Validation of Constant Work Rate Cycling Endurance Time for Use in Chronic Obstructive Pulmonary Disease Clinical Trials.

Rationale: A COPD Foundation working group sought to identify measures of exercise endurance, a meaningful aspect of physical functioning in everyday life among patients with chronic obstructive pulmonary disease (COPD) that is not fully accepted in regulatory decision making, hampering drug development. Objectives: To demonstrate, as we previously asserted (Casaburi COPD 2022;9:252), that constant work rate cycling endurance time is an appropriate exercise endurance measure in patients with COPD. Methods: To validate this assertion, we assembled an integrated database of endurance time responses, including 8 bronchodilator (2,166 subjects) and 15 exercise training (3,488 subjects) studies (Casaburi COPD 2022;9:520). Results: Construct validity was demonstrated: 1) peak physiologic and perceptual responses were similar for constant work rate and incremental cycling; 2) after bronchodilator therapy, there were greater increases in endurance time in patients with more severe airflow limitation; 3) after exercise training, endurance time increases were similar across airflow limitation severities; and 4) there were correlations between changes in endurance time and changes in mechanistically related physiologic and perceptual variables. Test-retest reliability was demonstrated, with consistency of changes in endurance time at two time points after the intervention. Responsiveness was confirmed, with significant increases in endurance time after active (but not placebo) bronchodilator therapy, with greater increases seen with more severe airflow limitation and after exercise training. On the basis of regression analysis using multiple anchor variables, the minimum important difference for endurance time increase is estimated to be approximately 1 minute. Conclusions: Constant work rate cycling endurance time is a valid exercise endurance measure in COPD, suitable for contributing to the evaluation of treatment benefit supporting regulatory decision making and evidence-based therapeutic recommendations.

Understanding the effectiveness of different exercise training programme designs on V̇O2peak in COPD: a component network meta-analysis.

Pulmonary rehabilitation programmes including aerobic training improve cardiorespiratory fitness in patients with COPD, but the optimal programme design is unclear. We used random effects additive component network meta-analysis to investigate the relative effectiveness of different programme components on fitness measured by V̇O2peak in COPD. The included 59 studies involving 2191 participants demonstrated that V̇O2peak increased after aerobic training of at least moderate intensity with the greatest improvement seen following high intensity training. Lower limb aerobic training (SMD 0.56 95% CI 0.32;0.81, intervention arms=86) and the addition of non-invasive ventilation (SMD 0.55 95% CI 0.04;1.06, intervention arms=4) appeared to offer additional benefit but there was limited evidence for effectiveness of other exercise and non-exercise components.

Endurance Time During Constant Work Rate Cycle Ergometry in COPD: Development of an Integrated Database From Interventional Studies.

Introduction: The COPD Biomarkers Qualification Consortium (CBQC) was formed under COPD Foundation management, with the goal of qualifying biomarkers and clinical outcome assessments through established regulatory processes for chronic obstructive pulmonary disease (COPD). Within CBQC, a working group evaluated opportunities for qualification of an exercise endurance measure. In a recent publication (Chronic Obstr Pulm Dis. 2022; 9[2]:252-265), we described a conceptual framework establishing exercise endurance's direct relationship to an individual with COPD's experience of physical functioning in daily life, and that increase in exercise endurance is a patient-centered, meaningful treatment benefit. We further proposed endurance time during constant work rate cycle ergometery (CWRCE) as a useful efficacy endpoint in clinical therapeutic intervention trials. In this current publication, we describe the process of assembling an integrated database of endurance time responses to interventions in COPD. Methods: We sought participant-level data from published studies incorporating CWRCE as an outcome measure. A literature search screened 2993 publications and identified 553 studies for assessment. Two interventions had sufficient data across studies to warrant data extraction: bronchodilators and rehabilitative exercise training. Investigators were contacted and requested to provide participant-by-participant data from their published studies. Results: The final dataset included data from 8 bronchodilator studies (2166) participants and 15 exercise training studies (3488 participants). The database includes 71 variables per participant, comprising demographic, pulmonary function, and detailed physiologic response data. This paper provides a detailed description of the analysis population, while analysis supporting the validation/qualification process and addressing other scientific questions will be described in subsequent publications.

