Ventilatory and metabolic adaptations to walking and cycling in patients with COPD

Poor cardiorespiratory fitness may be an indicator of more severe liver inflammation in non-alcoholic fatty liver disease patients

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is related to cardiovascular disease. Cardiorespiratory fitness (CRF) is an important indicator of cardiovascular health. Therefore, we aimed to evaluate the CRF of NAFLD patients.

METHODS

Cross-sectional study, including 32 patients with biopsy-proved NAFLD. The patients underwent ergometric test (ET) and six-minute walk test (6MWT) to determine CRF. The test results were compared to disease parameters and with each other.

RESULTS

Considering the ET, 20 (62.5%) patients had very poor or poor CRF, and in 12 (37.5%), it was regular or good. In the 6MWT, 13 (40.6%) individuals had poor CRF, in 12 (37.5%), it was very poor, and in seven (21.9%), regular. NAFLD activity score (NAS) ≥5 was observed in 12 (37.5%) individuals. Twelve (37.5%) patients were sedentary, 11 (34.4%), insufficiently active, and nine (28.1%), active. Obesity and liver inflammation on biopsy were associated with very poor/poor CRF. NAS ≥5 and sedentary lifestyle were independently associated with very poor/poor CRF by ET. Although mean VO2max values determined by both tests were similar, no correlation of VO2max determined by ET and 6MWT was observed, as occurred for the distance walked in 6MWT and values of metabolic equivalent (MET) determined by ET. There was no reproducibility between CRF determined by ET and 6MWT.

CONCLUSION

Most NAFLD patients had very poor or poor CRF. Severe liver injury (NAS ≥5) and sedentary lifestyle were independently associated with very poor/poor fitness, according to ET. No reproducibility was observed between the CRF defined by ET and 6MWT.

Nutritional State and COPD: Effects on Dyspnoea and Exercise Tolerance

Chronic Obstructive Pulmonary Disease (COPD) is a disease that is spreading worldwide and is responsible for a huge number of deaths annually. It is characterized by progressive and often irreversible airflow obstruction, with a heterogeneous clinical manifestation based on disease severity. Along with pulmonary impairment, COPD patients display different grades of malnutrition that can be linked to a worsening of respiratory function and to a negative prognosis. Nutritional impairment seems to be related to a reduced exercise tolerance and to dyspnoea becoming a major determinant in patient-perceived quality of life. Many strategies have been proposed to limit the effects of malnutrition on disease progression, but there are still limited data available to determine which of them is the best option to manage COPD patients. The purpose of this review is to highlight the main aspects of COPD-related malnutrition and to underline the importance of poor nutritional state on muscle energetics, exercise tolerance and dyspnoea.

Phenotyping Cardiopulmonary Exercise Limitations in Chronic Obstructive Pulmonary Disease

Background

Exercise limitation in chronic obstructive pulmonary disease (COPD) is commonly attributed to abnormal ventilatory mechanics and/or skeletal muscle function, while cardiovascular contributions remain relatively understudied. To date, the integrative exercise responses associated with different cardiopulmonary exercise limitation phenotypes in COPD have not been explored but may provide novel therapeutic utility. This study determined the ventilatory, cardiovascular, and metabolic responses to incremental exercise in patients with COPD with different exercise limitation phenotypes.

Methods

Patients with COPD (n = 95, FEV₁:23–113%pred) performed a pulmonary function test and incremental cardiopulmonary exercise test. Exercise limitation phenotypes were classified as: ventilatory [peak ventilation (V_Epeak)/maximal ventilatory capacity (MVC) ≥ 85% or MVC-V_Epeak ≤ 11 L/min, and peak heart rate (HR_peak) < 90%pred], cardiovascular (V_Epeak/MVC < 85% or MVC-V_Epeak > 11 L/min, and HR_peak ≥ 90%pred), or combined (V_Epeak/MVC ≥ 85% or MVC-V_Epeak ≤ 11 L/min, and HR_peak ≥ 90%pred).

Results

FEV₁ varied within phenotype: ventilatory (23–75%pred), combined (28–90%pred), and cardiovascular (68–113%pred). The cardiovascular phenotype had less static hyperinflation, a lower end-expiratory lung volume and larger tidal volume at peak exercise compared to both other phenotypes (p < 0.01 for all). The cardiovascular phenotype reached a higher V_Epeak (60.8 ± 11.5 L/min vs. 45.3 ± 15.5 L/min, p = 0.002), cardiopulmonary fitness (VO_2peak: 20.6 ± 4.0 ml/kg/min vs. 15.2 ± 3.3 ml/kg/min, p < 0.001), and maximum workload (103 ± 34 W vs. 72 ± 27 W, p < 0.01) vs. the ventilatory phenotype, but was similar to the combined phenotype.

Conclusion

Distinct exercise limitation phenotypes were identified in COPD that were not solely dependent upon airflow limitation severity. Approximately 50% of patients reached maximal heart rate, indicating that peak cardiac output and convective O₂ delivery contributed to exercise limitation. Categorizing patients with COPD phenotypically may aid in optimizing exercise prescription for rehabilitative purposes.

Ventilatory efficiency and its clinical and prognostic value in adults with cystic fibrosis

Cystic fibrosis, due to the absence or abnormal function of the cystic fibrosis transmembrane conductance regulator, is the most common life-limiting autosomal recessive genetic disorder among the Caucasian population. The lungs are particularly affected due to thick and tenacious mucus causing parenchymal anomalies ranging from bronchiectasis, progressive airflow limitation, respiratory infections, lung destruction and ultimately respiratory failure. Despite the remarkable advances in treatment that have greatly improved survival, most patients experience progressive exercise curtailment, with the consequence that a growing number of patients with cystic fibrosis will be referred for exercise-based evaluations in the forthcoming years. Cardiopulmonary exercise testing, in particular, is a useful tool to assess the mechanisms of exercise intolerance in individual patients that may have treatment and prognostic implications. In this review, we will focus on ventilatory efficiency and its clinical and prognostic value in adults with cystic fibrosis.

