Effect of exercise training on estimated GFR, vascular health, and cardiorespiratory fitness in patients with CKD: a pilot randomized controlled trial

BACKGROUND

Exercise capacity, which is predictive of all-cause mortality and cardiovascular disease risk, is reduced significantly in patients with non-dialysis-dependent chronic kidney disease. This pilot study examined the effect of moderate-intensity exercise training on kidney function and indexes of cardiovascular risk in patients with progressive chronic kidney disease stages 3 to 4.

STUDY DESIGN

Single-blind, randomized, controlled, parallel trial.

SETTING & PARTICIPANTS

20 patients (aged 18-80 years; 17 men) randomly assigned to rehabilitation (n=10) or usual care (n=10). Participants were included if they were 18 years or older and had evidence of rate of decline in creatinine-based estimated glomerular filtration rate (eGFRcr)≥2.9mL/min/1.73m(2) per year for 12 months preintervention. Patients were excluded if they had unstable medical conditions or had recently started regular exercise.

INTERVENTION

The rehabilitation group received resistance and aerobic training (3 days per week) for a 12-month period. The usual care group received standard care.

OUTCOMES

Kidney function assessed by comparing mean rate of change in eGFRcr (mL/min/1.73m(2) per year) from a 12-month preintervention period against the 12-month intervention period. Pulse wave velocity (PWV), peak oxygen uptake (Vo2peak), and waist circumference assessed at 0, 6, and 12 months.

MEASUREMENTS

eGFR assessed using creatinine, cystatin C (eGFRcys), and a combination of both values (eGFRcr-cys).

RESULTS

18 participants (rehabilitation, 8; usual care, 10) completed the study. A significant mean difference in rate of change in eGFRcr (+7.8±3.0 [95% CI, 1.1-13.5] mL/min/1.73m(2) per year; P=0.02) was observed between the rehabilitation and usual care groups, with the rehabilitation group demonstrating a slower decline. No significant between-group mean differences existed in absolute eGFRcr, eGFRcr-cys, or eGFRcys at 12 months of study intervention. Significant between-group mean differences existed in PWV (-2.30 [95% CI, -3.02 to -1.59] m/s), waist circumference (-7.1±12.8 [95% CI, -12.4 to -3.2] cm), and Vo2peak (5.7 [95% CI, 1.34-10.10] mL/kg/min). Change in eGFRcr was correlated inversely with PWV (r=-0.5; P=0.04) at 12 months.

LIMITATIONS

Small sample size, inconsistency between primary and secondary measures of kidney function.

CONCLUSIONS

The effect of a 1-year exercise intervention on progression of kidney disease is inconclusive. A larger study with longer follow-up may be necessary.

Habitual functional electrical stimulation therapy improves gait kinematics and walking performance, but not patient-reported functional outcomes, of people with multiple sclerosis who present with foot-drop

BACKGROUND

People with Multiple Sclerosis (pwMS) often experience a disturbed gait function such as foot-drop. The objective of this pilot study was to investigate the medium term effects of using Functional Electrical Stimulation (FES) to treat foot-drop over a period 12 weeks on gait and patient reported outcomes of pwMS.

METHODS AND FINDINGS

Nine pwMS aged 35 to 64 (2 males, 7 females) were assessed on four occasions; four weeks before baseline, at baseline and after six weeks and twelve weeks of FES use. Joint kinematics and performance on the 10 meter and 2 minute walk tests (10WT, 2 minWT) were assessed with and without FES. Participants also completed the MS walking Scale (MSWS), MS impact scale (MSIS29), Fatigue Severity Score (FSS) and wore an activity monitor for seven days after each assessment. Compared to unassisted walking, FES resulted in statistically significant improvements in peak dorsiflexion in swing (p = 0.006), 10MWT (p = 0.006) and 2 minWT (p = 0.002). Effect sizes for the training effect, defined as the change from unassisted walking at baseline to that at 12 weeks, indicated improved ankle angle at initial contact (2.6°, 95% CI -1° to 4°, d = 0.78), and a decrease in perceived exertion over the 2 min walking tests (-1.2 points, 95% CI -5.7 to 3.4, d = -0.86). Five participants exceeded the Minimally Detectable Change (MDC) for a training effect on the 10mWT, but only two did so for the 2 minWT. No effects of the use of FES for 12 weeks were found for MSWS, MSIS29, FSS or step count.

