Effects of two types of training on pulmonary and cardiac responses to moderate exercise in patients with COPD

Physiological Changes Differ between Responders and Nonresponders to Pulmonary Rehabilitation in COPD

PURPOSE

Not all patients with chronic obstructive pulmonary disease (COPD) experience similar benefits after pulmonary rehabilitation (PR). This pre-post PR study used a large sample of patients with COPD to determine whether PR-induced changes of oxygen uptake (V˙O2) kinetics and exercise responses of V˙O2, carbon dioxide output (V˙CO2), minute ventilation (V˙E), V˙E/V˙CO2, breathing frequency, and tidal volume differed between responders and nonresponders to PR.

METHODS

Responders to PR were defined as patients with a minimal clinically important increase in endurance time of 105 s. Isotime (=180 s) values of V˙O2, V˙CO2, V˙E, V˙E/V˙CO2, breathing frequency, and tidal volume; gains of V˙O2, V˙CO2, and V˙E; and V˙O2 mean response time of 183 patients with COPD (forced expiratory volume in 1 s: 56% ± 19% predicted) were compared between pre- and post-PR constant work rate tests.

RESULTS

After PR, only the group of responders significantly decreased V˙O2 mean response time (P < 0.05), V˙CO2 gain, V˙E gain, and isotime values of V˙CO2, V˙E, and V˙E/V˙CO2 (all, P < 0.001), while also improving their breathing pattern (e.g., decreased breathing frequency isotime value; P < 0.0001). These changes were not observed in the group of nonresponders. Changes in physiological exercise responses were correlated with changes in physical performance (e.g., correlation between changes in V˙O2 mean response time and endurance time: P = 0.0002, r = -0.32).

CONCLUSIONS

PR-induced changes in physiological exercise responses differed between responders and nonresponders. Physiological changes are relevant to explain the variable improvements of physical performance after PR in patients with COPD.

Kinetic analyses as a tool to examine physiological exercise responses in a large sample of patients with COPD

Kinetic features such as oxygen uptake (V̇o₂) mean response time (MRT), and gains of V̇o₂, carbon dioxide output (V̇co₂), and minute ventilation (V̇e) can describe physiological exercise responses during a constant work rate test of patients with chronic obstructive pulmonary disease (COPD). This study aimed to establish simple guidelines that can identify COPD patients for whom kinetic analyses are (un)likely to be reliable and examined whether slow V̇o₂ responses and gains of V̇o₂, V̇co₂, and V̇e are associated with ventilatory, cardiovascular, and/or physical impairments. Kinetic features were examined for 265 COPD patients [forced expiratory volume in 1 s (FEV₁): 54 ± 19%predicted] who performed a constant work rate test (duration > 180 s) with breath-by-breath measurements of V̇o₂, V̇co₂, and V̇e. Negative/positive predictive values were used to define cutoff values of relevant clinical variables below/above which kinetic analyses are (un)likely to be reliable. Kinetic feature values were unreliable for 21% (= 56/265) of the patients and for 79% (= 19/24) of the patients with a peak work rate (WR_peak)< 45 W. Kinetic feature values were considered reliable for 94% (= 133/142) of the patients with an FEV₁ > 1.3 L. For patients exhibiting reliable kinetic feature values, V̇o₂ MRT was associated with ventilatory (e.g., FEV₁ %predicted: P < 0.001; r = -0.35) and physical (e.g., V̇o_2peak %predicted: P = 0.009; r = -0.18) impairments. Gains were mainly associated with cardiac function and ventilatory constraints, representing both response efficiency and limitation. Kinetic analyses are likely to be unreliable for patients with a WR_peak < 45 W. Whereas gains enrich analyses of physiological exercise responses, V̇o₂ MRT shows potential to serve as a motivation-independent, physiological indicator of physical performance.NEW & NOTEWORTHY A constant work rate test that is standardly performed during a prerehabilitation assessment is unable to provide reliable kinetic feature values for chronic obstructive pulmonary disease (COPD) patients with a peak work rate below 45 W. For patients suffering from less severe impairments, kinetic analyses are a powerful tool to examine physiological exercise responses. Especially oxygen uptake mean response time can serve as a motivation-independent, physiological indicator of physical performance in patients with COPD.

Box-Jenkins Transfer Function Modelling for Reliable Determination of VO2 Kinetics in Patients with COPD

Oxygen uptake (VO2) kinetics provide information about the ability to respond to the increased physical load during a constant work rate test (CWRT). Box-Jenkins transfer function (BJ-TF) models can extract kinetic features from the phase II VO2 response during a CWRT, without being affected by unwanted noise contributions (e.g., phase I contribution or measurement noise). CWRT data of 18 COPD patients were used to compare model fits and kinetic feature values between BJ-TF models and three typically applied exponential modelling methods. Autocorrelation tests and normalised root-mean-squared error values (BJ-TF: 2.8 ± 1.3%; exponential methods A, B and C: 10.5 ± 5.8%, 11.3 ± 5.2% and 12.1 ± 7.0%; p < 0.05) showed that BJ-TF models, in contrast to exponential models, could account for the most important noise contributions. This led to more reliable kinetic feature values compared to methods A and B (e.g., mean response time (MRT), BJ-TF: 74 ± 20 s; methods A-B: 100 ± 56 s–88 ± 52 s; p < 0.05). Only exponential modelling method C provided kinetic feature values comparable to BJ-TF features values (e.g., MRT: 75 ± 20 s). Based on theoretical considerations, we recommend using BJ-TF models, rather than exponential models, for reliable determinations of VO2 kinetics.

Home-Based, Moderate-Intensity Exercise Training Using a Metronome Improves the Breathing Pattern and Oxygen Saturation During Exercise in Patients With COPD

PURPOSE

One of the well-known but less-investigated effects of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD) is the change in breathing pattern toward a more efficient one (higher tidal volume [VT], lower breathing frequency). Evidence suggests this change can be obtained only with supervised, high-intensity exercise training (ExTr). However, some patients either do not have such programs available or are unable to exercise at higher intensity. We evaluated the effects of a 12-wk, moderate-intensity, home-monitored ExTr program using a metronome on the breathing pattern, oxygen saturation (SpO2), and dyspnea during exercise in patients with COPD.

METHODS

Twenty-one patients with COPD (7 female, aged 64-85 yr) performed spirometry, incremental, and endurance walking tests (at 60% of maximal walking speed) on a treadmill before and after training. During the endurance test, patients were equipped with an instrument that continuously monitored ventilation ((Equation is included in full-text article.)E), breathing pattern, and SpO2. Patients trained at home for 12 wk, 30 min/d for at least 4 d/wk at moderate intensity. A metronome paced the walking speed.

RESULTS

Sixteen patients completed the program. After training, a significant change was observed in breathing pattern (lower (Equation is included in full-text article.)E and (Equation is included in full-text article.)E/VT ratio; P < .001), a higher SpO2 (P < .001), and a lower dyspnea perception at the same work intensity (P < .01). The (Equation is included in full-text article.)E/VT ratio and SpO2 during exercise were significantly related (r = 0.56, P = .001).