Acute effect of oxygen therapy on exercise tolerance and dyspnea perception in ILD patients

Ambulatory oxygen therapy (AOT) is commonly prescribed in Interstitial Lung Disease (ILD) patients, with the aim of reducing dyspnea and increasing exercise tolerance. Despite its frequent use and a reasonable physiological rationale, there is a lack of evidence supporting the effect of AOT on improving dyspnea during exercise. Moreover, dyspnea encompasses distinct sensory (intensity, quality) and affective (anxiety, fear) components with different underlying neurophysiological mechanisms. The aim of this study was to evaluate the effect of oxygen supplementation on exercise tolerance and dyspnea in ILD patients with exercise induced hypoxia (EIH). Forty-seven ILD patients performed a six minute walk test (6MWT) on room air (RA) and with oxygen supplementation (Ox). The 6MWT distance (6MWD) was significantly greater with oxygen supplementation (RA: 242±143 m vs Ox: 345±106 m p<0,01). With oxygen supplementation, the overall dyspnea and anxiety significantly decreased both at rest (1,1±1,4 Borg Unit (BU) vs 0,4±0,9BU , p.<0.01, and 1,1±1,6BU vs 0,5±1,3 BU, p.<0.05, respectively) and at the end of exercise (5,1±2,6 BU vs 3,7±2,5 BU, p.<0.001 and 3,4 ±2,9 vs 2,5 ±2,8, p.<0.01, respectively) despite a greater walked distance. In ILD patients with EIH, oxygen supplementation increases the exercise tolerance and reduces overall dyspnea perception and the anxiety component of breathlessness.

Exertional ventilation/carbon dioxide output relationship in COPD: from physiological mechanisms to clinical applications

There is well established evidence that the minute ventilation (V′_E)/carbon dioxide output (V′_CO2) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased V′_E/V′_CO2 reflects an enlarged physiological dead space (“wasted” ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The V′_E/V′_CO2 nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1 s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high V′_E/V′_CO2 is valuable to ascertain a role for the “lungs” in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase V′_E/V′_CO2. A high V′_E/V′_CO2 is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the V′_E/V′_CO2 should be valued in the clinical management of patients with COPD.

The minute ventilation/carbon dioxide production relationship is relevant to a number of patient-related outcomes in COPD. Minute ventilation/carbon dioxide production, therefore, should be valued in the clinical management of these patients.https://bit.ly/3df2upH

The importance of lower extremity involvement type on exercise performances, function, and quality of life in peripheral predominant forms of juvenile idiopathic arthritis

BACKGROUND

Juvenile idiopathic arthritis (JIA) can cause reduced exercise capacity, deterioration in functional activities, and poor health-related quality of life. This study aims to objectively reveal lower extremity involvement in the peripheral predominant forms of juvenile idiopathic arthritis through qualitative evaluations and to determine the effects of these involvements on exercise, function, and quality of life.

METHODS

Thirty-two patients with a history of peripheral arthritis and aged between 7 and 16 years participated in the study. Demographics, JIA subtype, disease duration, arthritis and deformities of the lower extremity, disease activity score, 6-min walk test (6MWT), cycling exercise test (CYC-E), childhood health assessment questionnaire (CHAQ), and pediatric quality of life inventory (PedsQoL) scores were recorded. In case of clinical suspicion of arthritis, an ultrasonographic examination was performed for a definitive diagnosis. Regression analyses were performed to explore the most associated lower extremity involvement and patient characteristics for each of the dependent variables including 6MWT, CYC-E, CHAQ, and PedsQoL.

RESULTS

Of the total number of patients, with a mean age of 12.91 (SD 2.37) years, 28.1% had knee arthritis, 15.6% foot arthritis, 12.5% hip arthritis, and 37.5% lower extremity deformity. The parameters that were most associated with CHAQ and PedsQoL were hip and knee arthritis, whereas CYC-E was found to be most associated with knee arthritis and height, and 6MWT was found to be most associated with hip arthritis, knee arthritis, and demographic characteristics.

CONCLUSION

This study emphasizes the importance of hip and knee arthritis, which are among the determinants of walking endurance, function, and quality of life; and knee arthritis, which is among the determinants of cycling performance in JIA with lower extremity involvement.

Ventilatory constraint is more severe in walking than cycling in patients with COPD