CONCLUSION

Although FES to treat foot-drop appears to offer the potential for a medium term training effect on ankle kinematics and walking speed, this was not reflected in the patient reported outcomes. This observed lack of relationship between objective walking performance and patient reported outcomes warrants further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01977287.

Intra-dialytic exercise training: a pragmatic approach

This continuing education paper outlines the skills and knowledge required to plan, implement and evaluate a pragmatic approach to intra-dialytic exercise training.

AIM

The aim of this continuing education article is to enable the nephrology multi-disciplinary team (MDT) to plan, implement and evaluate the provision of intra-dialytic exercise training for patients receiving haemodialysis therapy.

LEARNING OUTCOMES

After reading this article the reader should be able to: Appreciate the level of evidence base for the clinical effectiveness of renal exercise rehabilitation and locate credible sources of research and educational information Understand and consider the need for appropriate evaluation and assessment outcomes as part of a renal rehabilitation plan Understand the components of exercise programming and prescription as part of an integrated renal rehabilitation plan Develop a sustainable longer term exercise and physical activity plan.

Experiences of functional electrical stimulation (FES) and ankle foot orthoses (AFOs) for foot-drop in people with multiple sclerosis

PURPOSE

A constructivist phenomenological study explored impacts of ankle foot orthoses (AFOs) or functional electrical stimulation (FES) on people with foot-drop from multiple sclerosis (MS).

METHOD

Focus groups following topic guides were analysed using interpretative phenomenological analysis, with researcher reflexivity, participant verification and peer checking of analysis. Participants with sustained use of the devices (under 2 y) were invited from two quantitative studies that (a) investigated immediate FES effects (n = 12) and (b) compared habitual use of AFO (n = 7) or FES (n = 6). Two focus groups addressed AFO (n = 4) and FES (n = 6) experiences.

RESULTS

Similar numbers of positive and negative aspects were described for AFO and FES. Both reduced fatigue, improved gait, reduced trips and falls, increased participation, and increased confidence; greater balance/stability was reported for AFOs, and increased walking distance, fitness and physical activity for FES. Barriers to both included avoiding reliance on devices and implications for shoes and clothing; a non-normal gait pattern was reported for AFO, and difficulties of application and limitations in the design of FES. However, participants felt the positives outweighed the negatives.

CONCLUSIONS

Participants felt benefits outweighed the drawbacks for AFO and FES; greater understanding of user preferences and satisfaction may increase likelihood of usage and efficacy. Implications for Rehabilitation Interventions to reduce the impacts of foot-drop in people with multiple sclerosis (MS) are important to optimise physical activity participation and participation in life; they include ankle foot orthoses (AFOs) and functional electrical stimulation (FES). Research is lacking regarding user satisfaction and perceived outcomes, therefore, two separate focus groups were conducted from a constructivist phenomenological perspective to explore the impacts of AFOs (n = 4) and FES (n = 6) on people with foot-drop from MS. Some similar positive aspects of AFO and FES use were described, including reduced fatigue, improved gait and fewer trips and falls, while common barriers included finding the device cumbersome, uncomfortable, and inconvenient, with some psychological barriers to their use. On balance, the impacts of the devices on improving activities and participation were more important for participants than practical barriers, highlighting the importance of combining understanding of individual experiences and preferences with clinical decision-making when prescribing a device to manage foot-drop.