CONCLUSION

A change in breathing pattern towards more efficient ventilation can be obtained with a moderate, home-monitored ExTr program with a pace that is controlled by a metronome. Decreased (Equation is included in full-text article.)E/VT was associated with an improved SpO2 during exercise.

Oxygen uptake on-kinetics before and after aerobic exercise training in individuals with traumatic brain injury

Objective: The high prevalence of fatigue among persons with traumatic brain injury (TBI) may be related to poor cardiorespiratory fitness observed in this population. Oxygen uptake on-kinetics is a method of assessing cardiorespiratory fitness and may be used to examine performance fatigability (decline in performance during a given activity) in persons with TBI.Purpose: To examine the effect of aerobic exercise training on oxygen uptake on-kinetics during treadmill walking in individuals with TBI.Methods: Seven ambulatory adults with chronic non-penetrating TBI performed short moderate-intensity (3-6 metabolic equivalents) walking bouts on a treadmill, prior to and following an aerobic exercise training program (clinicaltrials.gov: NCT01294332). The 12-week training program consisted of vigorous-intensity exercise on a treadmill for 30 min, 3 times a week. Breath-by-breath pulmonary gas exchange was measured throughout the bouts, and oxygen uptake on-kinetics described the time taken to achieve a steady-state response.Results: Faster oxygen uptake on-kinetics was observed after exercise training, for both the absolute and relative intensity as pre-training.Conclusions: Faster oxygen uptake on-kinetics following aerobic exercise training suggests an attenuated decline in physical performance during a standardized walking bout and improved performance fatigability in these individuals with TBI.Implications for rehabilitationSevere fatigue is a common complaint among persons with traumatic brain injury (TBI).Oxygen uptake on-kinetics may be used as an objective physiological measure of performance fatigability in persons with TBI.Faster oxygen uptake on-kinetics following aerobic exercise training suggests improved performance fatigability in these individuals with TBI.Aerobic exercise training appeared beneficial for reducing performance fatigability and may be considered as part of the rehabilitative strategy for those living with TBI.

Nonparametric dynamical model of cardiorespiratory responses at the onset and offset of treadmill exercises

This paper applies a nonparametric modelling method with kernel-based regularization to estimate the carbon dioxide production during jogging exercises. The kernel selection and regularization strategies have been discussed; several commonly used kernels are compared regarding the goodness-of-fit, sensitivity, and stability. Based on that, the most appropriate kernel is then selected for the construction of the regularization term. Both the onset and offset of the jogging exercises are investigated. We compare the identified nonparametric models, which include both impulse response models and step response models for the two periods, as well as the relationship between oxygen consumption and carbon dioxide production. The result statistically indicates that the steady-state gain of the carbon dioxide production in the onset of exercise is bigger than that in the offset while the response time of both onset and offset are similar. Compared with oxygen consumption, the response speed of carbon dioxide production is slightly slower in both onset and offset period while its steady-state gains are similar for both periods. The effectiveness of the kernel-based method for the dynamic modelling of cardiorespiratory response to exercise is also well demonstrated. Graphical Abstract Comparison between VO₂ and VCO₂ during onset and offset of exercise.

Pulmonary rehabilitation for COPD improves exercise time rather than exercise tolerance: effects and mechanisms

BACKGROUND

COPD patients undergoing pulmonary rehabilitation (PR) show various responses. The purpose of this study was to investigate the possible mechanisms and predictors of the response to PR in COPD patients.

METHODS

Thirty-six stable COPD patients underwent PR including a 4-week high-intensity exercise training program, and they were evaluated by cardiopulmonary exercise testing. All patients (mean age 69 years, severe and very severe COPD 94%) were classified into four groups by whether the exercise time (T_ex) or the peak oxygen uptake [Formula: see text] increased after PR: two factors increased (both the T_ex and the peak [Formula: see text] increased); two factors decreased; time only increased (the T_ex increased, but the peak [Formula: see text] economized); and [Formula: see text] only increased (the T_ex decreased, but the peak [Formula: see text] increased). Within all patients, the relationships between baseline variables and the post-to-pre-change ratio of the time-slope, T_ex/(peak minus resting [Formula: see text]), were investigated.

RESULTS

Compared with the two factors increased group (n=11), in the time only increased group (n=18), the mean differences from pre-PR at peak exercise in 1) minute ventilation [Formula: see text] (P=0.004), [Formula: see text] (P<0.0001), and carbon dioxide output [Formula: see text] (P<0.0001) were lower, 2) [Formula: see text]/ [Formula: see text] (P=0.034) and [Formula: see text]/ [Formula: see text] (P=0.006) were higher, and 3) the dead space/tidal volume ratio (V_D/V_T) and the dyspnea level were similar. After PR, there was no significant difference in the ratio of the observed peak heart rate (HR) to the predicted peak HR (220 - age [years]) between the two groups. A significant negative correlation with the baseline time-slope (r=-0.496, P=0.002) and a positive correlation with the baseline body mass index (BMI) (r=0.496, P=0.002) were obtained.

CONCLUSIONS

PR in COPD patients improves T_ex rather than exercise tolerance, economizing oxygen requirements, resulting in reduced ventilatory requirements without cardiac loads followed by reduced exertional dyspnea. In addition, the time-slope and BMI could be used to predict PR responses beforehand.

Pulmonary oxygen uptake and muscle deoxygenation kinetics during heavy intensity cycling exercise in patients with emphysema and idiopathic pulmonary fibrosis

BACKGROUND

Little is known about the mechanistic basis for the exercise intolerance characteristic of patients with respiratory disease; a lack of clearly defined, distinct patient groups limits interpretation of many studies. The purpose of this pilot study was to investigate the pulmonary oxygen uptake ([Formula: see text] O₂) response, and its potential determinants, in patients with emphysema and idiopathic pulmonary fibrosis (IPF).

METHODS

Following a ramp incremental test for the determination of peak [Formula: see text] O₂ and the gas exchange threshold, six emphysema (66 ± 7 years; FEV_1, 36 ± 16%), five IPF (65 ± 12 years; FEV₁, 82 ± 11%) and ten healthy control participants (63 ± 6 years) completed three repeat, heavy-intensity exercise transitions on a cycle ergometer. Throughout each transition, pulmonary gas exchange, heart rate and muscle deoxygenation ([HHb], patients only) were assessed continuously and subsequently modelled using a mono-exponential with ([Formula: see text] O₂, [HHb]) or without (HR) a time delay.

RESULTS

The [Formula: see text] O₂ phase II time-constant (τ) did not differ between IPF and emphysema, with both groups significantly slower than healthy controls (Emphysema, 65 ± 11; IPF, 69 ± 7; Control, 31 ± 7 s; P < 0.05). The HR τ was slower in emphysema relative to IPF, with both groups significantly slower than controls (Emphysema, 87 ± 19; IPF, 119 ± 20; Control, 58 ± 11 s; P < 0.05). In contrast, neither the [HHb] τ nor [HHb]:O₂ ratio differed between patient groups.

CONCLUSIONS

The slower [Formula: see text] O₂ kinetics in emphysema and IPF may reflect poorer matching of O₂ delivery-to-utilisation. Our findings extend our understanding of the exercise dysfunction in patients with respiratory disease and may help to inform the development of appropriately targeted rehabilitation strategies.