Due to its effectivity in assessing functional capacity and adding prognostic information to the staging of chronic obstructive pulmonary disease (COPD) patients, the 6-min walk test (6MWT) is extensively used in clinical evaluation. Currently, there is little information about the physiological response this test elicits in patients, especially when compared to cardiopulmonary exercise test (CPET). The aim of the study was to compare ventilatory and metabolic responses between these tests commonly used for the assessment of clinical outcome. A group of 20 patients with moderate to very severe COPD were tested for their pulmonary function (flow-volume curve, static lung volumes), occlusion mouth pressures and breath-by-breath measurement of flow, volumes, and oxygen (O₂) and carbon dioxide (CO₂) concentration during the 6MWT and CPET. All parameters measured during both exercise tests were assessed over the throughout of the tests and compared between each other at specified time points. Serially measured inspiratory vital capacity (IVC) decreased more rapidly and extensively during the walk-test (p ​< ​0,0001). This was accompanied by a limited increase in tidal volume (V_T) and minute ventilation (V_E), which were significantly lower in the course of the 6MWT (p ​= ​0,0003 and p ​= ​0,0097, respectively). We also noticed a significant decrease in hemoglobin oxygen saturation (SpO₂) during the 6MWT which was correlated to percent decrease in IVC (p ​= ​0,0206). Over the course of the 6MWT, oxygen consumption (VO₂) and V_T reached plateau within 2 ​min, while carbon dioxide production (VCO₂) and V_E within 3 ​min. During CPET, VO₂, VCO₂ and V_E rose continuously, while V_T reached plateau within 4 ​min. The 6MWT seems to be a rather endurance-based test associated with more pronounced dynamic lung hyperinflation and mechanical constraint of ventilation in comparison to cycling.

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Various types of exercise are tolerated differently.

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The 6MWT is, as opposed to ergometry, accompanied by a quicker increase in dynamic lung hyperinflation and desaturation.

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It seems that pedaling, as compared to walking, is the superior way of training movement for rehabilitation purposes.

Are the measurement properties of incremental exercise tests similar between patients with COPD and CHF?

We investigated whether the differences in exercise limitation between patients with chronic obstructive pulmonary disease (COPD) or chronic heart failure (CHF) affect the repeatability or responsiveness of incremental exercise tests. Patients with COPD (Medical Research Council dyspnoea grade 2-5) and patients with CHF (New York Heart Association class II-IV) performed two incremental shuttle walk tests (ISWT) following familiarisation and two incremental cycle ergometer tests (ICE) within 2 weeks. Both tests were repeated on completion of a pulmonary rehabilitation (PR) programme. One hundred and twelve patients were recruited. In response to exercise, patients with COPD were more likely than patients with CHF to have a ventilatory limitation (p < 0.001) and less likely to have a cardiovascular limitation (p < 0.001). The ISWT distance and ICE peak volume of oxygen uptake (VO₂Peak) were similarly repeatable (p = 0.11 and p = 0.47 for time and disease effect) and responsive to PR (p = 0.44 and p = 0.67) between diseases. There was no difference in repeatability or responsiveness with either a ventilatory or cardiovascular limitation to exercise (p > 0.20 for all comparisons). The coefficient of repeatability across the cohort was 60 m for the ISWT and 0.270 L/minute for ICE VO₂Peak. The minimum important difference (MID) for the ISWT in both diseases for PR was 30 m. The repeatability and responsiveness of the ISWT distance and ICE VO₂Peak are similar between patients with COPD and CHF and are unaffected by differences in exercise limitation. A change of 60 m in the ISWT or 0.270 L/minute in ICE VO₂Peak is required to be 95% certain that a true change has occurred within an individual patient. For a group of patients with either COPD or CHF, the MID for the ISWT distance is estimated to be 30 m.

Physiological rationale of commonly used clinical exercise tests

In order to measure cardiopulmonary performance for clinical and investigation purposes we need standardized tests which allow the comparison with standard values, between people, or individuals with themselves over time. The quest for the ideal exercise test has led to the development of several formats, the so called laboratory and field tests. Incremental exercise tests allow measurement of maximal exercise capacity and a host of submaximal variables of great interest. The physiological rationale of the tests and of the detection of interesting submaximal variables can be explained from the oxygen uptake and carbon dioxide output kinetic response to constant power exercise. When the muscles have to produce very high energy, the exercise is physiologically limited to relatively short duration. The minimum power at which an exercise can no longer be sustained for long periods of time is called critical power. Above critical power the time-power function shows a hyperbolic shape. This shape provides the rationale for understanding the properties, limitations and responsiveness to interventions of endurance tests such as constant power test on a cycle-ergometer or treadmill, endurance shuttle walk test and six-minute walk test.

Physiologic Effects of Oxygen Supplementation During Exercise in Chronic Obstructive Pulmonary Disease

Supplemental long-term oxygen therapy (LTOT) is a well-established therapy that improves mortality in patients with chronic obstructive pulmonary disease (COPD) with resting hypoxemia. In the large number of patients with COPD who do not have severe resting hypoxemia but who desaturate with exercise, the clinical benefits that can be obtained by supplemental O₂ therapy during exercise is an area of interest and active research. A summary of current evidence for benefits of supplemental O₂ therapy and a review of physiologic mechanisms underlying published observations are reviewed in this article.

Agreement between Cardiopulmonary Exercise Test and Modified 6-Min Walk Test in Determining Oxygen Uptake in COPD Patients with Different Severity Stages

BACKGROUND

In moderate-to-severe chronic obstructive pulmonary disease (COPD) patients the 6-min walk test (6MWT) is often exhaustive and correlates with the incremental cycle cardiopulmonary exercise test (CPET).

OBJECTIVES

The aim of this study was to assess the agreement between oxygen uptake (VO2) measured during the 6MWT by portable equipment and incremental cycle exercise in COPD patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) I-IV.

METHODS

A total of 30 patients with COPD GOLD I-IV (14 patients GOLD stage I and II and 16 patients GOLD stage III and IV) underwent a 6MWT and an incremental CPET. Breath-by-breath analysis for VO2, carbon dioxide output (VCO2), and minute ventilation (VE) were measured during each test. Blood gas analysis and lactate measurements were performed before, during, and after the test.

