Effect of Using a Wheeled Walker on Physical Activity and Sedentary Time in People with Chronic Obstructive Pulmonary Disease: A Randomised Cross-Over Trial.

PURPOSE: To determine the effects of providing a wheeled walker (WW) for use in the home and community, on daily physical activity (PA) and sedentary time (ST) in people with chronic obstructive pulmonary disease (COPD). METHODS: A randomised cross-over study in which participants with COPD characterised by a 6-min walk distance ≤ 450 m, who had recently finished pulmonary rehabilitation, completed two 5-week phases. During one phase, participants were provided a WW to use, whereas during the other phase, the WW was not available. The order of the phases was randomised. For the final week of each phase, measures of PA and ST were collected using wearable devices and health-related quality of life was measured using the Chronic Respiratory Disease Questionnaire (CRDQ). Wheeled walker use was also measured using an odometer attached to the device. RESULTS: 17 participants [FEV1 = median (interquartile range) 33 (25) % pred; ten males] aged mean (SD) 73 (9) years completed the study. Comparing the data collected when the WW was not available for use, the daily step count was greater (mean difference [MD] 707 steps/day (95% confidence interval [CI] 75 to 1340) and participants tended to report less dyspnoea during daily life (MD 0.5 points per item, 95% CI - 0.1 to 1.0) when WW was available. No differences were observed for ST, upright time or stepping time. The WW was used over 4504 m/week (95% CI 2746 to 6262). CONCLUSION: These data demonstrated that, when provided to selected patients with COPD, WWs increased daily step count. CLINICAL TRIAL REGISTRATION NUMBER: ACTRN12609000332224.

Australian and New Zealand Pulmonary Rehabilitation Guidelines.

BACKGROUND AND OBJECTIVE: The aim of the Pulmonary Rehabilitation Guidelines (Guidelines) is to provide evidence-based recommendations for the practice of pulmonary rehabilitation (PR) specific to Australian and New Zealand healthcare contexts. METHODS: The Guideline methodology adhered to the Appraisal of Guidelines for Research and Evaluation (AGREE) II criteria. Nine key questions were constructed in accordance with the PICO (Population, Intervention, Comparator, Outcome) format and reviewed by a COPD consumer group for appropriateness. Systematic reviews were undertaken for each question and recommendations made with the strength of each recommendation based on the GRADE (Gradings of Recommendations, Assessment, Development and Evaluation) criteria. The Guidelines were externally reviewed by a panel of experts. RESULTS: The Guideline panel recommended that patients with mild-to-severe COPD should undergo PR to improve quality of life and exercise capacity and to reduce hospital admissions; that PR could be offered in hospital gyms, community centres or at home and could be provided irrespective of the availability of a structured education programme; that PR should be offered to patients with bronchiectasis, interstitial lung disease and pulmonary hypertension, with the latter in specialized centres. The Guideline panel was unable to make recommendations relating to PR programme length beyond 8 weeks, the optimal model for maintenance after PR, or the use of supplemental oxygen during exercise training. The strength of each recommendation and the quality of the evidence are presented in the summary. CONCLUSION: The Australian and New Zealand Pulmonary Rehabilitation Guidelines present an evaluation of the evidence for nine PICO questions, with recommendations to provide guidance for clinicians and policymakers.

Physical activity patterns and clusters in 1001 patients with COPD.

We described physical activity measures and hourly patterns in patients with chronic obstructive pulmonary disease (COPD) after stratification for generic and COPD-specific characteristics and, based on multiple physical activity measures, we identified clusters of patients. In total, 1001 patients with COPD (65% men; age, 67 years; forced expiratory volume in the first second [FEV1], 49% predicted) were studied cross-sectionally. Demographics, anthropometrics, lung function and clinical data were assessed. Daily physical activity measures and hourly patterns were analysed based on data from a multisensor armband. Principal component analysis (PCA) and cluster analysis were applied to physical activity measures to identify clusters. Age, body mass index (BMI), dyspnoea grade and ADO index (including age, dyspnoea and airflow obstruction) were associated with physical activity measures and hourly patterns. Five clusters were identified based on three PCA components, which accounted for 60% of variance of the data. Importantly, couch potatoes (i.e. the most inactive cluster) were characterised by higher BMI, lower FEV1, worse dyspnoea and higher ADO index compared to other clusters ( p < 0.05 for all). Daily physical activity measures and hourly patterns are heterogeneous in COPD. Clusters of patients were identified solely based on physical activity data. These findings may be useful to develop interventions aiming to promote physical activity in COPD.