Change in V˙O2peak in Response to Aerobic Exercise Training and the Relationship With Exercise Prescription in People With COPD: A Systematic Review and Meta-analysis.

BACKGROUND: Despite the wide-ranging benefits of pulmonary rehabilitation, conflicting results remain regarding whether people with COPD can improve their peak oxygen uptake (V˙O2peak) with aerobic training. RESEARCH QUESTION: The goal of this study was to investigate the effect of aerobic training and exercise prescription on V˙O2peak in COPD. STUDY DESIGN AND METHODS: A systematic review was performed by using MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases for all studies measuring V˙O2peak prior to and following supervised lower-limb aerobic training in COPD. A random effects meta-analysis limited to randomized controlled trials comparing aerobic training vs usual care was conducted. Other study designs were included in a secondary meta-analysis and meta-regression to investigate the influence of program and patient factors on outcome. RESULTS: A total of 112 studies were included (participants, N = 3,484): 21 controlled trials (n = 489), of which 13 were randomized (n = 288) and 91 were uncontrolled (n = 2,995) studies. Meta-analysis found a moderate positive change in V˙O2peak (standardized mean difference, 0.52; 95% CI, 0.34-0.69) with the intervention. The change in V˙O2peak was positively associated with target duration of exercise session (P = .01) and, when studies > 1 year duration were excluded, greater total volume of exercise training (P = .01). Similarly, the change in V˙O2peak was greater for programs > 12 weeks compared with those 6 to 12 weeks when adjusted for age and sex. However, reported prescribed exercise intensity (P = .77), training modality (P > .35), and mode (P = .29) did not affect V˙O2peak. Cohorts with more severe airflow obstruction exhibited smaller improvements in V˙O2peak (P < .001). INTERPRETATION: Overall, people with COPD achieved moderate improvements in V˙O2peak through supervised aerobic training. There is sufficient evidence to show that programs with greater total exercise volume, including duration of exercise session and program duration, are more effective. Reduced effects in severe disease suggest alternative aerobic training methods may be needed in this population. CLINICAL TRIAL REGISTRATION: PROSPERO; No.: CRD42018099300; URL: https://www.crd.york.ac.uk/prospero/.

Neuromuscular electrostimulation for adults with chronic obstructive pulmonary disease.