RESULTS

VO2 in COPD patients GOLD stage I and II was 16.2 ± 4.2 mL/kg/min measured by 6MWT and 20.5 ± 7.0 mL/kg/min measured by CPET as compared to GOLD stage III and IV (11.2 ± 3.7 mL/kg/min measured by 6MWT and 15.5 ± 4.3 mL/kg/min measured by CPET). No significant correlation in VO2 measurements could be found between both tests in COPD GOLD I and II (r = 0.17), whereas the VO2 significantly correlated in patients with COPD stage III and IV (r = 0.7).

CONCLUSIONS

A significant relationship between VO2 measured by 6MWT and CPET could only be found in patients with more severe COPD but not in milder stages. 6MWT and CPET provide different VO2 measurements in COPD patients. The two methods cannot be used interchangeably.

ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases

The objective of this document was to standardise published cardiopulmonary exercise testing (CPET) protocols for improved interpretation in clinical settings and multicentre research projects. This document: 1) summarises the protocols and procedures used in published studies focusing on incremental CPET in chronic lung conditions; 2) presents standard incremental protocols for CPET on a stationary cycle ergometer and a treadmill; and 3) provides patients' perspectives on CPET obtained through an online survey supported by the European Lung Foundation. We systematically reviewed published studies obtained from EMBASE, Medline, Scopus, Web of Science and the Cochrane Library from inception to January 2017. Of 7914 identified studies, 595 studies with 26 523 subjects were included. The literature supports a test protocol with a resting phase lasting at least 3 min, a 3-min unloaded phase, and an 8- to 12-min incremental phase with work rate increased linearly at least every minute, followed by a recovery phase of at least 2–3 min. Patients responding to the survey (n=295) perceived CPET as highly beneficial for their diagnostic assessment and informed the Task Force consensus. Future research should focus on the individualised estimation of optimal work rate increments across different lung diseases, and the collection of robust normative data.

The document facilitates standardisation of conducting, reporting and interpreting cardiopulmonary exercise tests in chronic lung diseases for comparison of reference data, multi-centre studies and assessment of interventional efficacy.http://bit.ly/31SXeB5

Cardiorespiratory fitness assessment and prediction of peak oxygen consumption by Incremental Shuttle Walking Test in healthy women

INTRODUCTION

Preliminary studies have showed that the Incremental Shuttle Walking Test (ISWT) is a maximal test, however comparison between ISWT with the cardiopulmonary exercise test (CEPT) has not yet performed in the healthy woman population. Furthermore, there is no regression equation available in the current literature to predict oxygen peak consumption (VO2 peak). Thus, this study aimed to compare the ISWT with CEPT and to develop an equation to predict peak oxygen uptake (VO2 peak) in healthy women participants.

METHODS

First, the VO2 peak, respiratory exchange ratio (R peak), heart rate max (HR max) and percentage of predicted HR max (% predicted HR max) were evaluated in the CEPT and ISWT (n = 40). Then, an equation was developed to predict the VO2 peak (n = 54) and its validation was performed (n = 20).

RESULTS

There were no significant differences between the ISWT and CEPT of VO2 peak, HR max and % predicted HR max values (P>0.05), except for R peak measure in the ISWT (1.22 ± 0.13) and CEPT (1.18 ± 0.1) (P = 0.022). Therefore, both tests showed a moderate positive correlation of VO2 peak (r = 0.51; P = 0.0007), HR max (r = 0.65; P<0.0001) and R peak (r = 0.55; P = 0.0002) and the Bland-Altman analysis showed agreement of VO2 peak (bias = -0.14). The distance walked on ISWT and age explained 36.3% (R2 Adjusted = 0.363) of the variance in VO2 peak. The equation developed was VO2 peak (predicted) = 19.793 + (0.02 x distance walked)-(0.236 x age). There was no statistically significant difference between the VO2 peak measured directly and the predicted, and the Bland-Altman analysis showed agreement (bias = 1.5 ml/kg/min).

CONCLUSION

ISWT is a maximal test showing similar results compared to the CEPT, and the predicted equation was valid and applicable for VO2 peak assessing in young adult healthy women.

Current challenges in managing comorbid heart failure and COPD

INTRODUCTION

Heart failure (HF) with reduced ejection fraction and chronic obstructive pulmonary disease (COPD) frequently coexist, particularly in the elderly. Given their rising prevalence and the contemporary trend to longer life expectancy, overlapping HF-COPD will become a major cause of morbidity and mortality in the next decade. Areas covered: Drawing on current clinical and physiological constructs, the consequences of negative cardiopulmonary interactions on the interpretation of pulmonary function and cardiopulmonary exercise tests in HF-COPD are discussed. Although those interactions may create challenges for the diagnosis and assessment of disease stability, they provide a valuable conceptual framework to rationalize HF-COPD treatment. The impact of COPD or HF on the pharmacological treatment of HF or COPD, respectively, is then comprehensively discussed. Authors finalize by outlining how the non-pharmacological treatment (i.e. rehabilitation and exercise reconditioning) can be tailored to the specific needs of patients with HF-COPD. Expert commentary: Randomized clinical trials testing the efficacy and safety of new medications for HF or COPD should include a sizeable fraction of patients with these coexistent pathologies. Multidisciplinary clinics involving cardiologists and respirologists trained in both diseases (with access to unified cardiorespiratory rehabilitation programs) are paramount to decrease the humanitarian and social burden of HF-COPD.

The 1-minute sit-to-stand test to detect exercise-induced oxygen desaturation in patients with interstitial lung disease

BACKGROUND

Although the 6-min walk test (6MWT) is the gold standard for assessing exercise-induced impairment of gas exchange, it cannot easily be performed in a clinical office environment. The aim of this study was to compare the 1-min sit-to-stand test (1STST) with the 6MWT for the ability to assess exercise-induced oxygen desaturation in patients with interstitial lung diseases (ILDs).