Is the six-minute walk test a useful tool to prescribe high-intensity exercise in patients with chronic obstructive pulmonary disease?

BACKGROUND

It is not yet completely known whether the 6MWT can be used to prescribe high-intensity exercise for patients with COPD.

OBJECTIVE

To evaluate the ability of the six-minute walk test (6MWT) to prescribe high-intensity exercise for patients with chronic obstructive pulmonary disease (COPD).

METHODS

Lung function, maximal inspiratory strength, symptoms and exercise capacity were evaluated in patients with COPD (n = 27) before and after a 12-week high-intensity exercise program. Criteria for high-intensity training were: 1) ≥75% of the 6MWT average speed; 2) American Thoracic Society/European Respiratory Society (ATS/ERS) criteria (≥60% of the maximal incremental shuttle walk test speed).

RESULTS

The 6MWT showed good positive and negative predictive values (0.69 and 0.71, respectively), and accuracy (0.70), good reliability (ICC 0.70 [95%CI 0.45-0.85]) and moderate agreement (k 0.41 [95%CI 0.13-0.67]) with the ATS/ERS criteria.

CONCLUSION

The 6MWT has good predictive ability and accuracy in relation to high-intensity exercise for patients with COPD.

Effect of exercise training on ventilatory efficiency in patients with heart disease: a review

The analysis of ventilatory efficiency in cardiopulmonary exercise testing has proven useful for assessing the presence and severity of cardiorespiratory diseases. During exercise, efficient pulmonary gas exchange is characterized by uniform matching of lung ventilation with perfusion. By contrast, mismatching is marked by inefficient pulmonary gas exchange, requiring increased ventilation for a given CO2 production. The etiology of increased and inefficient ventilatory response to exercise in heart disease is multifactorial, involving both peripheral and central mechanisms. Exercise training has been recommended as non-pharmacological treatment for patients with different chronic cardiopulmonary diseases. In this respect, previous studies have reported improvements in ventilatory efficiency after aerobic exercise training in patients with heart disease. Against this background, the primary objective of the present review was to discuss the pathophysiological mechanisms involved in abnormal ventilatory response to exercise, with an emphasis on both patients with heart failure syndrome and coronary artery disease. Secondly, special focus was dedicated to the role of aerobic exercise training in improving indices of ventilatory efficiency among these patients, as well as to the underlying mechanisms involved.

Supported self-management for patients with moderate to severe chronic obstructive pulmonary disease (COPD): an evidence synthesis and economic analysis

BACKGROUND

Self-management (SM) support for patients with chronic obstructive pulmonary disease (COPD) is variable in its coverage, content, method and timing of delivery. There is insufficient evidence for which SM interventions are the most effective and cost-effective.

OBJECTIVES

To undertake (1) a systematic review of the evidence for the effectiveness of SM interventions commencing within 6 weeks of hospital discharge for an exacerbation for COPD (review 1); (2) a systematic review of the qualitative evidence about patient satisfaction, acceptance and barriers to SM interventions (review 2); (3) a systematic review of the cost-effectiveness of SM support interventions within 6 weeks of hospital discharge for an exacerbation of COPD (review 3); (4) a cost-effectiveness analysis and economic model of post-exacerbation SM support compared with usual care (UC) (economic model); and (5) a wider systematic review of the evidence of the effectiveness of SM support, including interventions (such as pulmonary rehabilitation) in which there are significant components of SM, to identify which components are the most important in reducing exacerbations, hospital admissions/readmissions and improving quality of life (review 4).

METHODS

The following electronic databases were searched from inception to May 2012: MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Science Citation Index [Institute of Scientific Information (ISI)]. Subject-specific databases were also searched: PEDro physiotherapy evidence database, PsycINFO and the Cochrane Airways Group Register of Trials. Ongoing studies were sourced through the metaRegister of Current Controlled Trials, International Standard Randomised Controlled Trial Number database, World Health Organization International Clinical Trials Registry Platform Portal and ClinicalTrials.gov. Specialist abstract and conference proceedings were sourced through ISI's Conference Proceedings Citation Index and British Library's Electronic Table of Contents (Zetoc). Hand-searching through European Respiratory Society, the American Thoracic Society and British Thoracic Society conference proceedings from 2010 to 2012 was also undertaken, and selected websites were also examined. Title, abstracts and full texts of potentially relevant studies were scanned by two independent reviewers. Primary studies were included if ≈90% of the population had COPD, the majority were of at least moderate severity and reported on any intervention that included a SM component or package. Accepted study designs and outcomes differed between the reviews. Risk of bias for randomised controlled trials (RCTs) was assessed using the Cochrane tool. Random-effects meta-analysis was used to combine studies where appropriate. A Markov model, taking a 30-year time horizon, compared a SM intervention immediately following a hospital admission for an acute exacerbation with UC. Incremental costs and quality-adjusted life-years were calculated, with sensitivity analyses.

RESULTS

From 13,355 abstracts, 10 RCTs were included for review 1, one study each for reviews 2 and 3, and 174 RCTs for review 4. Available studies were heterogeneous and many were of poor quality. Meta-analysis identified no evidence of benefit of post-discharge SM support on admissions [hazard ratio (HR) 0.78, 95% confidence interval (CI) 0.52 to 1.17], mortality (HR 1.07, 95% CI 0.74 to 1.54) and most other health outcomes. A modest improvement in health-related quality of life (HRQoL) was identified but this was possibly biased due to high loss to follow-up. The economic model was speculative due to uncertainty in impact on readmissions. Compared with UC, post-discharge SM support (delivered within 6 weeks of discharge) was more costly and resulted in better outcomes (£683 cost difference and 0.0831 QALY gain). Studies assessing the effect of individual components were few but only exercise significantly improved HRQoL (3-month St George's Respiratory Questionnaire 4.87, 95% CI 3.96 to 5.79). Multicomponent interventions produced an improved HRQoL compared with UC (mean difference 6.50, 95% CI 3.62 to 9.39, at 3 months). Results were consistent with a potential reduction in admissions. Interventions with more enhanced care from health-care professionals improved HRQoL and reduced admissions at 1-year follow-up. Interventions that included supervised or unsupervised structured exercise resulted in significant and clinically important improvements in HRQoL up to 6 months.

LIMITATIONS

This review was based on a comprehensive search strategy that should have identified most of the relevant studies. The main limitations result from the heterogeneity of studies available and widespread problems with their design and reporting.

CONCLUSIONS

There was little evidence of benefit of providing SM support to patients shortly after discharge from hospital, although effects observed were consistent with possible improvement in HRQoL and reduction in hospital admissions. It was not easy to tease out the most effective components of SM support packages, although interventions containing exercise seemed the most effective. Future work should include qualitative studies to explore barriers and facilitators to SM post exacerbation and novel approaches to affect behaviour change, tailored to the individual and their circumstances. Any new trials should be properly designed and conducted, with special attention to reducing loss to follow-up. Individual participant data meta-analysis may help to identify the most effective components of SM interventions.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42011001588.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.

Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others.