Quantification of gait kinematics and walking ability of people with multiple sclerosis who are new users of functional electrical stimulation

OBJECTIVE

To assess whether the application of Functional Electrical Stimulation improves gait kinematics and walking ability in people with multiple sclerosis who experience foot drop.

DESIGN

Acute open labelled comparative observation trial.

PARTICIPANTS

Twelve people (3 females, 9 males, EDSS 2-4) with relapsing remitting multiple sclerosis (47.8 years (standard deviation 6.6)) who were new users of functional electrical stimulation.

METHODS

Gait kinematics were recorded using 3D gait analysis. Walking ability was assessed through the 10-m walk test and the 6-min walk test. All assessments were performed with and without the assistance of functional electrical stimulation. The effect of functional electrical stimulation was analysed using paired t-tests.

RESULTS

Ankle dorsiflexion at initial contact (p = 0.026), knee flexion at initial contact (p = 0.044) and peak knee flexion during swing (p = 0.011) were significantly greater whilst walking with Functional Electrical Stimulation. The increased peak dorsiflexion in swing of nearly 4 degrees during functional electrical stimulation assisted walking approached significance (p = 0.069). The 10-m walk time was significantly improved by functional electrical stimulation (p = 0.004) but the 6 min walk test was not.

CONCLUSION

The acute application of functional electrical stimulation resulted in an orthotic effect through a change in ankle and knee kinematics and increased walking speed over a short distance in people with multiple sclerosis who experience foot drop.

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.

The Influence of Obesity on Patient Reported Outcomes following Total Knee Replacement

This study retrospectively analysed the effects of obesity as described by Body Mass Index (BMI) on patient reported outcomes following total knee replacement. Participants (105 females and 66 males) who had undergone surgery under the care of a single surgeon were included in the review and were grouped according to their preoperative BMI into nonobese (BMI < 30 kg/m(2)), (n = 73) obese (BMI ≥ 30 kg/m(2)) (n = 98). Oxford Knee Score (OKS) and Short Form 12 scores (SF12) were taken preoperatively and 6 and 12 months after surgery to analyse differences between groups in the absolute scores as well as changes from before to after surgery. Preoperatively, the obese group had a significantly poorer OKS compared to non obese (44.7 versus 41.2, P = 0.003). There were no statistically significant group effects on follow-up or change scores of the OKS and SF12. Correlations coefficients between BMI and follow-up and change scores were low (r < 0.201). There were no significant differences in the number of complications and revisions (local wound infection, 6.7% non obese, 11% obese, postoperative systemic complication, 8% non obese, 12% obese, revision, 4% nonobese, 3% obese). In conclusion, our findings indicate similar degrees of benefits from the surgery irrespective of patient BMI.

The effects of tuning an ankle-foot orthosis footwear combination on kinematics and kinetics of the knee joint of an adult with hemiplegia

The effects of tuning the AFO footwear combination (AFOFC) for an adult with post-stroke hemiplegia were investigated. Gait analysis and tuning were carried out using a Vicon 3D motion analysis system and two force plates. Tuning of the AFOFC was accomplished by gradually modifying its design over a number of gait trials, to achieve optimal (i.e., as close as possible to normal, within the capability of the patient) knee kinematics and alignment of the Ground Reaction Force vector (GRF) relative to the knee joint. Heel wedges and a stiff rocker were used to tune mid-stance and terminal stance, respectively. Temporal-spatial parameters and selected kinetic and kinematic variables were compared between the non-tuned AFOFC, the tuned AFOFC immediately after tuning, and the tuned AFOFC after three months. There were several changes after three months compared to the non-tuned AFOFC, including improvement in stride length and a reduction in knee hyperextension. A subjective reduction in knee pain and improvement in function were also reported. The feasibility and the lack of objective evidence of tuning AFOFCs as a part of a clinical service need to be addressed in future research.