A randomised controlled trial of supplemental oxygen versus medical air during exercise training in people with chronic obstructive pulmonary disease: supplemental oxygen in pulmonary rehabilitation trial (SuppORT) (Protocol).

BACKGROUND: Oxygen desaturation during exercise is common in people with chronic obstructive pulmonary disease (COPD). The aim of the study is to determine, in people with COPD who desaturate during exercise, whether supplemental oxygen during an eight-week exercise training program is more effective than medical air (sham intervention) in improving exercise capacity and health-related quality of life both at the completion of training and at six-month follow up. METHODS/DESIGN: This is a multi-centre randomised controlled trial with concealed allocation, blinding of participants, exercise trainers and assessors, and intention-to-treat analysis. 110 people with chronic obstructive pulmonary disease who demonstrate oxygen desaturation lower than 90 % during the six-minute walk test will be recruited from pulmonary rehabilitation programs in seven teaching hospitals in Australia. People with chronic obstructive pulmonary disease on long term oxygen therapy will be excluded. After confirmation of eligibility and baseline assessment, participants will be randomised to receive either supplemental oxygen or medical air during an eight-week supervised treadmill and cycle exercise training program, three times per week for eight weeks, in hospital outpatient settings. Primary outcome measures will be endurance walking capacity assessed by the endurance shuttle walk test and health-related quality of life assessed by the Chronic Respiratory Disease Questionnaire. Secondary outcomes will include peak walking capacity measured by the incremental shuttle walk test, dyspnoea via the Dyspnoea-12 questionnaire and physical activity levels measured over seven days using an activity monitor. All outcomes will be measured at baseline, completion of training and at six-month follow up. DISCUSSION: Exercise training is an essential component of pulmonary rehabilitation for people with COPD. This study will determine whether supplemental oxygen during exercise training is more effective than medical air in improving exercise capacity and health-related quality of life in people with COPD who desaturate during exercise. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12612000395831, 5th Jan,2012.

Differences in response to pulmonary rehabilitation in idiopathic pulmonary fibrosis and chronic obstructive pulmonary disease.

BACKGROUND: The benefits of pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) are well recognized. However, whether individuals with idiopathic pulmonary fibrosis (IPF) benefit is less clear. OBJECTIVES: To evaluate the effects of pulmonary rehabilitation in subjects with IPF and compare their responses with a group of COPD subjects who underwent an identical program. METHODS: For- ty-five subjects with IPF and 45 age- and Medical Research Council grade-matched COPD subjects were recruited. Subjects completed an 8-week outpatient pulmonary rehabilitation program. Dyspnea, peripheral muscle force, exercise capacity (6-min walk distance, 6MWD), activities of daily living, and health status (36-item short-form survey, SF-36) were assessed at baseline, immediately following and at 6 months following completion of the program. RESULTS: Adherence to the program was similar in both groups. Significant improvements in dyspnea, muscle force, exercise capacity and ADL were observed in both groups (all p < 0.05); however, the magnitude of improvement in all outcomes was less in the IPF group [mean (95% CI) improvement in 6MWD, IPF 16.2 (7.1-25.4); COPD 53.1 (44.9-61.2)]. All domains of SF-36, with the exception of social function, improved (all p < 0.05) in the COPD group; however, there were no changes in SF-36 scores in the IPF group. The benefits were well maintained in the COPD group at 6 months, but, with the exception of the ADL score, the benefits were no longer present in the IPF group. CONCLUSIONS: Pulmonary rehabilitation in IPF produces only modest short-term gains in dyspnea, exercise capacity and ADL, but does not improve health status.