METHODS

A total of 107 patients were enrolled and classified into three groups: sarcoidosis, fibrotic idiopathic interstitial pneumonia (f-IIP), and other forms of ILD. The 6MWT and 1STST were performed on the same day, and pulmonary function tests, pulse oxygen saturation (SpO2), and dyspnea and fatigue (modified Borg scale) were assessed. SpO2 desaturation was evaluated by intraclass correlation coefficient (ICC), Bland-Altman analysis, and kappa (κ) coefficient in the whole population and the patient subgroups.

RESULTS

The SpO2 nadir during the 1STST and 6MWT showed good consistency [mean ± standard deviation: 92.5% ± 5% and 90% ± 7%, respectively; ICC 0.77, 95% confidence interval (CI) 0.71-0.83] and correlated strongly ( r = 0.9, p < 0.0001). The frequency of patients with oxygen desaturation ⩾4% was also consistent for the two exercise tests ( κ = 0.68, 95% CI 0.54-0.82). The number of repetitions in the 1STST correlated with the 6MWT distance ( r = 0.5, p < 0.0001), but the dyspnea scores were higher during the 1STST than the 6MWT ( p < 0.0001). These findings did not differ for the three patient subgroups.

CONCLUSION

The 1STST can measure exercise-induced desaturation in ILD patients and could be used as an alternative test to the 6MWT in office practice.

Prescribing Cycle Exercise Intensity Using Moderate Symptom Levels in Chronic Obstructive Pulmonary Disease

PURPOSE

Laboratory-based cardiopulmonary exercise testing from which to prescribe cycle training intensity in pulmonary rehabilitation for people with chronic obstructive pulmonary disease (COPD) is not readily available in clinical practice. Alternative methods of prescribing cycle exercise intensity, such as patient symptoms of dyspnea or rating of perceived exertion (RPE), have been used, but it is unknown whether cycle intensity based on such symptoms elicits an exercise intensity appropriate for achieving physiological training responses. The aim of the study was to determine the exercise intensity elicited when continuous cycle exercise was prescribed at symptoms of moderate dyspnea or RPE in people with COPD.

METHODS

Participants with diagnosed COPD performed lung function tests and an incremental cycle test to peak work capacity. On a subsequent day, participants performed 10 minutes of cycle exercise based on moderate symptoms (CycleSYMP) of either dyspnea or RPE, depending on which symptom limited the incremental cycle test. Oxygen uptake ((Equation is included in full-text article.)O2) was measured during all exercise using a portable metabolic system (Cosmed K4b).

RESULTS

Thirty participants, mean age of 70 ± 9 years and FEV1 60 ± 12% predicted, completed the study. The mean intensity achieved during CycleSYMP was 78 ± 12%(Equation is included in full-text article.)O2peak and 71 ± 18 % (Equation is included in full-text article.)O2Reserve. Steady-state (Equation is included in full-text article.)O2 was achieved by the sixth minute of CycleSYMP.

CONCLUSIONS

Using symptoms of moderate dyspnea or RPE as a method of prescribing cycle exercise elicited a high training intensity at which steady-state was achieved in people with mild to moderate COPD.

Physiological Responses of the Modified Shuttle Test in Adults With Cystic Fibrosis

PURPOSE

The modified shuttle test (MST) is increasingly used in clinical practice to assess functional capacity in patients with cystic fibrosis (CF). The purpose of this study was to evaluate the physiological responses of the MST in adults with CF as compared with the gold standard cardiopulmonary exercise test (CPET).

METHODS

Participants performed an MST and a CPET on a cycle ergometer in random order. Oxygen (O2) uptake ((Equation is included in full-text article.)O2), carbon dioxide (CO2) retention (end-tidal PCO2; PETCO2), minute ventilation, heart rate, and peripheral O2 saturation (SpO2) were continuously monitored. Whole blood lactate, dyspnea, and leg discomfort were recorded immediately after both exercises.

RESULTS

Twenty patients with CF (aged 33 ± 8 years; forced expiratory volume in 1 second = 48% ± 17%) completed both tests. Peak values for (Equation is included in full-text article.)O2 (27 ± 7 vs 24 ± 6 mL/kg/min), heart rate (169 ± 19 vs 163 ± 16 bpm), end PETCO2 (42 ± 7 vs 39 ± 8 mm Hg), and O2 desaturation (end SpO2, 86% ± 7% vs 90% ± 6%) were significantly higher during the MST than during the CPET (all Ps < .05). Leg discomfort and whole blood lactate were significantly higher after the CPET (both Ps < .05). Thirty-five percent and 40% of patients showed significant O2 desaturation and CO2 retention, respectively, during the MST, which was not detected during the CPET. A strong relationship was found between MST peak (Equation is included in full-text article.)O2 and body weight walking distance product (r = 0.90; P < .01).

CONCLUSIONS

The MST may provide a strong indicator of exercise tolerance in adults with CF as indicated by high peak (Equation is included in full-text article.)O2 values. In clinical practice, body weight walking distance should be considered as the primary outcome. This test is also better than cycle ergometry CPET for detecting O2 desaturation and CO2 retention, further emphasizing its clinical interest.

Assessment of dyspnea and dynamic hyperinflation in male patients with chronic obstructive pulmonary disease during a six minute walk test and an incremental treadmill cardiorespiratory exercise test

The six minute walk test (6MWT) is a standardized test that provides information on exercise capacity in patients with COPD. It is considered a submaximal test in opposition to incremental cardiopulmonary exercise tests (CPET) that provide valuable information on all the systems involved in exercise.