Patients receiving maintenance dialysis have more severe functionally significant skeletal muscle wasting than patients with dialysis-independent chronic kidney disease

BACKGROUND

Chronic renal replacement therapy patients exhibit reduction in skeletal muscle function as a result of a combination of metabolic effects and muscle fibre size reduction. The aim of this study was to compare muscle mass with function in patients with chronic kidney disease (CKD) at stages 4 and 5 on haemodialysis (HD) and peritoneal dialysis (PD), and investigate the associations of muscle wasting in a cross-sectional cohort.

METHODS

We studied 134 patients (60 HD, 28 PD and 46 CKD 4). The three groups were well matched for age, sex, diabetes and dialysis vintage. Cross-sectional area (CSA) of muscle and fat was measured from a standardized multi-slice CT scan of a 6 cm long section of thigh. CSA of soft tissue was taken from appropriate fat and muscle densities. Functional assessment was by the sit-to-stand 60 test, assessing both the number of sit-to-stands possible under controlled conditions in 60 s (STS 60), and the time taken to perform five sit-to-stand movements (STS 5). Data were collected on a wide range of potential determinants of muscle CSA.

RESULTS

There were no significant differences in haemoglobin between males or females or between any of the groups studied. Serum phosphate and calcium-phosphate product were higher in HD patients as compared to CKD4 patients, but there were no differences in these variables when comparing PD patients with either CKD4 or HD patients. Muscle CSA correlated well with objective functional assessments in males (STS 60 R = 0.52, P<0.0001) and females (R = 0.41, P = 0.004), and STS performance was reduced in dialysed patients as compared with CKD 4. Univariate analysis demonstrated that muscle CSA was associated with serum albumin concentration (R = 0.49, P<0.0001), age (R = -0.35, P = 0.005) and C-reactive protein (R = -0.34, P = 0.004). Creatinine clearance, dialysis adequacy, dialysis vintage and time-averaged serum bicarbonate, calcium and phosphate concentrations were not correlated with muscle CSA.

CONCLUSION

In conclusion, patients with dialysis-treated CKD 5 exhibited more functionally significant muscle wasting than patients with CKD 4. This may be amenable to modification with targeted exercise or amelioration of factors associated with observed differences in muscle mass.

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.

Nutritional status, functional capacity and exercise rehabilitation in end-stage renal disease

A significant percentage of patients with end-stage renal disease are malnourished and/or muscle wasted. Uremia is associated with decreased protein synthesis and increased protein degradation. Fortunately, nutritional status has been shown to be a modifiable risk factor in the dialysis population. It has long been proposed that exercise could positively alter the protein synthesis-degradation balance. Resistance training had been considered as the only form of exercise likely to induce anabolism in renal failure patients. However, a small, but growing, body of evidence indicates that for some dialysis patients, favourable improvements in muscle atrophy and fibre hypertrophy can be achieved via predominantly aerobic exercise training. Moreover, some studies tentatively suggest that nutritional status, as measured by SGA, can also be modestly improved by modes and patterns of exercise training that have been shown to also increase muscle fibre cross-sectional area and improve functional capacity. Functional capacity tests can augment the information content of basic nutritional status assessments of dialysis patients and as such are recommended for routine inclusion as a feature of all nutritional status assessments.

Atrophy of non-locomotor muscle in patients with end-stage renal failure

BACKGROUND

All previous histological studies of skeletal muscles of patients with renal failure have used locomotor muscle biopsies. It is thus unclear to what degree the observed abnormalities are due to the uraemic state and how much is due to disuse. The present study was undertaken to attempt to investigate this question by examining a non-locomotor muscle (rectus abdominis) in patients with end-stage renal failure.

METHODS

Biopsies from rectus abdominis were obtained from 22 renal failure patients (RFPs) undergoing surgical Tenchkoff catheter implantation for peritoneal dialysis and 20 control subjects undergoing elective abdominal surgery. Histochemical staining of frozen sections and morphometric analysis was used to estimate the proportion of each fibre type, muscle fibre area and capillary density. Myosin heavy chain composition was examined by SDS-PAGE.