Increasing Walking Speed to Achieve a Pre-training Endurance Shuttle Walk Time of 5-10 min May Improve Test Responsiveness in People With Chronic Obstructive Pulmonary Disease.

PURPOSE: The endurance shuttle walk test (ESWT) was used to evaluate ground-based walking training in chronic obstructive pulmonary disease. During pre-training testing, those who walked 5-10 min on the first ESWT with minimal symptoms performed additional ESWTs at increasing speeds until they were at least moderately symptomatic and terminated the test between 5 and 10 min. This report compares participant characteristics and test responsiveness with participants grouped according to whether or not faster walking speeds were selected for the ESWT during pre-training testing. METHODS: We conducted a retrospective analysis of data collected in the intervention group during a randomized controlled trial. The intervention was supervised ground-based walking training, performed two to three times/wk, for 8-10 wk. Prior to and immediately following completion of training, participants completed the 6-min walk test (6MWT), incremental shuttle walk test (ISWT), and ESWT. RESULTS: Data were available on 77 participants (70 ± 9 yr, forced expiratory volume in the first second of expiration [FEV1] 43 ± 15 % predicted). For those whom a faster speed was selected during the pre-training ESWTs were characterized by milder dyspnea and leg fatigue on completion of the baseline 6MWT and ISWT (P < .05 for all). On training completion, the change in ESWT was greater in those for whom a faster speed was selected (376 ± 344 sec vs 176 ± 274 sec; P = .017). CONCLUSIONS: Participants who report modest symptoms on completion of the pre-training 6MWT or ISWT may achieve a long pre-training ESWT time. In this situation, repeating the pre-training ESWT at a faster walking speed to achieve an exercise time between 5 and 10 min with moderate symptoms may be advantageous.

Use of supplemental oxygen during exercise testing and training for people with chronic obstructive pulmonary disease: a survey of Australian pulmonary rehabilitation programs.

OBJECTIVES: The aims of this study were to determine, in Australian pulmonary rehabilitation programs for people with COPD: (1) whether oxygen saturation (SpO2) was monitored during exercise testing; (2) whether supplemental oxygen was available during exercise testing and/or training; (3) whether oxygen was prescribed during exercise training; and the reason for providing oxygen; (4) whether a protocol was available for supplemental oxygen prescription during exercise training. METHODS: This was a cross-sectional multi-center study using a purposed-designed survey. De-identified survey data were analyzed and the absolute number and percentage of responses were recorded for each question. RESULTS: The survey was sent to 261 pulmonary rehabilitation programs and 142 surveys (54%) were available for analysis. Oxygen saturation was monitored during exercise testing in 92% of programs. Supplemental oxygen was available in the majority of programs during exercise testing (82%) and training (84%). The rationale cited by 87 programs (73%) for prescribing oxygen during exercise training was maintaining SpO2 above a threshold ranging from SpO2 80-88%. Forty-five (32%) programs had a protocol for oxygen prescription during exercise training. CONCLUSION: While monitoring of SpO2 during exercise testing and using supplemental oxygen during testing and training is common in Australian pulmonary rehabilitation programs, few programs had a protocol in place for the prescription of supplemental oxygen for people with COPD who were not on long-term oxygen therapy. This may be due to lack of strong evidence to support the use of supplemental oxygen during exercise training.

Inspiratory muscle training for patients with chronic obstructive pulmonary disease: a practical guide for clinicians.