BACKGROUND: In people with chronic obstructive pulmonary disease (COPD), the use of neuromuscular electrostimulation (NMES) either alone, or together with conventional exercise training, might improve the condition of the peripheral muscles, increase exercise capacity and functional performance, reduce symptoms and improve health-related quality of life (HRQoL). OBJECTIVES: To determine the effects of NMES, applied in isolation or concurrently with conventional exercise training to one or more peripheral muscles, on peripheral muscle force and endurance, muscle size, exercise capacity, functional performance, symptoms, HRQoL and adverse events in people with COPD. SEARCH METHODS: We searched the Cochrane Airways Group Specialised Register, the Physiotherapy Evidence Database, clinical trial registries and conference abstracts on 14 March 2018. SELECTION CRITERIA: Randomised controlled trials that recruited adults with COPD if they had compared outcomes between a group that received NMES and a group that received usual care or compared outcomes between a group that received NMES plus conventional exercise training and a group that participated in conventional exercise training alone. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed risk of bias using the Cochrane 'Risk of bias' tool. We expressed continuous data as either the standardised mean difference (SMD) or mean difference (MD) with the corresponding 95% confidence interval (CI). We assessed the quality of evidence using the GRADE approach. MAIN RESULTS: Nineteen studies met the inclusion criteria of which 16 contributed data on 267 participants with COPD (mean age 56 to 76 years and 67% were men). Of these 16 studies, seven explored the effect of NMES versus usual care and nine explored the effect of NMES plus conventional exercise training versus conventional exercise training alone. Six studies utilised sham stimulation in the control group. When applied in isolation, NMES produced an increase in peripheral muscle force (SMD 0.34, 95% CI 0.02 to 0.65; low-quality evidence) and quadriceps endurance (SMD 1.36, 95% CI 0.59 to 2.12; low-quality evidence) but the effect on thigh muscle size was unclear (MD 0.25, 95% CI -0.11 to 0.61; low-quality evidence). There were increases in six-minute walk distance (6MWD) (MD 39.26 m, 95% CI 16.31 to 62.22; low-quality evidence) and time to symptom limitation exercising at a submaximal intensity (MD 3.62 minutes, 95% CI 2.33 to 4.91). There was a reduction in the severity of leg fatigue on completion of an exercise test (MD -1.12 units, 95% CI -1.81 to -0.43). The increase in peak rate of oxygen uptake (VO2peak) was of borderline significance (MD 0.10 L/minute, 95% CI 0.00 to 0.19).For NMES with conventional exercise training, there was an uncertain effect on peripheral muscle force (SMD 0.47, 95% CI -0.10 to 1.04; very low-quality evidence) and there were insufficient studies to undertake a meta-analysis on the effect on quadriceps endurance or thigh muscle size. However, there was an increase in 6MWD in favour of NMES combined with conventional exercise training (MD 25.87 m, 95% CI 1.06 to 50.69; very low-quality evidence). In people admitted to either in an intensive care unit or a respiratory high dependency centre, NMES combined with conventional exercise reduced the time taken for participants to first sit out of bed by 4.98 days (95% CI -8.55 to -1.41; very low-quality evidence), although the statistical heterogeneity for this analysis was high (I2 = 60%). For both types of studies (i.e. NMES versus usual care and NMES with conventional exercise training versus conventional exercise training alone), there was no risk difference for mortality or minor adverse events in participants who received NMES. AUTHORS' CONCLUSIONS: NMES, when applied in isolation, increased quadriceps force and endurance, 6MWD and time to symptom limitation exercising at a submaximal intensity, and reduced the severity of leg fatigue on completion of exercise testing. It may increase VO2peak, but the true effect on this outcome measure could be trivial. However, the quality of evidence was low or very low due to risk of bias within the studies, imprecision of the estimates, small number of studies and inconsistency between the studies. Although there were no additional gains in quadriceps force with NMES plus conventional exercise training, there was evidence of an increase in 6MWD. Further, in people who were the most debilitated, the addition of NMES may have accelerated the achievement of a functional milestone, that is, the first time someone sits out of bed.

Gait Speed: Validity of Measurement in Patients With Severe Chronic Lung Disease, Including Prognostic and Practical Implications.

Gait speed is used increasingly to predict function and future well-being among healthy elderly people as well as for those with long-term medical conditions. When selecting outcome measures such as walking speed, it is important to include the circumstances under which the measurement is made to avoid bias and ensure accurate recommendations. We completed a retrospective chart review of walking test results from patients with chronic lung disease to demonstrate the practical implications of reporting gait speed from either a standing or walking start. In this cohort of 99 patients (55 with COPD), gait speed from a standing start underestimated usual gait speed (difference = 6.1 m/min [5.3-6.9 m/min]) with poor agreement (8 m/min [6.6-9.4 m/min]) between the two methods of reporting speed. The standing start speed incorrectly identified some patients as at higher risk for poor health. In a practical example, gait speed from a standing start produced 11 false-negative evaluations of the ability to complete a road crossing at usual speed. We present walking speeds using both methods, which illustrate the importance of construct validity and measurement protocol.

The Impact of Listening to Music During a High-Intensity Exercise Endurance Test in People With COPD.