Effective Bronchoscopic Lung Volume Reduction Accelerates Exercise Oxygen Uptake Kinetics in Emphysema

BACKGROUND

The impact of bronchoscopic lung volume reduction (BLVR) on physiologic responses to exercise in patients with advanced emphysema remains incompletely understood. We hypothesized that effective BLVR (e-BLVR), defined as a reduction in residual volume > 350 mL, would improve cardiovascular responses to exercise and accelerate oxygen uptake (Vo₂) kinetics.

METHODS

Thirty-one patients (FEV1, 36% ± 9% predicted; residual volume, 219% ± 57% predicted) underwent a constant intensity exercise test at 70% peak work rate to the limit of tolerance before and after treatment bronchoscopy (n = 24) or sham bronchoscopy (n = 7). Physiologic responses in patients who had e-BLVR (n = 16) were compared with control subjects (ineffective BLVR or sham bronchoscopy; n = 15).

RESULTS

e-BLVR reduced residual volume (-1.1 ± 0.5 L, P = .001), improved lung diffusing capacity by 12% ± 13% (P = .001), and increased exercise tolerance by 181 ± 214 s (P = .004). Vo₂ kinetics were accelerated in the e-BLVR group but remained unchanged in control subjects (Δ mean response time, -20% ± 29% vs 1% ± 25%, P = .04). Acceleration of Vo₂ kinetics was associated with reductions in heart rate and oxygen pulse response half-times by 8% (84 ± 14 to 76 ± 15 s, P = .04) and 20% (49 ± 16 to 34 ± 16 s, P = .01), respectively. There were also increases in heart rate and oxygen pulse amplitudes during the cardiodynamic phase post e-BLVR. Faster Vo₂ kinetics in the e-BLVR group were significantly correlated with reductions in residual volume (r = 0.66, P = .005) and improvements in inspiratory reserve volume (r = 0.56, P = .024) and exercise tolerance (r = 0.63, P = .008).

CONCLUSIONS

Lung deflation induced by e-BLVR accelerated exercise Vo₂ kinetics in patients with emphysema. This beneficial effect appears to be related mechanistically to an enhanced cardiovascular response to exercise, which may contribute to improved functional capacity.

[Home-based exercise training and physical activity level over one year in COPD patients]

INTRODUCTION

The aim of our study was to investigate whether exclusive home-based training was feasible and effective in COPD patients and if patients have a persistent improvement in their level of physical activity after this intervention.

METHODS

One hundred COPD patients (FEV1=42.6% predicted) first underwent 25 weekly sessions of supervised cycle ergometry training, followed by one year of monthly supervised follow-up. Six minutes walking test, endurance test, BODE index and activity monitoring were performed before, after and one year after inclusion.

RESULTS

About 80% of the patients completed the program. They improved their exercise tolerance and their daily physical activity level, even one year after inclusion. However, more severe patients did not maintain these benefits. Daily physical activity quantity was also decreased in these patients one year after inclusion.

CONCLUSION

This home-based exercise training program is feasible and effective. Improvements are sustainable for the majority of patients. However, severe patients were not able to maintain these benefits. Other exercise training strategies may have to be considered in these patients.

The influence of aerobic fitness status on ventilatory efficiency in patients with coronary artery disease

OBJECTIVE

To test the hypotheses that 1) coronary artery disease patients with lower aerobic fitness exhibit a lower ventilatory efficiency and 2) coronary artery disease patients with lower initial aerobic fitness exhibit greater improvements in ventilatory efficiency with aerobic exercise training.

METHOD

A total of 123 patients (61.0±0.7 years) with coronary artery disease were divided according to aerobic fitness status into 3 groups: group 1 (n = 34, peak VO₂<17.5 ml/kg/min), group 2 (n = 67, peak VO₂>17.5 and <24.5 ml/kg/min) and group 3 (n = 22, peak VO₂>24.5 ml/kg/min). All patients performed a cardiorespiratory exercise test on a treadmill. Ventilatory efficiency was determined by the lowest VE/VCO₂ ratio observed. The exercise training program comprised moderate-intensity aerobic exercise performed 3 times per week for 3 months. Clinicaltrials.gov: NCT02106533 RESULTS: Before intervention, group 1 exhibited both lower peak VO2 and lower ventilatory efficiency compared with the other 2 groups (p<0.05). After the exercise training program, group 1 exhibited greater improvements in aerobic fitness and ventilatory efficiency compared with the 2 other groups (group 1: ▵ = -2.5±0.5 units; group 2: ▵ = -0.8±0.3 units; and group 3: ▵ = -1.4±0.6 units, respectively; p<0.05).

CONCLUSIONS

Coronary artery disease patients with lower aerobic fitness status exhibited lower ventilatory efficiency during a graded exercise test. In addition, after 3 months of aerobic exercise training, only the patients with initially lower levels of aerobic fitness exhibited greater improvements in ventilatory efficiency.

Exercise training in pulmonary rehabilitation

Exercise training remains a cornerstone of pulmonary rehabilitation (PR) in patients with chronic respiratory disease. The choice of type of exercise training depends on the physiologic requirements and goals of the individual patient as well as the available equipment at the PR center. Current evidence suggests that, at ground walking exercise training, Nordic walking exercise training, resistance training, water-based exercise training, tai chi, and nonlinear periodized exercise are all feasible and effective in (subgroups) of patients with chronic obstructive pulmonary disease. In turn, these exercise training modalities can be considered as part of a comprehensive, interdisciplinary PR program.

Exercise limitation in IPF patients: a randomized trial of pulmonary rehabilitation

BACKGROUND

Patients with idiopathic pulmonary fibrosis (IPF) have severely limited exercise capacity due to dyspnea, hypoxemia, and abnormal lung mechanics. This pilot study was designed to determine whether pulmonary rehabilitation were efficacious in improving the 6-min walk test (6-MWT) distance, exercise oxygen uptake, respiratory muscle strength [maximum inspiratory pressure (MIP)], and dyspnea in patients with IPF. Underlying physiological mechanisms and effects of the intervention were investigated.

METHODS

Subjects were randomly assigned to a 3-month pulmonary rehabilitation program (n = 11) or to a control group (n = 10). All subjects initially underwent the 6-MWT and constant load exercise gas exchange studies.

RESULTS

Subjects in the rehabilitation group increased treadmill exercise [metabolic equivalent of task-minutes] over the first 14 sessions. Beneficial effects on physical function resulted in those who completed rehabilitation. Subjects who completed the program increased cycle ergometer time and maintained exercise oxygen consumption (exercise VO(2)) at the baseline level over 3 months, while the control group suffered a significant decrease in exercise VO(2). Rehabilitation subjects also increased their MIP. Plasma lactate doubled and brain natriuretic peptide levels increased significantly after exercise, as did the plasma amino acids glutamic acid, arginine, histidine, and methionine. These changes were associated with significant decreases in arterial oxygen saturation and increases in 15-F(2t)-isoprostanes after exercise.

CONCLUSIONS

Pulmonary rehabilitation effectively maintained exercise oxygen uptake over 3 months and lengthened constant load exercise time in patients with moderately severe IPF. Exercise endurance on cycle ergometry testing was limited by dyspnea and severe hypoxemia associated with systemic oxidant stress.

