Anabolic interventions in ESRD

A randomized controlled trial of exercise to prevent muscle mass and functional loss in elderly hemodialysis patients: Rationale, study design, and baseline sample

Background

Elderly maintenance hemodialysis (MHD) patients exhibit muscle wasting and impaired physical function. This trial determines whether MHD patients benefit from a 12-week home-based exercise program, protein supplementation, or both.

Design

and Methods: This is a randomized, blinded controlled trial involving 60 elderly MHD patients with impaired exercise capacity and function. Patients are randomized into either a homebased exercise program or normal care over a 12-week period. Measures at baseline include peak VO₂, strength and body composition as well as cognitive and disease-specific questionnaires. Muscle biopsies are obtained and analyzed for protein signaling, expression of IGF-1, androgen receptors, and myostatin.

Results

At baseline, patient characteristics in the exercise and normal care groups were similar by age, gender and anthropomorphic measures. Peak VO₂ was impaired (14.7 ± 3.3 ml/kg/min), representing 55 ± 14% of the age-predicted value. Six-minute walk distance was 322 ± 71 m, and the mean 1-min sit to stand test was 18 ± 8 repetitions, representing 69 ± 16% and 55 ± 22% of the age-predicted values, respectively. Indices of muscle function, including upper and lower body and hand grip strength all indicate marked impairment. Quality of life (QoL) using the SF36, the Beeson cognitive test, and KDQOL all suggest marked impairments compared to age-expected reference values for non-MHD patients.

Conclusions

Patients undergoing MHD exhibit markedly reduced physical function and QoL. Thus, there are potentially significant gains to be made through a program of aerobic and resistance exercise. We anticipate this trial will demonstrate that home-based exercise improves cardiopulmonary function, protein signaling and QoL, and increases muscle mass, strength, and body composition.

Effects of Aerobic Exercise During Hemodialysis on Physical Functional Performance and Depression

Previous studies have concluded that exercise training is beneficial to patients on hemodialysis (HD). Results, however, have shown that differences in the type, intensity, and frequency of physical exercise lead to variability in its effects on physical functional performance and depression. Further research is thus warranted. Our aim was to evaluate the effects of aerobic exercise on physical functional performance and depression during HD. Using a pretest–posttest control group design, we recruited HD patients and nonrandomly assigned them to an exercise group ( n = 13) that completed a 12-week aerobic exercise program during HD or a control group ( n = 11) that did no exercise during HD. The primary outcome measures were physical functional performance, as evaluated by the 6-min walk test and the sit-to-stand test, and depression, as evaluated by the Beck Depression Inventory II. The secondary outcome measures were albumin and triglyceride levels and hematocrit. Results revealed significant between-group differences in physical functional performance and depression but not in albumin level, hematocrit, or triglyceride level. Findings suggest that exercise may play a critical role in physical functional performance and may decrease depression. Exercise should be encouraged and performed during HD in HD centers.

Anabolic Effect of Exercise Training in People with End-Stage Renal Disease on Hemodialysis: A Systematic Review with Meta-analysis

PURPOSE

The primary purpose of this systematic review was to evaluate the anabolic effect of exercise intervention in adults with end-stage renal disease on hemodialysis (HD). The secondary objectives were to evaluate the influences of participant characteristics and exercise parameters on changes in muscle size.

METHODS

Electronic databases (Cochrane, CINAHL, EMBASE, PEDro, PubMed and SCOPUS) were searched from inception to November 2012. Randomized clinical trials published in English that included adults on HD undergoing an exercise intervention where muscle mass was measured as an outcome were included in this review. Two reviewers independently selected the studies, extracted data, and assessed risk of bias within the included studies. RESULTS were then combined by meta-analysis. The effect of exercises was determined using a standardized mean difference (SMD), expressed as Hedges' g, computed using a random effects model.

RESULTS

Seven SMDs extracted from five studies were included for final analysis. Strength training was used in all studies; one study used aerobic and mixed strength and aerobic training with two subgroups of participants. The overall effect of exercise on muscle mass was statistically significant (SMD: 0.272; 95% CI, 0.020-0.525).

CONCLUSIONS

Our results confirm a small but significant effect of strengthening exercise as an anabolic intervention to increase muscle mass. Exercise training should be included in routine management of people on maintenance HD. Although current results indicate that one in nine people on HD is likely to benefit from exercise intervention, parameters influencing these results require further research.

Effects of modality change and transplant on peak oxygen uptake in patients with kidney failure

BACKGROUND

Exercise capacity as measured by peak oxygen uptake (Vo₂(peak)) is low in hemodialysis patients. The present study assesses determinants of VO₂(peak) in patients with chronic kidney failure who either changed kidney replacement modality to frequent hemodialysis therapy or received a kidney transplant.

STUDY DESIGN

Cohort study with assessment at baseline and 6 months after modality change.

SETTING & PARTICIPANTS

Participants included nondiabetic individuals receiving conventional hemodialysis who: (1) remained on conventional hemodialysis therapy (n = 13), (2) changed to short daily hemodialysis therapy (n = 10), or (3) received a transplant (n = 5) and (4) individuals who underwent a pre-emptive transplant (n = 15). Additionally, 34 healthy controls were assessed at baseline only.

PREDICTOR

Modality change.

MEASUREMENT & OUTCOMES

Exercise capacity, assessed using the physiologic components of the Fick equation (Vo₂ = cardiac output × a-vo₂(dif), where a-vo₂(dif) is arterial to venous oxygen difference) was determined using measurement of Vo₂(peak) and cardiac output during symptom-limited exercise testing. Analysis of covariance was used to compare differences in changes in Vo₂(peak), cardiac output, heart rate, stroke volume, and a-vo₂(dif) at peak exercise between participants who remained on hemodialysis therapy and those who underwent transplant.

RESULTS

Transplant was the only modality change associated with a significant change in Vo₂(peak), occurring as a result of increased peak cardiac output and reflecting increased heart rate without a change in peak a-vo₂(dif) despite increased hemoglobin levels. There were no differences in participants who changed to daily hemodialysis therapy compared with those who remained on conventional hemodialysis therapy.

LIMITATIONS

Small nonrandomized study.

CONCLUSIONS

Vo₂(peak) increases significantly after kidney transplant, but not with daily hemodialysis; this improvement reflects increased peak cardiac output through increased peak heart rate. Despite statistical significance, the increase in Vo₂(peak) was not clinically significant, suggesting the need for interventions such as exercise training to increase Vo₂(peak) in all patients regardless of treatment modality.