Reduced inspiratory muscle strength is common in people with chronic obstructive pulmonary disease (COPD) and is associated with dyspnea and decreased exercise capacity. Most studies of inspiratory muscle training (IMT) in COPD have demonstrated increased inspiratory muscle strength. Many have also shown improvements in dyspnea and exercise capacity. However, a persisting challenge when translating and applying the findings of these studies in clinical practice is the disparity in training loads, modalities, and outcomes measures used in the different studies. This commentary summarizes our clinical and research experience with a threshold IMT device with the aim of providing clinicians interested in prescribing IMT in this population with practical recommendations regarding patient selection, assessment, and implementation of training. We propose using an interval-based high-intensity threshold IMT program for people who are unable to participate fully in whole-body exercise training because of comorbidities such as severe musculoskeletal problems. Initial training loads equivalent to at least 30% of a person's maximum inspiratory pressure (PImax) are required for all people undertaking IMT. Supervision, which includes monitoring of oxygen saturation throughout the first training session, is recommended, and patients are warned to expect transient delayed-onset muscle soreness, a consequence of muscle adaptation to an unaccustomed activity. We recommend training be undertaken 3 times a week for 8 weeks, with loads progressively increased as symptoms permit. It is prudent to exclude people at risk of pneumothorax or spontaneous rib fracture. Evaluation of IMT should include measures of PImax, dyspnea, health-related quality of life, and exercise capacity.

The minimal detectable difference for endurance shuttle walk test performance in people with COPD on completion of a program of high-intensity ground-based walking.

BACKGROUND: In people with moderate-to-severe chronic obstructive pulmonary disease (COPD), the minimal detectable difference (MDD) in endurance shuttle walk test (ESWT) performance following exercise training is unclear. We sought to determine the MDD for ESWT performance following supervised ground-based walking training using anchor- and distribution-based approaches and report whether these values exceeded random variation in test performance. METHODS: Participants with COPD trained for 30-45 min, 2-3 times weekly for 8-10 weeks. The ESWT was performed before and after the training period. Immediately after training, participants rated their change in walking ability using a Global Rating of Change scale. Receiver Operating Characteristic curves were used to derive the value that best separated those who perceived their improvement in walking ability to be at least 'a little' better from 'almost the same, hardly any change'. These values were compared with those calculated using a distribution-based method. Random variation in test performance was defined as the minimal detectable change (MDC), calculated using the standard error of measurement. RESULTS: 78 participants (aged 70 ±â€¯8 yr and FEV1 43 ±â€¯15% predicted) completed the ESWT before and after training. The value that best separated those who perceived their walking ability as 'a little' better was 70 s. The 95% confidence intervals around this estimate traversed zero. The distribution-based estimate was 156 s. The MDC was 227 s. CONCLUSIONS: The MDD established using the anchor- and distribution-based approaches differed considerably. Large variation in test performance cautions against using the MDD to interpret changes in an individual. CLINICAL TRIALS REGISTRATION: Australian New Zealand Clinical Trials Registry (ACTRN12609000472279).

People With COPD Who Respond to Ground-Based Walking Training Are Characterized by Lower Pre-training Exercise Capacity and Better Lung Function and Have Greater Progression in Walking Training Distance.

PURPOSE: To investigate the characteristics that distinguish responders from nonresponders to ground-based walking training (GBWT) in people with chronic obstructive pulmonary disease (COPD). METHODS: An analysis was undertaken of data collected during a trial of GBWT in people with COPD. Responders to GBWT were defined in 2 ways: (1) improved time on the endurance shuttle walk test of ≥190 sec (criterion A); or (2) improved ability to walk, perceived by the participant to be at least "moderate" (criterion B). Differences in participant characteristics, pre-training exercise capacity, health-related quality of life, and the improvement in the distance walked during the training program were examined between responders and nonresponders. RESULTS: Of the 95 participants randomized to GBWT (age 69 ± 8 yr, forced expiratory volume in 1 sec [FEV1] % predicted = 43% ± 15%), data were available for analysis on 78 and 73 patients by criterion A and criterion B, respectively. According to criterion A, 32 (41%) participants were responders. The odds of being a responder increased with increasing FEV1 % predicted (OR = 1.2; 95% CI, 1.0-1.5, for every 5% increase) and increased with decreasing pre-training incremental shuttle walk distance (OR = 1.4; 95% CI, 1.0-1.8, for every 50-m decrement). According to criterion B, 42 (58%) participants were responders. There were no differences in characteristics or pre-training measures between the responders and nonresponders. For both criteria, responders demonstrated greater change in the distance walked during the training program (P < .05). CONCLUSION: Responders to GBWT had lower pre-training exercise capacity, had better lung function, and demonstrated greater change in the distance walked during the training program.