OBJECTIVES

1. To compare the perceptive, physiological responses and degree of dynamic hyperinflation during two exercise tests: the 6MWT and the incremental CPET on a treadmill. 2. To evaluate how dyspnea is related to dynamic hyperinflation (DH) and other functional parameters in both tests.

METHODS

29 stable COPD male patients, age 68±5.8 years, mean post-bronchodilator FEV1 57±11%, were recruited. To evaluate dynamic hyperinflation, inspiratory capacity (IC) was measured at rest and upon completing each one of the tests. At the same time, perceived dyspnea and leg discomfort were rated on specific modified Borg scales.

RESULTS

The mean walk distance in 6MWT was 494±88m. The Borg scale rating for shortness of breath upon completing the test was 4.7±2, whilst 2.9±2 for leg discomfort. IC changed from 2.53±0.63l before to 2.34±0.60l after completion of the test. In the treadmill CPET, maximal oxygen consumption (V˙O₂max) was 21.8±5mL/kg/min with 6.6±2 dyspnea and 4.3±2 leg discomfort on Borg scales. IC changed from 2.17±0.53l to 1.20±0.43l.

CONCLUSIONS

Dynamic hyperinflation occurs in male COPD patients during submaximal exercise such as the 6MWT. This phenomenon is more pronounced after incremental CPET on a treadmill. Despite being dyspnea the dominant limiting symptom for both tests, we observed different physiological responses.

Exertional dyspnoea in COPD: the clinical utility of cardiopulmonary exercise testing

Activity-related dyspnoea is often the most distressing symptom experienced by patients with chronic obstructive pulmonary disease (COPD) and can persist despite comprehensive medical management. It is now clear that dyspnoea during physical activity occurs across the spectrum of disease severity, even in those with mild airway obstruction. Our understanding of the nature and source of dyspnoea is incomplete, but current aetiological concepts emphasise the importance of increased central neural drive to breathe in the setting of a reduced ability of the respiratory system to appropriately respond. Since dyspnoea is provoked or aggravated by physical activity, its concurrent measurement during standardised laboratory exercise testing is clearly important. Combining measurement of perceptual and physiological responses during exercise can provide valuable insights into symptom severity and its pathophysiological underpinnings. This review summarises the abnormal physiological responses to exercise in COPD, as these form the basis for modern constructs of the neurobiology of exertional dyspnoea. The main objectives are: 1) to examine the role of cardiopulmonary exercise testing (CPET) in uncovering the physiological mechanisms of exertional dyspnoea in patients with mild-to-moderate COPD; 2) to examine the escalating negative sensory consequences of progressive respiratory impairment with disease advancement; and 3) to build a physiological rationale for individualised treatment optimisation based on CPET.

Physiological and clinical relevance of exercise ventilatory efficiency in COPD

Exercise ventilation (V'_E) relative to carbon dioxide output (V'_CO2 ) is particularly relevant to patients limited by the respiratory system, e.g. those with chronic obstructive pulmonary disease (COPD). High V'_E-V'_CO2 (poor ventilatory efficiency) has been found to be a key physiological abnormality in symptomatic patients with largely preserved forced expiratory volume in 1 s (FEV₁). Establishing an association between high V'_E-V'_CO2 and exertional dyspnoea in mild COPD provides evidence that exercise intolerance is not a mere consequence of detraining. As the disease evolves, poor ventilatory efficiency might help explaining "out-of-proportion" breathlessness (to FEV₁ impairment). Regardless, disease severity, cardiocirculatory co-morbidities such as heart failure and pulmonary hypertension have been found to increase V'_E-V'_CO2 In fact, a high V'_E-V'_CO2 has been found to be a powerful predictor of poor outcome in lung resection surgery. Moreover, a high V'_E-V'_CO2 has added value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of COPD severity. Documenting improved ventilatory efficiency after lung transplantation and lung volume reduction surgery provides objective evidence of treatment efficacy. Considering the usefulness of exercise ventilatory efficiency in different clinical scenarios, the V'_E-V'_CO2 relationship should be valued in the interpretation of cardiopulmonary exercise tests in patients with mild-to-end-stage COPD.

Ventilatory limitation and dynamic hyperinflation during exercise testing in Cystic Fibrosis

OBJECTIVE

To investigate the presence of dynamic hyperinflation after the Modified Shuttle Test (MST) and its relationship with lung function, exercise tolerance, and clinical symptoms in Cystic Fibrosis (CF).

METHODS

Retrospective observational study. Subjects in clinically stable condition with a CF diagnosis based on a positive sweat test (chloride >60 mEq/L) and/or presence of two disease causing mutations, with available data on MST, spirometry, maximal voluntary ventilation, and inspiratory capacity manoeuvres were considered for the analysis. Breathing reserve was calculated and a threshold value of 0.7 was subsequently chosen as a value of pulmonary mechanical limit. Subjects were then categorized into two groups according to the change in the inspiratory capacity from rest to peak exercise. Unconditional logistic regression was used to estimate unadjusted odds ratios, 95% confidence intervals and P-values.

RESULTS

Twenty-two subjects demonstrated evidence of dynamic hyperinflation during the MST. Thirteen out of 22 subjects were ventilatory limited during exercise including 5 of those without evidence of dynamic hyperinflation (P = 0.24). No combination of variables resulted in a parsimonious regression model.

CONCLUSIONS

Dynamic hyperinflation is common in CF and it is not associated with traditionally defined ventilatory limitation parameters during the MST. Pediatr Pulmonol. 2017;52:29-33. © 2016 Wiley Periodicals, Inc.