Prescribing exercise training in pulmonary rehabilitation: a clinical experience

Built around exercise training, pulmonary rehabilitation (PR) is a multidisciplinary, evidence-based, comprehensive approach to working with the patient as a whole and not just the pulmonary component of the disease. Integrated into the individualized treatment, this intervention aims to reduce symptoms, optimize functional status, increase participation in daily life, and reduce health care costs through stabilizing or reversing systemic manifestations of the disease. Although there are many other components that should be considered to manage the impairment and symptom burden, supervised exercise training is considered the cornerstone of effective pulmonary rehabilitation. This paper addresses our clinical experience at Institut universitaire de cardiologie et de pneumologie de Québec to assess and manage exercise training in line with the current recommendations and guidelines surrounding PR.

An official American Thoracic Society/European Respiratory Society statement: key concepts and advances in pulmonary rehabilitation

BACKGROUND

Pulmonary rehabilitation is recognized as a core component of the management of individuals with chronic respiratory disease. Since the 2006 American Thoracic Society (ATS)/European Respiratory Society (ERS) Statement on Pulmonary Rehabilitation, there has been considerable growth in our knowledge of its efficacy and scope.

PURPOSE

The purpose of this Statement is to update the 2006 document, including a new definition of pulmonary rehabilitation and highlighting key concepts and major advances in the field.

METHODS

A multidisciplinary committee of experts representing the ATS Pulmonary Rehabilitation Assembly and the ERS Scientific Group 01.02, "Rehabilitation and Chronic Care," determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant clinical and scientific expertise. The final content of this Statement was agreed on by all members.

RESULTS

An updated definition of pulmonary rehabilitation is proposed. New data are presented on the science and application of pulmonary rehabilitation, including its effectiveness in acutely ill individuals with chronic obstructive pulmonary disease, and in individuals with other chronic respiratory diseases. The important role of pulmonary rehabilitation in chronic disease management is highlighted. In addition, the role of health behavior change in optimizing and maintaining benefits is discussed.

CONCLUSIONS

The considerable growth in the science and application of pulmonary rehabilitation since 2006 adds further support for its efficacy in a wide range of individuals with chronic respiratory disease.

Oxygen uptake kinetics

Muscular exercise requires transitions to and from metabolic rates often exceeding an order of magnitude above resting and places prodigious demands on the oxidative machinery and O2-transport pathway. The science of kinetics seeks to characterize the dynamic profiles of the respiratory, cardiovascular, and muscular systems and their integration to resolve the essential control mechanisms of muscle energetics and oxidative function: a goal not feasible using the steady-state response. Essential features of the O2 uptake (VO2) kinetics response are highly conserved across the animal kingdom. For a given metabolic demand, fast VO2 kinetics mandates a smaller O2 deficit, less substrate-level phosphorylation and high exercise tolerance. By the same token, slow VO2 kinetics incurs a high O2 deficit, presents a greater challenge to homeostasis and presages poor exercise tolerance. Compelling evidence supports that, in healthy individuals walking, running, or cycling upright, VO2 kinetics control resides within the exercising muscle(s) and is therefore not dependent upon, or limited by, upstream O2-transport systems. However, disease, aging, and other imposed constraints may redistribute VO2 kinetics control more proximally within the O2-transport system. Greater understanding of VO2 kinetics control and, in particular, its relation to the plasticity of the O2-transport/utilization system is considered important for improving the human condition, not just in athletic populations, but crucially for patients suffering from pathologically slowed VO2 kinetics as well as the burgeoning elderly population.

Evidence-based risk assessment and recommendations for physical activity clearance: respiratory disease

The 2 most common respiratory diseases are chronic obstructive pulmonary disease (COPD) and asthma. Growing evidence supports the benefits of exercise for all patients with these diseases. Due to the etiology of COPD and the pathophysiology of asthma, there may be some additional risks of exercise for these patients, and hence accurate risk assessment and clearance is needed before patients start exercising. The purpose of this review was to evaluate the available literature regarding the risks of exercise for patients with respiratory disease and provide evidence-based recommendations to guide the screening process. A systematic review of 4 databases was performed. The literature was searched to identify adverse events specific to exercise. For COPD, 102 randomized controlled trials that involved an exercise intervention were included (n = 6938). No study directly assessed the risk of exercise, and only 15 commented on exercise-related adverse events. For asthma, 30 studies of mixed methodologies were included (n = 1278). One study directly assessed the risk of exercise, and 15 commented on exercise-related adverse events. No exercise-related fatalities were reported. The majority of adverse events in COPD patients were musculoskeletal or cardiovascular in nature. In asthma patients, exercise-induced bronchoconstriction and (or) asthma symptoms were the primary adverse events. There is no direct evidence regarding the risk of exercise for patients with COPD or asthma. However, based on the available literature, it would appear that with adequate screening and optimal medical therapy, the risk of exercise for these respiratory patients is low.

Metabolic derangements in COPD muscle dysfunction

Mitochondrial muscle alterations are common in patients with chronic obstructive pulmonary disease (COPD) and manifest mainly as decreased oxidative capacity and excessive production of reactive oxygen species (ROS). The significant loss of oxidative capacity observed in the quadriceps of COPD patients is mainly due to reduced mitochondrial content in the fibers, a finding consistent with the characteristic loss of type I fibers observed in that muscle. Decreased oxidative capacity does not directly limit maximum performance; however, it is associated with increased lactate production at lower exercise intensity and reduced endurance. Since type I fiber atrophy does not occur in respiratory muscles, the loss of such fibers in the quadriceps could be to the result of disuse. In contrast, excessive production of ROS and oxidative stress are observed in both the respiratory muscles and the quadriceps of COPD patients. The causes of increased ROS production are not clear, and a number of different mechanisms can play a role. Several mitochondrial alterations in the quadriceps of COPD patients are similar to those observed in diabetic patients, thus suggesting a role for muscle alterations in this comorbidity. Amino acid metabolism is also altered. Expression of peroxisome proliferator-activated receptor-γ coactivator-1α mRNA is low in the quadriceps of COPD patients, which could also be a consequence of type I fiber loss; nevertheless, its response to exercise is not altered. Patterns of muscle cytochrome oxidase gene activation after training differ between COPD patients and healthy subjects, and the profile is consistent with hypoxic stress, even in nonhypoxic patients.

Dynamics of chest wall volume regulation during constant work rate exercise in patients with chronic obstructive pulmonary disease

This study evaluated the dynamic behavior of total and compartmental chest wall volumes [(V CW) = rib cage (V RC) + abdomen (V AB)] as measured breath-by-breath by optoelectronic plethysmography during constant-load exercise in patients with stable chronic obstructive pulmonary disease. Thirty males (GOLD stages II-III) underwent a cardiopulmonary exercise test to the limit of tolerance (Tlim) at 75% of peak work rate on an electronically braked cycle ergometer. Exercise-induced dynamic hyperinflation was considered to be present when end-expiratory (EE) V CW increased in relation to resting values. There was a noticeable heterogeneity in the patterns of V CW regulation as EEV CW increased non-linearly in 17/30 "hyperinflators" and decreased in 13/30 "non-hyperinflators" (P < 0.05). EEV AB decreased slightly in 8 of the "hyperinflators", thereby reducing and slowing the rate of increase in end-inspiratory (EI) V CW (P < 0.05). In contrast, decreases in EEV CW in the "non-hyperinflators" were due to the combination of stable EEV RC with marked reductions in EEV AB. These patients showed lower EIV CW and end-exercise dyspnea scores but longer Tlim than their counterparts (P < 0.05). Dyspnea increased and Tlim decreased non-linearly with a faster rate of increase in EIV CW regardless of the presence or absence of dynamic hyperinflation (P < 0.001). However, no significant between-group differences were observed in metabolic, pulmonary gas exchange and cardiovascular responses to exercise. Chest wall volumes are continuously regulated during exercise in order to postpone (or even avoid) their migration to higher operating volumes in patients with COPD, a dynamic process that is strongly dependent on the behavior of the abdominal compartment.