BACKGROUND: In people with COPD, dyspnea is the primary symptom limiting exercise tolerance. One approach to reducing dyspnea during exercise is through music listening. A constant speed endurance test reflects a high-intensity aerobic exercise training session, but whether listening to music affects endurance time is unknown. This study aimed to determine the effects of listening to music during a constant speed endurance test in COPD. METHODS: Participants with COPD completed two endurance walk tests, one with and one without listening to self-selected music throughout the test. The primary outcome was the difference in endurance time between the two conditions. Heart rate, percutaneous oxygen saturation, dyspnea, and rate of perceived exertion were measured before and after each test. RESULTS: Nineteen participants (mean [SD]: age, 71 [8] years; FEV1, 47 [19] % predicted) completed the study. Endurance time was greater (1.10 [95% CI, 0.41-1.78] min) while listening to music (7.0 [3.1] min) than without (5.9 [2.6] min), and reduced end-test dyspnea (1.0 [95% CI, -2.80 to -1.80] units) (with music, 4.6 [1.7] units; vs without music, 5.6 [1.4] units, respectively). There was not a significant difference in heart rate, percutaneous oxygen saturation, or leg fatigue. There were no adverse events under either condition. CONCLUSIONS: In COPD, dyspnea was less while listening to music and was accompanied by an increased tolerance of high-intensity exercise demonstrated by greater endurance time. Practically, the effect was modest but may represent an aid for exercise training of these patients. TRIAL REGISTRY: Australian New Zealand Clinical Trials Registry; No. ACTRN12617001217392.

The effects of exercise modality and intensity on energy expenditure and cardiorespiratory response in adults with obesity and treated obstructive sleep apnoea.

To inform recommendations for the exercise component of a healthy lifestyle intervention for adults with obesity and treated obstructive sleep apnoea (OSA), we investigated the total energy expenditure (EE) and cardiorespiratory response to weight-supported (cycling) and unsupported (walking) exercise. Individuals with treated OSA and a body mass index (BMI) > 30 kg/m2 performed an incremental cardiopulmonary exercise test on a cycle ergometer and a treadmill to determine the peak oxygen uptake [Formula: see text]. Participants subsequently completed two endurance tests on each modality, matched at 80% and 60% of the highest [Formula: see text] determined by the incremental tests, to intolerance. The cardiorespiratory response was measured and total EE was estimated from the [Formula: see text]. Sixteen participants completed all six tests: mean [SD] age 57 [13] years and median [IQ range] BMI 33.3 [30.8-35.3] kg/m2. Total EE during treadmill walking was greater than cycling at both high (158 [101] vs. 29 [15] kcal; p < 0.001) and moderate (178 [100] vs. 85 [59] kcal; p = 0.002) intensities, respectively, with similar cardiorespiratory responses and pattern of EE during rest, exercise and recovery. Contrary to current guidelines, walking might be the preferred training modality to achieve the combination of weight loss and increased cardiorespiratory fitness in adults with obesity and treated OSA.

One-Legged Cycle Training for Chronic Obstructive Pulmonary Disease. A Pragmatic Study of Implementation to Pulmonary Rehabilitation.

RATIONALE: In patients with chronic obstructive pulmonary disease (COPD), partitioned exercise training using one-legged cycling leads to greater improvements in peak oxygen uptake than conventional two-legged cycling. OBJECTIVES: We evaluated the feasibility of incorporating one-legged cycling as the principal aerobic training modality for pulmonary rehabilitation in COPD. METHODS: Physiotherapists underwent four teaching sessions about the principles and practical implementation of one-legged cycling training. Patients enrolled in a pulmonary rehabilitation program underwent 6-8 weeks of training in which one-legged cycling three times per week was the principal aerobic exercise activity. Participants cycled for 15 minutes with each leg, in each session. An incremental cardiopulmonary exercise test was completed before and after pulmonary rehabilitation along with standard pulmonary rehabilitation outcome measures. Participants and physiotherapists completed a satisfaction survey at the end of the program. MEASUREMENTS AND MAIN RESULTS: A total of 22 out of 32 participants (14 male; mean [SD] age, 66 [7] years; FEV1% predicted, 32 [17]%; median [interquartile range] Medical Research Council dyspnea scale, 3.5 [3.0-4.3]) completed pulmonary rehabilitation. Peak oxygen uptake increased 1.1 (0.4-1.7) ml·min(-1)·kg(-1) (8%) from baseline (P<0.01). The mean (95% confidence interval) 6-minute-walk test distance improved by 72 (45-98) m (P=0.001). The change in the Chronic Respiratory Questionnaire total score of 1.6 (1.1-2.1; P<0.001) was achieved by improvement in all four domains above the clinically important difference. All the physiotherapists considered one-legged cycling safe and would continue to prescribe it; 75% of participants would recommend it to other patients. CONCLUSIONS: One-legged cycling was successfully implemented into a "real-life" pulmonary rehabilitation program, demonstrating improvements in cardiorespiratory fitness with associated improvement in function for patients with moderate/severe COPD. One-legged cycling should be recommended in professional pulmonary rehabilitation guidelines as an option for exercise training and be available in other pulmonary rehabilitation programs. Clinical trial registered with www.clinicaltrials.gov (NCT01930526).

