Pelagia Koufaki

Effects of exercise training on aerobic and functional capacity of end-stage renal disease patients

The aim was to assess the effects of exercise training on aerobic and functional capacity of patients with end‐stage renal disease (ESRD). Patients completed an incremental exercise test on a cycle ergometer to determine VO2 peak and VO2 at ventilatory threshold (VT; V‐slope). On a separate day they performed two constant load exercise tests on a cycle ergometer at 90% of VT and at a workload of 33 W, to determine VO2 kinetics. Functional capacity was assessed using measurements of sit‐to‐stands (STS‐5, STS‐60) and a walk test. Dialysis patients were randomly allocated to an exercise (ET: n=18, age=57·3 years) or control (C: n=15, age=50·5 years) group. The ET group participated in an exercise training programme involving cycling for 3 months. Repeated measures ANOVA revealed significant time by group interactions (P < 0·05) following training for VO2 peak (ET: 17 ± 6·1 versus 19·9 ± 6·3, C: 19·5 ± 4·7 versus 18·8 ± 4·9 ml kg min–1) and VO2–VT (ET: 10·7 ± 3·5 versus 11·8 ± 3·3, C:12·9 ± 3·2 versus 11·9 ± 3·5 ml kg min–1). VO2 kinetics remained unchanged in both groups at 90% ‐VT, but a trend (P=0·059) towards faster kinetics at the 33 W was observed (ET: 49·6 ± 19·5 versus 37·8 ± 12·7, C: 42·8 ± 13 versus 49·4 ± 20·2 s). Significant time by group interactions (P < 0·05) were also observed for STS‐5 (ET: 14·7 ± 6·2 versus 11·0 ± 3·3, C: 12·8 ± 4·4 versus 12·7 ± 4·8 s) and STS‐60 measurements (ET: 21·2 ± 7·2 versus 26·9 ± 6·2, C: 23·7 ± 6·8 versus 24·1 ± 7·2). Three months of exercise rehabilitation significantly improves peak exercise capacity of patients with ESRD. Measurements of VO2 kinetics and functional capacity suggest that longer time might be needed to induce peripheral adaptations.

Assessing the efficacy of exercise training in patients with chronic disease

PURPOSE The purpose of this study was to evaluate the meaningfulness of exercise training responses in patients with end stage renal disease (ESRD). METHODS Eighteen ESRD patients [(mean +/- SD); 54.3 +/- 17.1 yr] completed a training regime progressing to accumulate 40 min of stationary cycling, three times per week for 6 months. .VO(2peak) determined via incremental cycle ergometer protocol, and .VO(2) kinetics determined from a transition from unloaded pedalling to an exercise intensity corresponding to 90% of VT, were assessed at baseline and at 3 and 6 months of training. RESULTS Repeated measures analysis of variance revealed significant changes (P < 0.05) on the time factor for .VO(2peak), VO(2)-V(T), and .VO(2) kinetics. Post hoc analysis revealed that .VO(2peak) and .VO(2) kinetics significantly (P < 0.05) improved at 3 months of training with no further improvements thereafter. Analysis of individual subject response data revealed that after 3 months of training, 61% of the patients improved .VO(2peak) by greater than the standard error of measurement (SEM = 0.07 L.min(-1)). At 6 months of training, approximately 89% of the patients improved by more than the SEM .VO(2) kinetics improved by more than the SEM (12.3 s) at 3 months of training in approximately 55% of the patients, with no increase in the number of patients exhibiting faster time constants after 6 months of training. CONCLUSION Although conventional statistical analyses indicate that exercise training favorably alters .VO(2peak) and oxygen uptake kinetics of patients with ESRD, it is apparent that considerable interindividual variability exists in the response to training. Consideration of the SEM data underscores the heterogeneity of adaptive response in this patient group and may be valuable in assessing the efficacy of therapeutic exercise rehabilitation.