Optimal intensity and type of leg exercise training for people with chronic obstructive pulmonary disease

BACKGROUND

Intensity of exercise is considered a key determinant of training response, however, no systematic review has investigated the effects of different levels of training intensity on exercise capacity, functional exercise capacity and health-related quality of life (HRQoL) in people with chronic obstructive pulmonary disease (COPD). As type of training (continuous or interval) may also affect training response, the effects of the type of training in COPD also require investigation.

OBJECTIVES

To determine the effects of training intensity (higher versus lower) or type (continuous versus interval training) on primary outcomes in exercise capacity and secondary outcomes in symptoms and HRQoL for people with COPD.

SEARCH METHODS

We searched for studies in any language from the Cochrane Airways Group Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, AMED, PsycINFO and PubMed. Searches were current as of June 2011.

SELECTION CRITERIA

We included randomised controlled trials comparing higher training intensity to lower training intensity or comparing continuous training to interval training in people with COPD. We excluded studies that compared exercise training with no exercise training.

DATA COLLECTION AND ANALYSIS

We pooled results of comparable groups of studies and calculated the treatment effect and 95% confidence intervals (CI) using a random-effects model. We made two separate comparisons of effects between: 1) higher and lower training intensity; 2) continuous and interval training. We contacted authors of missing data.

MAIN RESULTS

We analysed three included studies (231 participants) for comparisons between higher and lower-intensity training and eight included studies (367 participants) for comparisons between continuous and interval training. Primary outcomes were outcomes at peak exercise (peak work rate, peak oxygen consumption, peak minute ventilation and lactate threshold), at isowork or isotime, endurance time on a constant work rate test and functional exercise capacity (six-minute walk distance). When comparing higher versus lower-intensity training, the pooled primary outcomes were endurance time and six-minute walk distance. There were no significant differences in endurance time improvement (mean difference (MD) 1.07 minutes; 95% CI -1.53 to 3.67) and six-minute walk distance improvement (MD 2.8 metres; 95% CI -10.1 to 15.6) following higher or lower-intensity training. However, heterogeneity of the endurance time results between studies was significant. When comparing continuous and interval training, there were no significant differences in any of the primary outcomes, except for oxygen consumption at isotime (MD 0.08; 95% CI 0.01 to 0.16) but the treatment effect was not considered clinically important. According to the GRADE system, studies were of low to moderate quality.

AUTHORS' CONCLUSIONS

Comparisons between the higher and lower training intensity were limited due to the small number of included studies and participants. Consequently, there are insufficient data to draw any conclusions on exercise capacity, symptoms and HRQoL for this comparison. For comparisons between continuous and interval training, both appear to be equally effective in improving exercise capacity, symptoms and HRQoL.

Effect of heliox on heart rate kinetics and dynamic hyperinflation during high-intensity exercise in COPD

Respiratory mechanical abnormalities in patients with chronic obstructive pulmonary disease (COPD) may impair cardiodynamic responses and slow down heart rate (HR) kinetics compared with normal resulting in reduced convective oxygen delivery during exercise. We reasoned that heliox breathing (79% helium-21% oxygen) and the attendant reduction of operating lung volumes should accelerate HR kinetics in the transition from rest to high-intensity exercise. Eleven male ambulatory patients with clinically stable COPD undertook constant work-rate cycle testing at 80% of each individuals' maximum work capacity while breathing room air (RA) or heliox (HX), randomly. Mean response time (MRT) for HR and dynamic end-expiratory lung volume (EELV) were measured. Resting EELV was not affected by HX breathing, while exercise EELV decreased significantly by 0.23 L at isotime during HX breathing compared with RA. During HX breathing, MRT for HR significantly accelerated (p = 0.002) by an average of 20 s (i.e., 17%). Speeded MRT for HR correlated with indices of reduced lung hyperinflation, such as EELV at isotime (r = 0.88, p = 0.03), and with improved exercise endurance time (r = -0.64, p = 0.03). The results confirm that HX-induced reduction of dynamic lung hyperinflation is associated with consistent improvement in indices of cardio-circulatory function such as HR kinetics in the rest-to-exercise transition in COPD patients.

Oxygen uptake kinetics during exercise in adults with Down syndrome

Persons with Down syndrome (DS) have diminished submaximal and peak work capacity. This study evaluated the dynamic response of oxygen uptake at onset and recovery (VO(2) kinetics) of constant-load exercise (moderate intensity 45% VO(2peak)) in adults with DS. A total of 27 healthy participants aged 18-50 years performed graded treadmill exercise to assess peak VO(2): 14 with DS (9 males and 5 females) and 13 controls without disabilities (9 males and 4 females). Subjects also performed constant-load exercise tests at 45% VO(2peak) to determine VO(2) on-transient and VO(2) off-transient responses. Peak VO(2) was lower in participants with DS as compared to controls (DS 30.2 ± 7.1; controls 46.1 ± 9.6 mL kg(-1) min(-1), P < 0.05). In contrast, at 45% VO(2peak), the time constants for the VO(2) on-transients (DS 34.6 ± 9.1; controls 37.6 ± 9.0 s) and VO(2) off-transients (DS 36.5 ± 12.3; controls 37.7 ± 7.0 s) were not significantly different between the groups. Additionally, there were no differences between on-transient and off-transient time constants in participants with DS or controls. These data demonstrate that the VO(2) kinetics at onset and recovery of moderate intensity exercise is similar between adults with DS and controls. Therefore, the submaximal exercise performance of these individuals is not affected by slowed VO(2) kinetics.

Bronchodilator effect on ventilatory, pulmonary gas exchange, and heart rate kinetics during high-intensity exercise in COPD

Respiratory mechanical abnormalities in patients with chronic obstructive pulmonary disease (COPD) may impair cardiodynamic responses and convective oxygen delivery during exercise, resulting in slower ventilatory, pulmonary gas exchange (PGE), and heart rate (HR) kinetics compared with normal. We reasoned that bronchodilators and the attendant reduction of operating lung volumes should accelerate ventilatory, PGE, and HR kinetics in the transition from rest to high-intensity exercise. Twelve clinically stable COPD patients undertook constant-work rate cycle testing at 75% of each individual's maximum work capacity after receiving either combined nebulized bronchodilators (BD) or placebo (PL), randomly. Mean response time (MRT) and amplitude of slow component for oxygen uptake (V'O(2)), carbon dioxide production (V'CO(2)), ventilation (V'(E)), and HR together with operating dynamic end-expiratory lung volume (EELV) were measured. Resting and exercise EELV decreased significantly by 0.38 L after BD compared with PL. After BD, V'O(2), V'CO(2), V'(E), and HR MRT accelerated (p < 0.05) by an average of 12, 22, 27, and 22 s, respectively (i.e., 15, 18, 22 and 27%, respectively). The slow component for V'O(2) declined by an average of 55 ml/min compared with PL. Speeded MRT for V'O(2) correlated with indices of reduced lung hyperinflation, such as resting EELV (r = -0.64, p = 0.025) and EELV at isotime (r = -0.77, p = 0.0032). The results confirm an important interaction between abnormal dynamic respiratory mechanics and indices of cardio-circulatory function in the rest-to-exercise transition in COPD patients.