Is quadriceps endurance reduced in COPD?: a systematic review.

BACKGROUND: Although the aerobic profile of the quadriceps muscle is reduced in COPD, there is conflicting evidence regarding whether this leads to reduced quadriceps muscle endurance. We, therefore, performed a systematic review of studies comparing quadriceps endurance in individuals with COPD with that in healthy control subjects. METHODS: Relevant studies were identified by searching six electronic databases (1946-2011). Full-text articles were obtained after two researchers independently reviewed the abstracts. The results were combined in a random effects meta-analysis, and metaregression models were fitted to assess the influence of the type of measurement. RESULTS: Data were extracted from 21 studies involving 728 individuals with COPD and 440 healthy control subjects. Quadriceps endurance was reduced in those with COPD compared with healthy control subjects (standardized mean difference, 1.16 [95% CI, 1.02-1.30]; P < .001) with a 44.5 s (4.5-84.5 s; P = .029) reduction in COPD (large effect size) when measured using a nonvolitional technique. The relationship between quadriceps endurance in those with COPD and control subjects did not differ when comparing nonvolitional and volitional techniques (P = .22) or when high- or low-intensity tasks (P = .44) were undertaken. CONCLUSIONS: Quadriceps endurance is reduced in individuals with COPD compared with healthy control subjects, independent of the type of task performed.

Repeatability of usual and fast walking speeds in patients with chronic obstructive pulmonary disease.

RATIONALE: Evaluation of the role of walking speeds in chronic obstructive pulmonary disease (COPD) should be preceded by an assessment of its repeatability. This study aimed to establish the repeatability of the usual (susual) and fast (sfast) walking speeds among patients with stable COPD and determine the accuracy of manual measurement. METHODS: Participants demonstrated their susual and sfast over 10 m with speed calculated using a stopwatch; the accuracy was confirmed with optical sensors. The walks were repeated after a 5-minute rest; the session was repeated on 2 subsequent days. The coefficient of repeatability (CR) was calculated for both speeds, and their stability over days was determined. RESULTS: A total of 29 participants (forced expiratory volume in 1 second (FEV1) = 43 ± 25% predicted; FEV1/forced vital capacity (FVC) = 41 ± 13%; susual = 60.3 ± 11 m·min; sfast = 74.3 ± 11.5 m·min) completed the study. The CRs for the susual and sfast were 7.5 (95% CI: 5.0-10.0) and 7.1 (95% CI: 4.8-9.4) m·min, respectively. There was a small increase in the susual (5%; P < .001) on the second trial of every day and between successive days (5%; P < .001); the sfast was not different between trials (P = .09) and increased only between day 1 and day 2 (4%; P < .0001). There was no difference between the stopwatch and the sensor determined susual (-0.5 [95% CI: -1.1 to 0.1] m·min; P = .12). The small difference (-2.1 [95% CI: -2.7 to -1.5] m·min; P = .0001) between the methods for sfast was within the CR of the sfast. CONCLUSIONS: In patients with moderate to severe COPD, repeated measures of the susual and sfast using a stopwatch support the use of these tests for simple, quick assessments of disability.

Do field walking tests produce similar cardiopulmonary demands to an incremental treadmill test in obese individuals with treated OSA?