RESULTS

There were no differences in fibre type distribution between RFPs and controls. All RFPs showed fibre atrophy [mean cross-sectional area (CSA) 3300 +/- 1100 microm2, compared to 4100 +/- 1100 microm2 in controls (P < 0.05)]. All fibre types were smaller in mean CSA in RFPs than in controls (15, 26 and 28% for types I, IIa and IIx, respectively). These differences could not be accounted for by differences in age, gender or cardiovascular or diabetic comorbidity. Muscle fibre capillarization, expressed as capillaries per fibre or capillary contacts per fibre, was significantly less in RFPs.

CONCLUSIONS

Since a non-locomotor muscle was examined, the effects of disuse as a cause of atrophy have been minimized. It is likely, therefore, that the decreased muscle fibre CSA and capillary density of RFPs compared to controls were due predominantly to uraemia itself.

Changes in muscle morphology in dialysis patients after 6 months of aerobic exercise training

BACKGROUND

In the present study we investigated the effect of a 6-month aerobic exercise programme on the morphology of the gastrocnemius muscle of end-stage renal disease (ESRD) patients.

METHODS

Twenty-four ESRD patients volunteered to participate in the training programme and underwent muscle biopsy before training. Eighteen patients completed the training programme of whom nine agreed to a post-training biopsy (one woman and eight men, mean age 56 +/- 15 years). Data are presented for the nine subjects who were biopsied before (PRE) and after training (POST) and separately for the 15 subjects for whom we only have a biopsy before training (cross-sectional group).

RESULTS

There were no significant differences (P > 0.05) in fibre type distribution or myosin heavy chain (MyHC) expression between the cross-sectional and PRE/POST groups. The mean cross-section fibre area after training (POST) increased by 46% compared with the PRE training status (P < 0.01). The proportion of atrophic fibres decreased significantly after training in type I, IIa and IIx fibre populations (from 51 to 15%, 58 to 21% and 62 to 32%, respectively). Significant differences were also found in capillary contact per fibre (CC/F), with the muscle having 24% (P < 0.05) more CC/F compared with the PRE training status. No significant differences in cytochrome c oxidase concentration were found between the groups.

CONCLUSIONS

In conclusion, exercise appeared to be beneficial in renal rehabilitation by correcting the fibre atrophy, increasing the cross-section fibre area and improving the capillarization in the skeletal muscle of renal failure patients.

An alternative histochemical method to simultaneously demonstrate muscle nuclei and muscle fibre type

We present a modified histochemical method to examine, simultaneously, nuclei and fibre type in human skeletal muscle. The new procedure (Haem-ATPase) is based on two previously used histochemical protocols. Biopsies were obtained from the rectus abdominis muscle of patients undergoing elective abdominal surgery. Fibre type composition, cross-sectional area (CSA) and nuclei to fibre ratio (N:F) were determined from frozen sections of each biopsy. To test the validity of the new method, serial sections of each biopsy were stained separately using the standard and modified methods. No differences were found in fibre type distribution, mean-weighted CSA and N:F when comparing the modified method with the standard methods. The Haem-ATPase method was found to shrink fibre size by at least 3% ( P>0.05) compared with the established myosin acid labile method. We propose that this modified technique is suitable for initial examination of both the nuclei and fibre type in the same frozen sections of human skeletal muscle.