Kinetics of muscle deoxygenation are accelerated at the onset of heavy-intensity exercise in patients with COPD: relationship to central cardiovascular dynamics

Patients with chronic obstructive pulmonary disease (COPD) have slowed pulmonary O2 uptake (V̇o2p) kinetics during exercise, which may stem from inadequate muscle O2 delivery. However, it is currently unknown how COPD impacts the dynamic relationship between systemic and microvascular O2 delivery to uptake during exercise. We tested the hypothesis that, along with slowed V̇o2p kinetics, COPD patients have faster dynamics of muscle deoxygenation, but slower kinetics of cardiac output (Q̇t) following the onset of heavy-intensity exercise. We measured V̇o2p, Q̇t (impedance cardiography), and muscle deoxygenation (near-infrared spectroscopy) during heavy-intensity exercise performed to the limit of tolerance by 10 patients with moderate-to-severe COPD and 11 age-matched sedentary controls. Variables were analyzed by standard nonlinear regression equations. Time to exercise intolerance was significantly ( P < 0.05) lower in patients and related to the kinetics of V̇o2p ( r = −0.70; P < 0.05). Compared with controls, COPD patients displayed slower kinetics of V̇o2p (42 ± 13 vs. 73 ± 24 s) and Q̇t (67 ± 11 vs. 96 ± 32 s), and faster overall kinetics of muscle deoxy-Hb (19.9 ± 2.4 vs. 16.5 ± 3.4 s). Consequently, the time constant ratio of O2 uptake to mean response time of deoxy-Hb concentration was significantly greater in patients, suggesting a slower kinetics of microvascular O2 delivery. In conclusion, our data show that patients with moderate-to-severe COPD have impaired central and peripheral cardiovascular adjustments following the onset of heavy-intensity exercise. These cardiocirculatory disturbances negatively impact the dynamic matching of O2 delivery and utilization and may contribute to the slower V̇o2p kinetics compared with age-matched controls.

Pulmonary rehabilitation in chronic obstructive pulmonary disease

Pulmonary rehabilitation, a multidisciplinary and structured intervention for patients with chronic pulmonary diseases, has been shown to improve exercise tolerance, reduce dyspnea and improve health-related quality of life. Pulmonary rehabilitation appears to be cost-effective, since it reduces health care utilization. Exercise training represents the cornerstone of every pulmonary rehabilitation program. To obtain clinically relevant effects, training should closely supervised, of high intensity, lasting 30-45 min for at least 3 days/week. Patients should undertake a minimum of 20 sessions, but longer programs result in larger and more long-lasting effects. Education and self-management programs have been shown to result in a substantial reduction in hospital admissions. Nutritional intervention should be considered for patients who are underweight or those with body composition abnormalities. Patients reporting fear and anxiety may benefit from psychosocial support, and the integration of occupational therapy in a pulmonary rehabilitation program can improve independence in activity. Multidisciplinary pulmonary rehabilitation is preferably implemented in an outpatient hospital- or community-based setting. Inpatient programs are suited for patients with limited transportation capabilities or severe deconditioning. The most convincing effects of home-based rehabilitation are in maintaining the improvements obtained in an outpatient setting.

Impact of diabetes, chronic heart failure, congenital heart disease and chronic obstructive pulmonary disease on acute and chronic exercise responses

Several chronic diseases are known to negatively affect the ability of an individual to perform exercise. However, the altered exercise capacity observed in these patients is not solely associated with the heart and lungs dysfunction. Exercise has also been shown to play an important role in the management of several pathologies encountered in the fields of cardiology and pneumology. Studies conducted in our institution regarding the influence of diabetes, chronic heart failure, congenital heart disease and chronic pulmonary obstructive disease on the acute and chronic exercise responses, along with the beneficial effects of exercise training in these populations, are reviewed.

Correlates of pedometer use: results from a community-based physical activity intervention trial (10,000 Steps Rockhampton)

BACKGROUND

Pedometers have become common place in physical activity promotion, yet little information exists on who is using them. The multi-strategy, community-based 10,000 Steps Rockhampton physical activity intervention trial provided an opportunity to examine correlates of pedometer use at the population level.

METHODS

Pedometer use was promoted across all intervention strategies including: local media, pedometer loan schemes through general practice, other health professionals and libraries, direct mail posted to dog owners, walking trail signage, and workplace competitions. Data on pedometer use were collected during the 2-year follow-up telephone interviews from random population samples in Rockhampton, Australia, and a matched comparison community (Mackay). Logistic regression analyses were used to determine the independent influence of interpersonal characteristics and program exposure variables on pedometer use.

RESULTS

Data from 2478 participants indicated that 18.1% of Rockhampton and 5.6% of Mackay participants used a pedometer in the previous 18-months. Rockhampton pedometer users (n = 222) were more likely to be female (OR = 1.59, 95% CI: 1.11, 2.23), aged 45 or older (OR = 1.69, 95% CI: 1.16, 2.46) and to have higher levels of education (university degree OR = 4.23, 95% CI: 1.86, 9.6). Respondents with a BMI > 30 were more likely to report using a pedometer (OR = 1.68, 95% CI: 1.11, 2.54) than those in the healthy weight range. Compared with those in full-time paid work, respondents in 'home duties' were significantly less likely to report pedometer use (OR = 0.18, 95% CI: 0.06, 0.53). Exposure to individual program components, in particular seeing 10,000 Steps street signage and walking trails or visiting the website, was also significantly associated with greater pedometer use.

CONCLUSION

Pedometer use varies between population subgroups, and alternate strategies need to be investigated to engage men, people with lower levels of education and those in full-time 'home duties', when using pedometers in community-based physical activity promotion initiatives.

Reproducibility of onset and recovery oxygen uptake kinetics in moderately impaired patients with chronic heart failure

Oxygen (O₂) kinetics reflect the ability to adapt to or recover from exercise that is indicative of daily life. In patients with chronic heart failure (CHF), parameters of O₂ kinetics have shown to be useful for clinical purposes like grading of functional impairment and assessment of prognosis. This study compared the goodness of fit and reproducibility of previously described methods to assess O₂ kinetics in these patients. Nineteen CHF patients, New York Heart Association class II–III, performed two constant-load tests on a cycle ergometer at 50% of the maximum workload. Time constants of O₂ onset- and recovery kinetics (τ) were calculated by mono-exponential modeling with four different sampling intervals (5 and 10 s, 5 and 8 breaths). The goodness of fit was expressed as the coefficient of determination (R²). Onset kinetics were also evaluated by the mean response time (MRT). Considering O₂ onset kinetics, τ showed a significant inverse correlation with peak- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ \ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{2} $$\end{document} (R = −0.88, using 10 s sampling intervals). The limits of agreement of both τ and MRT, however, were not clinically acceptable. O₂ recovery kinetics yielded better reproducibility and goodness of fit. Using the most optimal sampling interval (5 breaths), a change of at least 13 s in τ is needed to exceed normal test-to-test variations. In conclusion, O₂ recovery kinetics are more reproducible for clinical purposes than O₂ onset kinetics in moderately impaired patients with CHF. It should be recognized that this observation cannot be assumed to be generalizable to more severely impaired CHF patients.