BACKGROUND: Cardiorespiratory fitness, assessed during cardiopulmonary exercise tests by peak oxygen uptake (Vo2pk), is an independent predictor of mortality in obesity. We investigated whether Vo2pk and systemic responses measured during field walking tests were similar to those measured during an incremental treadmill test (ITMT) in obese individuals with treated OSA. METHODS: Individuals with treated OSA and a BMI > 30 kg/m2 were recruited. Participants completed an ITMT, two 6-min walk tests (6MWTs), and two incremental shuttle walk tests (ISWTs) on three separate days in a randomized order. Expired gas analysis was performed during all tests. RESULTS: The study was completed by 16 patients (nine men) (mean [SD] age, 58 [12] y; BMI, 36.1 [7.6] kg/m2). There was no difference (P = .27) in Vo2pk assessed by the ITMT and the ISWT (2,266 [478] and 2,017 [561] mL/min, respectively). The Vo2pk measured by the 6MWT (1,778 [360] mL/min) was lower than that measured by the ITMT (P < .01). The limits of agreement for Vo2pk between the ISWT and the ITM were ± 730 mL/min. Cardiorespiratory responses during the ISWT and the ITMT reflected a graded response to a peak, whereas the 6MWT demonstrated a rapid rise to a plateau. CONCLUSIONS: The ISWT can be used instead of an ITMT and in preference to the 6MWT to assess cardiorespiratory fitness for a cohort of obese people with treated OSA. However, the imprecision of the agreement in Vo2pk between the ITMT and ISWT means they cannot be used interchangeably in an individual. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01930513; www.clinicaltrials.gov.

Breathing helium-hyperoxia and tolerance of partitioned exercise in patients with COPD.

PURPOSE: Partitioning exercise by 1-legged cycling is more effective than conventional training in patients with chronic obstructive pulmonary disease. Similarly, inhaling helium-hyperoxia can extend conventional exercise tolerance. This study aimed to determine whether breathing helium-hyperoxia could increase the tolerance of a high-intensity exercise session achieved by 1-legged cycling. METHODS: Participants completed 2 high-intensity, constant power, 1-legged cycle tests to intolerance (tlimit). In a randomized order, they inspired 40% oxygen with the balance helium via mask and 1-way valve, 1-legged helium-hyperoxia (1L-HH), or room air with supplemental oxygen via a nasal cannula, 1-legged nitrogen-hyperoxia (1L-NH). We assessed quadriceps fatigue from the change in maximal voluntary contraction (FMVC) and transcutaneously stimulated twitch force (Ftwitch). RESULTS: Fifteen participants (forced expiratory volume in 1 second [SD] = 36 [18]% predicted; forced expiratory volume in 1 second/forced vital capacity = 34 [14]%; peak oxygen uptake = 12.8 [2.9] mL · kg · min) completed the study. Self-reported "leg fatigue" was a reason for stopping 25 of 30 tests. There was no significant difference in tlimit (0.2 [-1.4 to 1.8] min) between 1L-HH (12.2 [5.2] min) and 1L-NH (12.0 [4.1] min), or in FMVC measured shortly after HH and NH tests (P= .09). The Ftwitch was less after exercise (P< .05) in both conditions, without a difference between conditions (P= .46). CONCLUSIONS: Inspiring a helium-hyperoxia mixture does not increase the endurance of what would be a typical training session, breathing supplemental oxygen, of high-intensity 1-legged constant power exercise. Leg muscle fatigue was similar after 1-legged exercise with and without breathing the helium mixture.

Cardiorespiratory responses during the 6-minute walk and ramp cycle ergometer tests and their relationship to physical activity in stroke.