Estimating maximum work rate during incremental cycle ergometry testing from six-minute walk distance in patients with chronic obstructive pulmonary disease.

OBJECTIVE: To develop a predictive equation to permit estimation of the maximum work rate (Wmax) achieved during an incremental cycle ergometry test from the measurement of 6-minute walk distance (6MWD) and its derivative, 6-minute walk work, which is the product of 6MWD and body weight. DESIGN: Cross-sectional observational study. SETTING: Outpatient physiotherapy and pulmonary physiology clinics in a tertiary hospital. PARTICIPANTS: Patients (N=50; 36 men) with chronic obstructive pulmonary disease (forced expiratory volume in 1 second [FEV(1)]=37%+/-11% of predicted). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Measurements were obtained of 6MWD and Wmax achieved during a laboratory-based, symptom-limited incremental cycle ergometry test. Linear regression analyses were performed using 6MWD, height, weight, and FEV(1) and using 6-minute walk work, height, and FEV(1) to determine their contribution to Wmax and to develop predictive equations for estimating Wmax. RESULTS: The equations derived to estimate Wmax using 6MWD and 6-minute walk work, respectively, were as follows: Wmax (W)=(0.122 x 6MWD)+(72.683 x height [m])-117.109 (r(2)=.67, standard error of the estimate [SEE]=10.8W) and Wmax (W)=17.393+(1.442 x 6-minute walk work) (r(2)=.60, SEE=11.8W). CONCLUSIONS: Wmax can be estimated from equations based on measurements of 6MWD or 6-minute walk work. The estimate of Wmax derived from either equation may provide a basis on which to prescribe cycle ergometry training work rates that comply with the current guidelines for pulmonary rehabilitation.

Reduction in hospitalisation following pulmonary rehabilitation in patients with COPD.

OBJECTIVES: Pulmonary rehabilitation (PR) improves exercise capacity and health-related quality of life (HRQoL), and reduces health care utilisation. This study quantified outcomes of a PR program over a 6-year period and determined the effects of PR on hospitalisation. METHODS: Patients with chronic obstructive pulmonary disesae (COPD) who entered an 8-week outpatient PR program from 1998 to 2003 were included. Functional exercise capacity (6-minute walk distance [6MWD]) and HRQoL (Chronic Respiratory Disease Questionnaire) were measured before and following PR. The number of hospital admissions and total bed-days due to a COPD exacerbation in the 12 months before and following PR were recorded. SETTING: Physiotherapy Department, Sir Charles Gairdner Hospital, Western Australia. RESULTS: 187 (73%) of the 256 patients who entered PR completed the program. Improvements in 6MWD (404.2 +/- 114.6 m to 439.6 +/- 115.0m, P < 0.001) and HRQoL (4.1 +/- 0.9 points per item to 4.9 +/- 0.9 points per item, P < 0.001) occurred following PR. There was a 46% reduction in the number of patients admitted to hospital (71 to 38) with a COPD exacerbation and a 62% reduction in total bed-days (1131 to 432) following PR. CONCLUSION: Pulmonary rehabilitation provided in an Australian teaching hospital was associated with a reduction in COPD hospitalisation, and the resultant savings outweighed the costs of providing the program.

Walking-based activity and sedentary behavior in Saudi males with chronic obstructive pulmonary disease.