Low-volume high-intensity interval training vs continuous aerobic cycling in patients with chronic heart failure: A pragmatic randomised clinical trial of feasibility and effectiveness

OBJECTIVES The health benefits of high-intensity interval training in cardiac rehabilitation warrant further research. We compared the effectiveness of low-volume high-intensity interval training vs continuous aerobic exercise training in chronic heart failure. DESIGN/SETTINGS Unblinded, two arm parallel design with random assignment to exercise interventions in out-patient hospital rehabilitation gym. METHODS Patients with signs of chronic heart failure and ejection fraction < 45%, (mean age: 59.1 years (standard deviation (SD) 8.6); 3 women) completed 6 months of exercise using continuous aerobic exercise training (n = 9) or high-intensity interval training (n = 8). Cardiorespiratory fitness was determined during cycle ergometry using respiratory gas exchange analysis. Functional capacity was assessed via sit-to-stand and gait speed. Quality of life was assessed using the MOS Short-Form 36 and Minnesota living with heart failure questionnaires. Cardiac autonomic regulation was assessed using Heart Rate Variability. RESULTS Analysis of Covariance revealed significant time effects but no group × time interactions for exercise and functional capacity outcomes. Peak oxygen uptake (VO2peak) improved by a mean of 14.9% (SD 16.3%) from baseline and by 22% (SD 28.3) at ventilatory threshold in both groups. Sit-to-stand (11.9 (SD 11%)) and gait speed (16.0 (SD 19%)) improved similarly in both groups. No changes in quality of life or heart rate variability were noted. Training adaptations in high-intensity interval training were achieved despite a significantly reduced time commitment and total work volume compared to continuous aerobic exercise training. CONCLUSION Low-volume high-intensity interval training is a feasible and well tolerated training modality in cardiac rehabilitation settings, but is not more effective than continuous aerobic exercise training.

Exercise Therapy in Individuals With Chronic Kidney Disease: A Systematic Review and Synthesis of the Research Evidence

Chronic kidney disease (CKD) is becoming a serious health problem throughout the world and is one of the most potent known risk factors for cardiovascular disease (CVD) which is considered the leading cause of morbidity and mortality in this cohort of patients. Additional independent risk factors for poor health outcomes among many include diabetes, physical inactivity and physical dysfunction. Physical inactivity partly contributes to the accelerated deterioration of physical function in people in all stages of CKD, to levels that significantly impact on clinically and patient important outcomes such as morbidity, employment, quality of life (QoL) and ultimately survival. Ongoing research aims to determine the effectiveness and impact of exercise rehabilitation on reducing/managing the risk of CVD, alleviating physical function limitations, preventing disability and enhancing QoL. Current research also aims to elucidate the mechanisms via which exercise therapy may contribute to clinically relevant benefits.

Skeletal muscle morphology and capillarization of renal failure patients receiving different dialysis therapies

The morphology of gastrocnemius muscles was examined in RFPs (renal failure patients) being treated using HD (haemodialysis) and CAPD (continuous ambulatory peritoneal dialysis). RFPs (n=24) volunteered to participate in the present study. Twelve RFPs (five women and seven men; mean age, 55 years) were undergoing CAPD treatment and 12 RFPs (two women and ten men; mean age, 62 years) were undergoing HD treatment. Muscle biopsies from gastrocnemius muscles were found not to differ (P>0.05) in fibre type distribution, MyHC (myosin heavy chain) expression or fibre CSA (cross-sectional area) between the two groups. There were, however, significant differences (P<0.05) in CC/F (capillary contact/fibre), C/F (capillary to fibre ratio) and cytochrome c oxidase activity. The HD group had 33% more CC/F, with a 19% higher C/F and 33% greater cytochrome c activity in glycolytic fibres (II) than the CAPD group. There were no apparent differences in age, gender, co-morbidity, self-reported physical activity or physical functioning between the two groups, which could account for the difference in muscle capillarity between the groups. The HD patients were, however, administered heparin as a routine part of the dialysis therapy. The possibility is discussed that heparin in combination with mild anaemia and acidosis may have augmented angiogenesis in the HD patients.