BACKGROUND AND OBJECTIVES: The 6-minute walk test (6MWT) is used to measure exercise capacity after stroke. We sought to compare cardiorespiratory responses during the 6MWT with responses to a ramp cycle ergometer test (CET) in community-dwelling individuals with stroke. A secondary objective was to determine the relationship between cardiorespiratory responses during each test and daily physical activity. METHODS: Participants completed 3 evaluation sessions. The CET and 6MWT were conducted in 2 separate sessions at least 72 hours apart. Participants wore a portable gas analysis unit (Cosmed K4b2), which also measured heart rate (HR) during the 6MWT. A uniaxial accelerometer (activPAL) was used to measure time spent upright (standing and stepping) over 5 days as an estimate of daily physical activity. RESULTS: Complete CET and 6MWT data were obtained for 16 participants (14 men), a mean ± standard deviation of 2.0 ± 1.1 years after stroke and 71.1 ± 9.7 years of age. Compared with the 6MWT, the CET elicited a higher VO(2peak) (P = .032), VCO(2peak) (P = .005), respiratory exchange ratio (P = .015), and self-reported perceived breathing (P < .0001) and leg heaviness (P < .0001) at test completion and a lower HR(peak) (P = .029). Except for the first minute, VO(2) during the 6MWT was, on average, 80% to 85% of VO(2peak) from the CET. Among 15 participants, average time spent upright per day was not significantly associated with 6MWT distance (r = 0.447, P = .096) or VO(2peak) from the CET (r = 0.388, P = .153). CONCLUSIONS: Exercise intensity achieved during the 6MWT appeared sufficiently high for aerobic training, assuming CET VO(2peak) accurately reflects aerobic capacity. The 6MWT may be useful for prescribing aerobic exercise poststroke.

Saving Time for Patients with Moderate to Severe COPD: Endurance Test Speed Set Using Usual and Fast Walk Speeds.

Background: For assessing the effects of interventions on exercise tolerance, the tolerable duration (tlimit) of a high-intensity constant-speed endurance test is recommended. The test intensity is determined by the test speed (stest) which should be individualized to target a tlimit of 3 to 15 minutes. We determined the accuracy of setting the stest to achieve a targeted tlimit of 3 to 15 minutes using the participant's easily measured and non-fatiguing usual (susual) and fast (sfast) walk speeds. Methods: Participants with COPD were asked to walk at their usual and fast walk speeds to establish their susual and sfast. This required that they walk for less than 1 minute. The individualized stest was calculated from a previously developed equation (0.57 x [sfast - susual]) + susual. Participants then completed a constant-speed endurance test, walking at this calculated stest to intolerance, to determine if the resultant tlimit occurred within 3 to 15 minutes. Results: Twenty-nine participants (forced expiratory volume in 1 second [FEV1] standard deviation [SD ]=43 [25] %predicted; FEV1 to forced vital capacity [FVC]ratio= 41 [13]%; susual = 57.3 [10.4] meters per minute (m·min-1 ); sfast = 71.7 [10.7] m·min-1) completed the study. During testing, 24 (83%) participants used supplemental oxygen and 16 (55%) used a walking aid. The derived stest was 65.6 [10.3] m·min-1 with the observed tlimit of 6.0 [5.0] minute. Twenty-four of 29 (83 %) endurance tests were within 3 to 15 minutes. Conclusion: Using the usual and fast walk speeds provides a simple, quick, inexpensive method for clinicians to set an acceptable endurance walk speed.

Defining hyperinflation as 'dynamic': moving toward the slope.

Measuring the severity of dynamic hyperinflation is a useful clinical approach to assess the effect of therapeutic interventions and explain their impact on exercise tolerance. Dynamic hyperinflation is typically quantified by the change in end expiratory lung volume from rest to the end of exercise. The result may be inconsistent with disease severity and does not clearly explain how exercise tolerance improves with therapy. Using a re-examination of selected studies, we suggest an operational definition of dynamic hyperinflation using the slope derived from serial measures of inspiratory capacity expressed as a linear function of ventilation that clearly differentiates whether therapies affect static or dynamic hyperinflation or affect lung volume only as a consequence of reducing ventilation. With this approach, the magnitude of the result is consistent with disease severity and is a more reliable outcome as it uses serial measures rather than a single time point estimate. The therapies re-evaluated are breathing helium or hyperoxic gas mixtures, bronchodilation and exercise training. A clear definition of dynamic hyperinflation will assist clinicians in assessing the impact of therapeutic interventions.