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.

Variability of gait speed during six minutes walking test in COPD and cystic fibrosis patients

BACKGROUND

Recently, gait speed reached an increasing importance in the management of respiratory patients. The aim of this retrospective study was to compare walking speed and physiological adaptations during the 6MWT in COPD and CF patients.

METHODS

6MWT performed by COPD and CF patients were retrospectively reviewed. Global and sequential walking speeds were measured on six minutes and every sequence of two minutes respectively. Heart rate, oxygen saturation and dyspnea were analyzed.

RESULTS

78 and 246 tests from CF and COPD patients were reviewed respectively. FEV1 (52.3 vs 56.2% pred) and FVC (72.5 vs 73.8% pred) were similar between both diseases. However, 6MWT in patients with CF were characterized by significantly higher heart rate, global walking speed and walking distance (+68%) while dyspnea evolutions and the proportions of patients presenting walking speed decline over the 6min were significantly lower.

CONCLUSION

Walking speed and cardio-respiratory parameters evolution during 6MWT differ between COPD and CF patients.

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.

Low bone mineral density in COPD patients with osteoporosis is related to low daily physical activity and high COPD assessment test scores

COPD patients have an increased prevalence of osteoporosis (OP) compared with healthy people. Physical inactivity in COPD patients is a crucial risk factor for OP; the COPD assessment test (CAT) is the newest assessment tool for the health status and daily activities of COPD patients. This study investigated the relationship among daily physical activity (DPA), CAT scores, and bone mineral density (BMD) in COPD patients with or without OP. This study included 30 participants. Ambulatory DPA was measured using actigraphy and oxygen saturation by using a pulse oximeter. BMD was measured using dual-energy X-ray absorptiometry. OP was defined as a T-score (standard deviations from a young, sex-specific reference mean BMD) less than or equal to −2.5 SD for the lumbar spine, total hip, and femoral neck. We quantified oxygen desaturation during DPA by using a desaturation index and recorded all DPA, except during sleep. COPD patients with OP had lower DPA and higher CAT scores than those of patients without OP. DPA was significantly positively correlated with (lumbar spine, total hip, and femoral neck) BMD (r=0.399, 0.602, 0.438, respectively, all P<0.05) and T-score (r=0.471, 0.531, 0.459, respectively, all P<0.05), whereas CAT scores were significantly negatively correlated with (total hip and femoral neck) BMD (r=−0.412, −0.552, respectively, P<0.05) and (lumbar spine, total hip, and femoral neck) T-score (r=−0.389, −0.429, −0.543, respectively, P<0.05). Low femoral neck BMD in COPD patients was related to high CAT scores. Our results show no significant difference in desaturation index, low SpO₂, and inflammatory markers (IL-6, TNF-α, IL-8/CXCL8, CRP, and 8-isoprostane) between the two groups. Chest physicians should be aware that COPD patients with OP have low DPA and high CAT scores.

Prescription of walking exercise intensity from the 6-minute walk test in people with chronic obstructive pulmonary disease

PURPOSE

The 6-minute walk test (6MWT) is widely used in clinical practice, particularly to assess functional exercise capacity and to prescribe walking training intensity in people with chronic obstructive pulmonary disease (COPD). However, the actual walking intensity prescribed from the 6MWT, in terms of percent peak oxygen uptake (%(Equation is included in full-text article.)O2peak) and percent (Equation is included in full-text article.)O2 reserve (%(Equation is included in full-text article.)O2R), has not been previously reported. This study aims to examine the exercise intensity when walking training is prescribed at 80% average 6MWT speed.

METHODS

Patients with COPD (N = 45) were recruited. Peak (Equation is included in full-text article.)O2 from an incremental cycle test and 6MWT and (Equation is included in full-text article.)O2 from a 10-minute walking exercise (Walk-10) were measured by a portable metabolic system (Cosmed K4b; Cosmed, Rome, Italy). Walk-10 was done on the same oval course as the 6MWT. Participants were asked to walk at 80% average 6MWT speed for 10 minutes continuously.

RESULTS

Four participants could not complete Walk-10 and 2 did not perform Walk-10 due to low 6MWT distance. The remaining 39 participants with mean (SD) forced expiratory volume in 1 minute of 58 (19)% predicted completed Walk-10. The mean intensity of Walk-10 was 69 (17)% (Equation is included in full-text article.)O2R or 77 (13)% (Equation is included in full-text article.)O2peak. Steady-state (Equation is included in full-text article.)O2 was achieved within the first 4 minutes of Walk-10.

CONCLUSION

Walking exercise prescribed at 80% average 6MWT speed resulted in a high but tolerable exercise intensity that is likely to result in training benefits in most people with COPD.

Dynamic hyperinflation and dyspnea during the 6-minute walk test in stable chronic obstructive pulmonary disease patients

The purpose of this study was to investigate the relationship between dynamic hyperinflation and dyspnea and to clarify the characteristics of dyspnea during the 6-minute walk test (6MWT) in chronic obstructive pulmonary disease patients. Twenty-three subjects with stable moderate chronic obstructive pulmonary disease (age 73.8±5.8 years, all male) took part in this study. During the 6MWT, ventilatory and gas exchange parameters were measured using a portable respiratory gas analysis system. Dyspnea and oxygen saturation were recorded at the end of every 2 minute period during the test. There was a significant decrease in inspiratory capacity during the 6MWT. This suggested that dynamic hyperinflation had occurred. Dyspnea showed a significant linear increase, and there was a significant negative correlation with inspiratory capacity. It was suggested that one of the reasons that dyspnea developed during the 6MWT was the dynamic hyperinflation. Even though the tidal volume increased little after 2 minutes, dyspnea increased linearly to the end of the 6MWT. These results suggest that the mechanisms generating dyspnea during the 6MWT were the sense of respiratory effort at an early stage and then the mismatch between central motor command output and respiratory system movement.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

Exercise ventilatory inefficiency in mild to end-stage COPD

Ventilatory inefficiency during exercise is a key pathophysiological feature of chronic obstructive pulmonary disease. Currently, it is unknown how this physiological marker relates to clinically relevant outcomes as resting ventilatory impairment progresses across disease stages.

