (change scores = 0.3 +/- 0.3 vs. 0.8 +/- 0.3 vs. 1.5 +/- 0.5 vs. 2.1 +/- 0.4 kg, control vs. low vs. medium vs. high dose groups, respectively, p < 0.001) with no increases in fluid overload but no consistent effect on physical functioning. The highest dose of ND (100 mg/week) was intolerable in females because of virilizing effects.

CONCLUSION

If goals of future studies are to improve body composition, dosing of ND up to 200 mg/week in males and 50 mg/week in females should be investigated. However, to realize improvements in physical functioning, future phase III trials of ND may require additional interventions such as exercise training.

GFR Estimation Using Cystatin C Is Not Independent of Body Composition

BACKGROUND

Cystatin C (CysC) is an endogenous marker of glomerular filtration rate (GFR) that is claimed to be unaffected by body composition. In this study, we tested this speculation.

METHODS

In 77 patients with chronic kidney disease (mean age, 65.1 +/- 11.9 [SD] years; mean indexed GFR, 45.7 +/- 28.6 mL/min/1.73 m(2) [0.76 +/- 0.48 mL/s]), we evaluated kidney function (GFR) by means of inulin clearance. CysC level was determined by using a particle-enhanced turbidimetric immunoassay. Total lean (LM) and fat masses were measured by means of dual-energy x-ray absorptiometry. Multiple regression was used to analyze relationships between absolute GFR, LM, fat mass, demographic and anthropometric variables (age, sex, height, and weight), and CysC levels. Then prediction equations were built that included only CysC level or CysC level and LM. Their performance to predict absolute GFR was evaluated in a subset of patients with extreme body composition (LM or fat mass > +/-1 SD of the entire sample).

RESULTS

Only absolute GFR and LM significantly explained variance in CysC levels, and an equation including LM explained more variance in absolute GFR than an equation including CysC level alone. Consequently, the equation including LM performed better than the equation with only CysC level, especially in patients with extreme body composition, showing reduced bias and improved limits of agreement and accuracy (71.4% versus 51.4% of patients' predicted GFR did not deviate by >30% of GFR).

CONCLUSION

LM is a previously unrecognized, but important, factor affecting CysC level, and GFR estimation improves when including LM. CysC level is not independent of body composition, as previously assumed, and hence accounting for body composition improves CysC-based GFR estimation.

Progressive resistance training during hemodialysis: Rationale and method of a randomized-controlled trial

Skeletal muscle wasting in patients receiving maintenance hemodialysis (HD) has been well documented. The rationale for prescribing progressive resistance training (PRT) in this cohort in an attempt to reverse this catabolism and induce a wide spectrum of physiological, functional, and psychological health-related adaptations is extremely strong. Unfortunately, the barriers to exercise adoption in this cohort are many, which may explain the persisting sedentariness of this population and the lack of widespread clinical programs such as are now commonplace in cardiac rehabilitation and pulmonary rehabilitation units. Current health care practices for HD patients do not address the negative health issues of inactivity and muscle wasting. Therefore, we conducted the first randomized-controlled trial to prescribe PRT during maintenance HD treatment. The purpose of this paper is to present the rationale and methodology that we utilized for implementing intradialytic PRT in a conventional outpatient HD clinic. Potential areas for modification of PRT regimens in this setting are also presented.

Skeletal muscle dysfunction in chronic renal failure: effects of exercise

A number of chronic illnesses such as renal failure (CRF), obstructive pulmonary disease, and congestive heart failure result in a significant decrease in exercise tolerance. There is an increasing awareness that prescribed exercise, designed to restore some level of physical performance and quality of life, can be beneficial in these conditions. In CRF patients, muscle function can be affected by a number of direct and indirect mechanisms caused by renal disease as well as various treatment modalities. The aims of this review are twofold: first, to briefly discuss the mechanisms by which CRF negatively impacts skeletal muscle and, therefore, exercise capacity, and, second, to discuss the available data on the effects of programmed exercise on muscle function, exercise capacity, and various other parameters in CRF.

Cardiac rehabilitation and survival of dialysis patients after coronary bypass

Patients who are on renal dialysis are at high risk for cardiac death and have a large burden of cardiovascular disease and cardiovascular disease risk factors. Cardiac rehabilitation can promote improved survival of nondialysis patients after coronary artery bypass grafting (CABG) surgery and is covered by Medicare, but no previous studies have investigated whether dialysis patients' survival after CABG may be improved as a function of cardiac rehabilitation. A prospective cohort study was conducted using Medicare claims (1998 to 2002) for CABG and cardiac rehabilitation and patient information from the United States Renal Data System database for 6215 renal patients who initiated hemodialysis and underwent CABG between January 1, 1998, and December 31, 2002, with mortality follow-up to December 31, 2003. Cardiac rehabilitation was defined by Current Procedural Terminology codes for monitored and nonmonitored exercise in Medicare claims data. Dialysis patients who received cardiac rehabilitation after CABG had a 35% reduced risk for all-cause mortality and a 36% reduced risk for cardiac death compared with dialysis patients who did not receive cardiac rehabilitation, independent of sociodemographic and clinical risk factors, including recent hospitalization. Only 10% of patients received cardiac rehabilitation after CABG, compared with an estimated 23.4% of patients in the general population, and lower income patients of all ages as well as women and black patients who were aged 65+ were significantly less likely to receive cardiac rehabilitation services. This observational study suggests a survival benefit of cardiac rehabilitation for dialysis patients after CABG.