OBJECTIVES: To compare walking-based activity and sedentary behavior between males with chronic obstructive pulmonary disease (COPD) and healthy controls and to examine the association between dyspnea with time spent in walking-based activity and sedentary behavior in males with COPD. METHODS: This cross-sectional study of 30 males with COPD (age 62.0±5.0 years; forced expiratory volume in one second [FEV1] 46±15% predicted) and 29 healthy controls (age 63.0±4.3 years; FEV1 91±5% predicted) was conducted at the outpatient pulmonary clinics at King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia between February 2013 and March 2014. Walking-based activity and sedentary behavior were evaluated using an activity monitor. RESULTS: Participants with COPD spent less time engaged in walking-based activity (22±8% versus 37±7% of waking hours; p less than 0.001) and more time engaged in sedentary behavior (78±8% versus 63±6% of waking hours; p less than 0.001) than healthy controls. In males with COPD, moderate to strong associations were found between the scores of the quality and emotional response components of the Dyspnea-12 (D-12) questionnaire and time spent engaged in walking-based activity and sedentary behavior (r: ≥0.46, all p less than 0.01). CONCLUSION: Males with COPD were less active and more sedentary than healthy controls. The D-12 components were associated with walking-based activity and sedentary behavior in males with COPD.

Reliability and validity of an arabic version of the dyspnea-12 questionnaire for Saudi nationals with chronic obstructive pulmonary disease.

BACKGROUND: Dyspnea is a distressing symptom experienced by people with chronic obstructive pulmonary disease (COPD). The dyspnea-12 (D-12) questionnaire comprises of 12 items and assesses the quality of this symptom, its severity and the emotional response. The original (English) version of the D-12 is reliable and valid for the measurement of dyspnea in pulmonary diseases. AIM: To translate the D-12 into Arabic and determine whether this version is reliable and valid in Saudi nationals with COPD. METHODS: The D-12 was translated into Arabic version and reviewed by an expert panel before being back-translated into English. The Arabic version was administered to five patients with COPD to test whether it was easily understood after which a final Arabic version was produced. Thereafter, 40 patients with COPD (aged 63 ΁ 9 years; 33 [82.5%] males; forced expiratory volume in one second (FEV 1) 47 ΁ 16% predicted) completed the D-12, the COPD Assessment Test (CAT) and the Chronic Respiratory Disease Questionnaire (CRDQ). Lung function and 6-minute walk distance were also measured. The D-12 was re-administered two weeks later. RESULTS: The Arabic version of the D-12 demonstrated good reliability over the two administration (intraclass correlation coefficient = 0.94, P = 0.01). Strong associations were demonstrated between the (1) total score for the D-12 and the CAT, (2) quality sub-score of the D-12 and the CAT and (3) emotional response sub-score of the D-12 and emotional function domain of the CRDQ (r ≥ 0.6, all P < 0.01). CONCLUSION: The Arabic version of the D-12 is a reliable and valid instrument in Saudi nationals with COPD.

Physiologic responses to incremental and self-paced exercise in COPD: a comparison of three tests.

OBJECTIVES: To investigate cardiorespiratory and dyspnea responses to incremental and self-paced exercise tests in patients with COPD. DESIGN: A prospective within-subject design was used. PATIENTS: Twenty stable subjects (15 men), with a mean (+/- SD) age of 64.0 +/- 7.5 years and moderate-to-severe COPD (ie, mean FEV(1), 0.8 +/- 0.3 L and 28.9 +/- 7.9% predicted) were studied. METHODS: Each subject completed a 6-min walk test (6MWT), an incremental shuttle walking test (ISWT), and a cycle ergometer test (CET), within a 2-week period. The tests were performed at least 24 h apart. Standardized encouragement was utilized in each test with the aim of maximizing performance. Heart rate (HR) and dyspnea were measured each minute throughout the tests, and pulse oximetric saturation (Spo(2)) was measured before and immediately after each test. The distances walked in the 6MWT and ISWT were compared to peak oxygen uptake (Vo(2)) values from the CET. RESULTS: HR increased linearly with increasing workload during the CET and ISWT, but increased alinearly with a disproportionate increase early in the 6MWT. In contrast, dyspnea scores increased linearly during the 6MWT, but increased alinearly with a disproportionate increase late during the CET and ISWT. Peak HR and dyspnea were not significantly different between tests. Spo(2) was significantly lower at the end of both walking tests compared to that at the end of the CET (p < 0.001). The distance walked in both the ISWT and 6MWT were related to peak Vo(2) values on the CET (for both tests, r = 0.73; p < 0.001). CONCLUSIONS: The patterns of response in HR and dyspnea seen during the 6MWT suggest that patients with COPD titrate exertion against dyspnea to achieve a peak tolerable intensity. This strategy is not possible in an externally paced ISWT or CET. However, it is a limited strategy, with performance converging at higher workloads. Similar peak exercise responses were achieved in the 6MWT, ISWT, and CET. Greater oxygen desaturation was observed during the field walking tests, suggesting that both the ISWT and 6MWT are more sensitive than the CET in detecting exercise-induced hypoxemia and in assessing ambulatory oxygen therapy needs.