Reliability of indices of neuromuscular leg performance in end-stage renal failure

The purpose of this study was to examine the day-to-day reproducibility and single measurement reliability of peak force, time to half peak force and rate of force development indices of knee extension neuromuscular performance in patients with end-stage renal failure. Eleven self-selected patients (6 men, 5 women) receiving maintenance dialysis (dialysis history 67 +/- 42.8 month) completed 3 inter-day assessment sessions. Each comprised a standardized warm-up and 3 intermittent static maximal voluntary actions of the knee extensors of the preferred limb (45 degrees knee flexion angle [0 degrees = full knee extension]) using a specially-constructed dynamometer. Repeated measures ANOVA of coefficient of variation scores revealed significant differences between indices in their reproducibility across day-to-day trials. Post-hoc comparisons of group mean scores suggested that peak force (6.6 +/- 3.0%) offers significantly greater measurement reproducibility than time to half peak force (16.8 +/- 9.5%) or rate of force development (20.3 +/- 12.1%). Intraclass correlation coefficients and standard error of measurement scores showed that single-trial assessments of peak force, time to half peak force and rate of force development would demonstrate limited precision and capability to discriminate subtle intra-subject or inter-subject changes in neuromuscular performance.

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.

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 fuctional 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 - 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 188 +/- 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 119 +/- 3.5 ml kg min(-10). 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.

Low-volume exercise rehabilitation improves functional capacity and self-reported functional status of dialysis patients

OBJECTIVE

The purpose of this study was to examine the effects of a program of low-volume exercise rehabilitation on the functional capacity and self-reported functional status of nonanemic dialysis patients.

DESIGN

This was a controlled study in a clinical setting with a repeated measures design. Functional capacity and functional status were assessed before and after 12 wk of exercise rehabilitation or 12 wk of normal activity for two groups of dialysis patients.

RESULTS

Mixed-model repeated measures analysis of variance revealed significant group by time interactions characterized by improvements for the exercise rehabilitation group alone in total walk, stair-climb, and stair-descent times of 15+/-5.8%, 22+/-11%, and 18+/-12% respectively. Self-reported walking speed, walking impairment-leg weakness, and walking impairment-shortness of breath were also observed to improve significantly for the exercise rehabilitation group alone by 15+/-13%, 25+/-11%, and 28+/-16%, respectively.

CONCLUSION

Low-volume exercise rehabilitation can improve activity of daily living-related functional capacity and self-reported functional status of nonanemic dialysis patients.

Reproducibility of exercise tolerance in patients with end-stage renal disease

OBJECTIVE

To determine the interday reproducibility of peak and submaximal exercise tolerance of patients with end-stage renal disease (ESRD).

DESIGN

Repeated measures.

SETTING

Day-patient rehabilitation center.

PARTICIPANTS

Twelve consecutively presenting, self-selected patients with ESRD.

INTERVENTIONS

All patients performed peak exercise tolerance assessments on a cycle ergometer up to the point of volitional fatigue, with a 1-week interval between the 2 tests.

MAIN OUTCOME MEASURES

Cardiopulmonary, hemodynamic, and physical performance parameters were assessed at peak exercise and at the lactate threshold. Standard error of measurement, percentage coefficient of variation (CV%), intraclass correlation coefficient (ICC), and limits of agreement (LOA) were calculated to determine the reproducibility of all variables.

RESULTS

CV% (range, 5%-7%) and ICCs (range, .94 - .98) for oxygen uptake and heart rate at peak exercise and lactate threshold indicated highly acceptable levels of group mean reproducibility. LOA analysis revealed satisfactory levels of reproducibility for individual patients.

CONCLUSION

Taken together, these reproducibility data may be applied to clinical work, requiring the quantification of changes in the exercise tolerance of patients with ESRD after short-term interventions (eg, exercise training, therapeutic use of recombinant erythropoietin).