The impact of exercise training intensity on change in physiological function in patients with chronic obstructive pulmonary disease

Pulmonary rehabilitation incorporating exercise training is an effective method of enhancing physiological function and quality of life for patients with chronic obstructive pulmonary disease (COPD). Despite the traditional belief that exercise is primarily limited by the inability to adequately increase ventilation to meet increased metabolic demands in these patients, significant deficiencies in muscle function, oxygen delivery and cardiac function are observed that contribute to exercise limitation. Because of this multifactorial exercise limitation, defining appropriate exercise training intensities is difficult. The lack of a pure cardiovascular limitation to exercise prohibits the use of training guidelines that are based on cardiovascular factors such as oxygen consumption or heart rate. Current recommendations for exercise training intensity for patients with COPD include exercising at a 'maximally tolerable level', at an intensity corresponding with 50% of peak oxygen consumption (V-O2peak), or at 60-80% of peak power output obtained on a symptom-limited exercise tolerance test. In general, it appears that higher intensity training elicits greater physiological change than lower intensity training; however, there is no consensus as to the exercise training intensity that elicits the greatest physiological benefit while remaining tolerable to patients. The 'optimal' intensity of training likely depends upon the individual goals of each patient. If the goal is to increase the ability to sustain tasks that are currently able to be performed, lower to moderate-intensity training is likely to be sufficient. If the goal of training, however, is to increase the ability to perform tasks that are above the current level of tolerance, higher intensity training is likely to elicit greater performance increases. In order to perform higher intensity exercise, an interval training model is likely required. High-intensity interval training involves significant anaerobic energy utilisation and, therefore, may better mimic the physiological requirements of activities of daily living. Also, high-intensity interval training is tolerable to patients and may, in fact, reduce the degree of dyspnoea and dynamic hyperinflation through a reduced ventilatory demand. Another factor that will determine the optimal intensity of training is the relative contribution of ventilatory limitation to exercise tolerance. If peak exercise tolerance is limited by a patient's ability to increase ventilation, it is possible that interval training at an intensity higher than peak will elicit greater muscular adaptation than an intensity at or below peak power on an incremental exercise test. More research is required to determine the optimal training intensity for pulmonary rehabilitation patients.

Fatigue and respiratory disorders

OBJECTIVES

To analyze the factors at the origin of fatigue in respiratory disorders. To assess fatigue and its functional impact on patients affected from respiratory diseases. To evaluate the results of comprehensive care on fatigue and functional capacity.

MATERIALS AND METHODS

We systematically reviewed the literature in Medline and the Cochrane Library, using the following keywords: fatigue, respiratory disorders, questionnaire, evaluation, assessment, randomized controlled trial, meta-analysis.

RESULTS

Fatigue is a high frequency symptom (90%) and takes an important place, as much as dyspnea, in the genesis of the respiratory induced handicap. Its assessment is varied, according to the studies. It originates from multiple causes, as shown from clinical and experimental studies. The main treatment consists in rehabilitation, using physical exercises. Its efficacy is demonstrated on physical endurance, but is not clear in terms of general fatigue.

CONCLUSION

Although fatigue is very frequent complaint, along with a major disabling condition, the comprehensive assessment of fatigue, in respiratory disorders, including its physical and cognitive components, is not still really codified. Rehabilitation is the main treatment. Its efficiency has been demonstrated on the physical and functional components of fatigue. Its results on perceived fatigue remains to be evaluated.

Home versus center based physical activity programs in older adults

BACKGROUND

Physical inactivity is a leading cause of preventable death and morbidity in developed countries. In addition physical activity can potentially be an effective treatment for various medical conditions (e.g. cardiovascular disease, osteoarthritis). Many types of physical activity programs exist ranging from simple home exercise programs to intense highly supervised hospital (center) based programs.

OBJECTIVES

To assess the effectiveness of 'home based' versus 'center based' physical activity programs on the health of older adults.

SEARCH STRATEGY

The reviewers searched the Cochrane Central Register of Controlled Trials (CENTRAL) (1991-present), MEDLINE (1966-Sept 2002), EMBASE (1988 to Sept 2002), CINAHL (1982-Sept 2002), Health Star (1975-Sept 2002), Dissertation Abstracts (1980 to Sept 2002), Sport Discus (1975-Sept 2002) and Science Citation Index (1975-Sept 2002), reference lists of relevant articles and contacted principal authors where possible.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of different physical activity interventions in older adults (50 years or older) comparing a 'home based' to a 'center based' exercise program. Study participants had to have either a recognised cardiovascular risk factor, or existing cardiovascular disease, or chronic obstructive airways disease (COPD) or osteoarthritis. Cardiac and post-operative programs within one year of the event were excluded.

DATA COLLECTION AND ANALYSIS

Three reviewers selected and appraised the identified studies independently. Data from studies that then met the inclusion/exclusion criteria were extracted by two additional reviewers.

MAIN RESULTS

Six trials including 224 participants who received a 'home based' exercise program and 148 who received a 'center based' exercise program were included in this review. Five studies were of medium quality and one poor. A meta-analysis was not undertaken given the heterogeneity of these studies. CARDIOVASCULAR. The largest trial (accounting for approximately 60% of the participants) looked at sedentary older adults. Three trials looked at patients with peripheral vascular disease (intermittent claudication). In patients with peripheral vascular disease center based programs were superior to home at improving distance walked and time to claudication pain at up to 6 months. However the risk of a training effect may be high. There are no longer term studies in this population. Notably home based programs appeared to have a significantly higher adherence rate than center based programs. However this was based primarily on the one study (with the highest quality rating of the studies found) of sedentary older adults. This showed an adherence rate of 68% in the home based program at two year follow-up compared with a 36% adherence in the center based group. There was essentially no difference in terms of treadmill performance or cardiovascular risk factors between groups. CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD). Two trials looked at older adults with COPD. In patients with COPD the evidence is conflicting. One study showed similar changes in various physiological measures at 3 months that persisted in the home based group up to 18 months but not in the center based group. The other study showed significantly better improvements in physiological measures in the center based group after 8 weeks but again the possibility of a training effect is high. OSTEOARTHRITIS. No studies were found. None of the studies dealt with measures of cost, or health service utilization.

AUTHORS' CONCLUSIONS

In the short-term, center based programs are superior to home based programs in patients with PVD. There is a high possibility of a training effect however as the center based groups were trained primarily on treadmills (and the home based were not) and the outcome measures were treadmill based. There is conflicting evidence which is better in patients with COPD. Home based programs appear to be superior to center based programs in terms of the adherence to exercise (especially in the long-term).