The effect of learning on ventilatory responses to inspiratory threshold loading in COPD.

BACKGROUND: Progressive threshold loading (PTL) is a common test of respiratory muscle endurance. Healthy naive subjects improve endurance with successive exposures to PTL by altering their breathing responses, thus necessitating a familiarization period before reproducible measures can be obtained. This study sought to determine whether a similar "learning effect" is evident in patients with COPD, and what the mechanism of any such effect may be. METHODS: Ten subjects with COPD (FEV1 34+/-13% predicted) underwent PTL on four occasions (>24 h apart). During PTL measurements were obtained of breathing pattern and maximum threshold pressure (Pthmax) achieved. Maximum inspiratory pressure (PImax) was measured on each occasion. RESULTS: Over the four tests PImax improved by 21+/-16% (SD) (P<0.05) and Pthmax by 32+/-21% (P<0.05) with a plateau in these measures achieved by test three. Pthmax/PImax was unchanged, being 61+/-11% at test one and 67+/-12% at test four. In contrast to healthy subjects, PTL was not associated with increased expiratory time or decreased end-expiratory lung volume. CONCLUSIONS: In contrast to PImax and Pthmax, which changed with successive tests, a single measure of the ratio Pthmax/PImax may present a useful guide to the endurance capacity of the respiratory muscles in patients with COPD.

Dyspnoea in COPD: can inspiratory muscle training help?

Chronic obstructive pulmonary disease (COPD) is a progressive, common and costly condition. Dyspnoea frequently limits activity and reduces health-related quality of life. In addition to impaired lung function, peripheral muscle deconditioning and respiratory muscle dysfunction also contribute to dyspnoea and reduced exercise capacity. Pulmonary rehabilitation using whole body exercise training improves peripheral muscle function and reduces dyspnoea but does not improve respiratory muscle function. Providing that adequate training intensities are utilised, specific loading of the inspiratory muscles with commercially available hand-held devices can improve inspiratory muscle strength and endurance. Several studies have investigated the effects of inspiratory muscle training on dyspnoea in COPD subjects. Results of these studies are conflicting, most likely reflecting methodological shortcomings including insufficient training load, insensitive outcome measures, and inadequate statistical power. This paper describes the origin of dyspnoea in COPD, with particular attention given to the role of inspiratory muscle dysfunction in its genesis and its possible amelioration through inspiratory muscle training.

A comparison of the acute haemodynamic response to aerobic and resistance exercise in subjects with exercise-induced pulmonary arterial hypertension.

BACKGROUND: Exercise-induced pulmonary arterial hypertension (EIPAH) is associated with reduced exercise capacity and abnormal central haemodynamic responses to maximal aerobic exercise. Aerobic and resistance exercise training are commonly employed to treat reduced exercise capacity; however, the haemodynamic response to aerobic and resistance exercise, at training intensities, in subjects with EIPAH is unknown. METHODS: Fourteen subjects (11 with scleroderma, 12 females) with EIPAH underwent cardiopulmonary exercise testing on a cycle ergometer, a one-repetition maximum (1RM) strength test and resistance exercise at 40% and 60% of maximum on a bilateral leg press machine. All tests were performed with a pulmonary artery catheter in situ. Haemodynamic and symptomatic responses to aerobic and resistance exercise, performed at 40% of peak oxygen consumption and 40% of 1RM, and at 60% of peak oxygen consumption and 60% of 1RM, were compared. For maximal exercise, the highest haemodynamic responses recorded during the cycling and 1RM tests were compared. RESULTS: There were no differences in haemodynamic or symptomatic responses between the two modalities of submaximal exercise. At maximal exercise, all haemodynamic and symptomatic responses were lower during resistance compared with aerobic exercise (p < 0.05). CONCLUSIONS: At the intensities studied, lower-limb resistance exercise was well tolerated and was mostly associated with similar or lower haemodynamic responses compared with aerobic exercise, in subjects with EIPAH.