Reproducibility of blood lactate-anchored ratings of perceived exertion

This study investigated the reproducibility of blood lactate-anchored ratings of perceived exertion (RPE) in seven women of average, and seven of above average cardiorespiratory fitness, [moderate and high maximal oxygen uptake (Mod VO2max and High VO2max, respectively)]. The subjects completed a series of four exercise tests, comprising a VO2max assessment and three O-grade, velocity-incremental, treadmill-running RPE estimation trials. The results revealed no significant between-group differences in RPE at the blood lactate concentration threshold (LT), and at reference levels of 2, 2.5 or 4 mmol x l(-1) (RPELT, RPE2, RPE2.5 and RPE4, respectively). The RPELT, RPE2, RPE2.5 and RPE4 were characterised by intra-class correlation coefficients of 0.97, 0.97, 0.97, 0.72 and 0.83, 0.96, 0.96, 0.90, in the High VO2max and Mod VO2max groups, respectively. The SEM% (95% confidence limits computed as a percentage of the group mean score) largely mirrored the trend in reliability with the highest values observed for RPELT in the Mod VO2max group and RPE4 in the High VO2max group. The Spearman-Brown prediction equation indicated that fixed blood lactate concentrations of 2, 2.5 and 4 mmol x l(-1) offer acceptable practical utility as potential perceptual anchor points for both groups, requiring one trial only to achieve a measurement error of less than +/- 6%.

Development of a walking test for the assessment of functional capacity in non-anaemic maintenance dialysis patients

BACKGROUND

Walk tests may be useful adjuncts or even alternatives to the assessment of peak oxygen uptake (VO2 peak) in patients with low functional capacity. Walk tests are easy to administer, appear to be well tolerated by patients and may represent a more meaningful measure for a patient group as they assess capability as well as fitness. However, the use of walk tests for the assessment of functional capacity in maintenance dialysis patients has received scant attention. The aim of this study was to assess the validity of a walking-stair-climbing test to predict VO2 peak in non-anaemic maintenance dialysis patients.

METHODS

In the validation phase of the study, 14 subjects completed a cycle ergometer-graded exercise test (GXT) for the determination of VO2 peak and a walking-stair-climbing task (WALK), each separated by a period of 7 days. Three weeks later, 18 subjects completed two WALK tests, each separated by a period of at least 48 h, to facilitate reliability estimation. Estimates of differentiated and undifferentiated ratings of perceived exertion (RPE) were obtained during and immediately consequent to all exercise tests.

RESULTS

VO2 peak (ml kg min) was significantly correlated with total WALK time (s) (r = -0.83; P < 0.001). VO2 peak (ml/kg/min) could be predicted from total WALK time with a standard error of prediction of 11%. Reliability assessment revealed no significant differences for any aspect of the WALK test performance, with intraclass correlation coefficients ranging from r = 0.71 (RPElegs) to 0.96 (total WALK time).

CONCLUSION

These results indicate that the WALK test is a valid, reliable and potentially useful method by which to assess the functional capacity of non-anaemic maintenance dialysis patients.

Prolonged intermittent high intensity exercise impairs neuromuscular performance of the knee flexors

This study investigated the effect of prolonged intermittent high intensity exercise upon the isokinetic leg strength and electromechanical delay of the knee flexors. Seven male collegiate soccer players were exposed to: (i) a prolonged intermittent high intensity exercise task (PIHIET) which required subjects to complete a single-leg pedalling task, with the preferred limb, (75 rpm for all constant-load portions of the task) consisting of 48 x 1.8 minute cycles of exercise, and (ii) a control task consisting of no exercise. Pre-, mid- and post-PIHIET gravity corrected indices of knee flexion angle-specific torque (0.44 rad knee flexion (AST); 0 rad=full knee extension; [1.05 rad x s(-1)]) were made for both intervention and control limbs. Electromechanical delay (EMD) of the m. biceps femoris during supine knee flexion movements was evaluated in the preferred leg on both intervention and control days. Repeated measures ANOVAs revealed significant condition (intervention; control) by time (pre; mid; post) interactions for both knee flexor AST (F[2,12]=4.8; p < 0.03) and EMD (F[2,12]=4.1; p < 0.05). AST was observed to decrease by 16% and EMD increase by 30% pre to post intervention. These observations suggest an impairment of neuromuscular control and the ability to maintain force generation in the knee flexors, near the extremes of the range of motion during prolonged intermittent high-intensity exercise activities. Changes of this magnitude may pose a threat to the integrity of the knee joint.