Exercise Counselling Practices for Patients with Chronic Kidney Disease in the UK: A Renal Multidisciplinary Team Perspective

Background: Patients with chronic kidney disease (CKD) have elevated cardiovascular disease (CVD) risk. Physical activity (PA) is a strong and independent CVD risk factor, and despite the fact that current clinical practice guidelines recommend simultaneous treatment of multiple risk factors for optimum management of CKD, PA is rarely addressed by renal care teams. The aim of this observational cross-sectional survey was to document current exercise/PA practices across renal units in the UK, and capture views and experiences regarding the provision of PA/exercise options for patients with CKD. Methods: An 18-item online survey questionnaire regarding exercise counselling practice patterns was administered to 565 multidisciplinary renal care professionals. Results: 142 individuals (25% response rate) completed the questionnaire. Overall, 42% of respondents discussed and encouraged PA, but only 18 and 11% facilitated implementation of PA for their patients. Nephrologists (p < 0.003) were more likely to prescribe or recommend PA compared to professionals with a nursing background and believed that specific renal rehabilitation services, including an active PA/exercise component, should be available to all patients (p < 0.01). The most commonly reported barriers for the development and implementation of PA/exercise options included lack of funding, time, and knowledgeable personnel, such as physiotherapists or other exercise professionals. Conclusion: Beliefs and attitudes towards PA amongst members of the renal multidisciplinary team are encouraging. However there is a big gap between believing in the benefits of PA and promoting/implementing PA for patient benefit. This gap needs to be minimised by at least trying to address some of the reported barriers.

Long-term pulse wave velocity outcomes with aerobic and resistance training in kidney transplant recipients - A pilot randomised controlled trial

Background This pilot study examined long-term pulse wave velocity (PWV) and peak oxygen uptake (VO2peak) outcomes following a 12-week moderate-intensity aerobic or resistance training programme in kidney transplant recipients. Method Single-blind, bi-centre randomised controlled parallel trial. 42 out of 60 participants completed a 9-month follow-up assessment (Aerobic training = 12, Resistance training = 10 and usual care = 20). Participants completed 12 weeks of twice-weekly supervised aerobic or resistance training. Following the 12-week exercise intervention, participants were transitioned to self-managed community exercise activity using motivational interviewing techniques. Usual care participants received usual encouragement for physical activity during routine clinical appointments in the transplant clinic. PWV, VO2peak, blood pressure and body weight were assessed at 12 weeks and 12 months, and compared to baseline. Results ANCOVA analysis, covarying for baseline values, age, and length of time on dialysis pre-transplantation, revealed a significant mean between-group difference in PWV of -1.30 m/sec (95%CI -2.44 to -0.17, p = 0.03) between resistance training and usual care groups. When comparing the aerobic training and usual care groups at 9-month follow-up, there was a mean difference of -1.05 m/sec (95%CI -2.11 to 0.017, p = 0.05). A significant mean between-group difference in relative VO2peak values of 2.2 ml/kg/min (95% CI 0.37 to 4.03, p = 0.02) when comparing aerobic training with usual care was revealed. There was no significant between group differences in body weight or blood pressure. There were no significant adverse effects associated with the interventions. Conclusions Significant between-group differences in 9-month follow-up PWV existed when comparing resistance exercise intervention with usual care. A long-term between-group difference in VO2peak was only evident when comparing aerobic intervention with usual care. This pilot study, with a small sample size, did not aim to elucidate mechanistic mediators related to the exercise interventions. It is however suggested that a motivational interviewing approach, combined with appropriate transition to community training programmes, could maintain the improvements gained from the 12-week exercise interventions and further research in this area is therefore warranted. Trial registration study number: ISRCTN43892586.