Implications of exercise-induced pulmonary arterial hypertension.

PURPOSE: To characterize the hemodynamic and ventilatory responses to exercise in a group of patients with unexplained dyspnea, increased risk for pulmonary arterial hypertension (PAH), and an elevated mean pulmonary artery pressure (mPAP; >30 mm Hg) on exercise. METHODS: A total of 37 symptomatic patients at risk of PAH and 20 healthy controls underwent a cardiopulmonary exercise test and were assessed for quality of life (QOL). Patients had a pulmonary artery catheter in situ during the exercise test. RESULTS: Seventeen subjects had exercise-induced PAH (EIPAH), which we defined as mPAP ≤ 25 mm Hg at rest, and mPAP > 30 mm Hg and pulmonary artery wedge pressure <20 mm Hg on exercise. These subjects had reduced peak exercise cardiac output (72% ± 19% predicted). Further, compared with matched controls, subjects with EIPAH had reduced peak oxygen consumption (1.2 ± 0.4 vs 1.7 ± 0.5 L · min, P < 0.05), an elevated ventilatory equivalent for carbon dioxide (41.0 ± 7.3 vs 31.0 ± 2.9, P < 0.05) and reduced end-tidal carbon dioxide tension (32.6 ± 3.6 vs 39.4 ± 2.7 mm Hg, P < 0.05) at the anaerobic threshold. These exercise abnormalities were associated with impaired QOL (P < 0.05). CONCLUSIONS: Elevated pulmonary artery pressure on exercise can be associated with hemodynamic and ventilatory abnormalities typical of PAH, along with impaired exercise capacity and reduced QOL.

Six-minute walk distance in healthy Singaporean adults cannot be predicted using reference equations derived from Caucasian populations.

OBJECTIVES: The 6-min walk test (6MWT) is commonly used to assess the functional exercise capacity of individuals with cardiopulmonary disease. Recent studies have established regression equations to predict the 6-min walk distance (6MWD) in healthy Caucasian populations; however, regression equations have yet to be established for the Singaporean population. The aim of this study was to determine 6MWD in healthy Singaporeans and identify contributors to 6MWD in this population. We also compared measured 6MWD with predicted 6MWD from two regression equations derived in Caucasian subjects. METHODOLOGY: Thirty-five healthy subjects (32 Chinese, 16 men) aged between 45 and 85 years performed three walking tests using a standardized protocol. 6MWD was defined as the greatest distance achieved from the three tests. Heart rate (HR) was recorded each minute during the 6MWT. Other measurements included age, height, leg length, smoking history and self-reported physical activity. RESULTS: 6MWD was 560 +/- 105 m and was not significantly different between men and women (P = 0.19). 6MWD was related to age (r = -0.36, P = 0.03), height (r = 0.35, P = 0.04), leg length (r = 0.38, P = 0.02) and the maximum HR achieved on the 6MWT when expressed as a percentage of the predicted maximum HR (%predHRmax, r = 0.73, P < 0.001). Stepwise multiple regression analysis showed that age, height, weight and %predHRmax were independent contributors (P < 0.01) to 6MWD, explaining 78% of the variance. Predicted 6MWD using regression equations derived from Caucasian subjects exceeded measured 6MWD by more than 75 m (P < 0.001). CONCLUSIONS: This is the first study to report 6MWD for healthy Singaporeans aged 45-85 years. The regression equation developed in this study explained 78% of the variance in 6MWD. Published equations derived from Caucasian subjects overestimate 6MWD in Singaporean Chinese.