Slope and intercept of the linear region of the ventilation–carbon dioxide output relationship and the ratio between these variables, at the lowest point (nadir), were contrasted in 316 patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1–4 (forced expiratory volume in 1 s, ranging from 148% pred to 12% pred) and 69 aged- and gender-matched controls,

Compared to controls, slope and intercept were higher in GOLD stages 1 and 2, leading to higher nadirs (p<0.05). Despite even larger intercepts in GOLD stages 3 and 4, slopes diminished as disease evolved (from mean±sd35±6 in GOLD stage 1 to 24±5 in GOLD stage 3, p<0.05). As a result, there were no significant differences in nadirs among patient groups. Higher intercepts, across all stages (p<0.01), and to a lesser extent lower slopes in GOLD stages 2–4 (p<0.05), were related to greater mechanical constraints, worsening pulmonary gas exchange, higher dyspnoea scores, and poorer exercise capacity.

Increases in the ventilation intercept best indicate the progression of exercise ventilatory inefficiency across the whole spectrum of chronic obstructive pulmonary disease severity.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Cardiac, ventilatory, and metabolic adjustments in chronic obstructive pulmonary disease patients during the performance of Glittre activities of daily living test

Functional status and quality of life are measures of the chronic obstructive pulmonary disease (COPD) patient’s health status and can demonstrate the impact of the disease on the patient’s ability to perform activities of daily living (ADLs). The Glittre-ADL test was developed to evaluate the functional status of COPD patients and their ability to perform activities of daily life.

The objective of this study was to evaluate the cardiac, respiratory, and metabolic adjustments and reproducibility of the Glittre ADL test performed by COPD patients.

Twenty-two mild to severe COPD patients (forced expiratory volume in 1 second (FEV1): 56.6 ± 19.9% predicted; mean age: 66.3 ± 9.18 years old) were enrolled in this study. Metabolic (oxygen uptake (VO2), carbon dioxide production (VCO2), pulmonary ventilation (VE)/VCO2, and VE/VO2), ventilatory (tidal volume, respiratory rate, and VE), and cardiovascular (pulse oxygen saturation, VO2/heart rate (HR), and HR) variables, lower limbs fatigue, and dyspnea (Borg score) after each lap of two Glittre ADL test were analyzed.

All metabolic, ventilatory, and cardiac variables increased their values up to the third lap and remained stable (plateau) until the end of the test (five laps; multivariate analysis); there was no difference among the time spent to complete each of the five laps in each test and between tests (total time of second test: 4 minutes and 3 seconds); the second test was 17.8 seconds (6.6%) shorter than the first one (NS). All variables were highly reproducible in the two tests (NS). At the end of the test, patients reached 87.7% of the VO2 max, 81% of VE peak, and 88.5% of the HR peak obtained from an incremental maximal test on a treadmill.

The Glittre ADL test is easy for COPD patients to perform and is a highly reproducible test in COPD patients with mild to severe stages of the disease. In addition, our results suggest that it is possible to demonstrate the patient’s functional capacity with a single test of only three laps, making it faster and easier to apply and less stressful for some patients.

Alternatives to the six-minute walk test in pulmonary arterial hypertension

INTRODUCTION

The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH. We tested the hypothesis that endurance tests induce a near-maximal physiological demand comparable to incremental tests. We also hypothesized that differences in respiratory response during exercise would be related to the characteristics of the exercise tests.

METHODS

Within two weeks, twenty-one PAH patients (mean age: 54(15) years; mean pulmonary arterial pressure: 42(12) mmHg) completed two cycling exercise tests (incremental cardiopulmonary cycling exercise test (CPET) and CET) and three field tests (ISWT, ESWT and six-minute walk test (6MWT)). Physiological parameters were continuously monitored using the same portable telemetric device.

RESULTS

Peak oxygen consumption (VO(2peak)) was similar amongst the five exercise tests (p = 0.90 by ANOVA). Walking distance correlated markedly with the VO(2peak) reached during field tests, especially when weight was taken into account. At 100% exercise, most physiological parameters were similar between incremental and endurance tests. However, the trends overtime differed. In the incremental tests, slopes for these parameters rose steadily over the entire duration of the tests, whereas in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise at which point they appeared far less steep until test end. Moreover, cycling exercise tests induced higher respiratory exchange ratio, ventilatory demand and enhanced leg fatigue measured subjectively and objectively.

CONCLUSION

Endurance tests induce a maximal physiological demand in PAH. Differences in peak respiratory response during exercise are related to the modality (cycling vs. walking) rather than the progression (endurance vs. incremental) of the exercise tests.

Activity restriction in mild COPD: a challenging clinical problem

Dyspnea, exercise intolerance, and activity restriction are already apparent in mild chronic obstructive pulmonary disease (COPD). However, patients may not seek medical help until their symptoms become troublesome and persistent and significant respiratory impairment is already present; as a consequence, further sustained physical inactivity may contribute to disease progression. Ventilatory and gas exchange impairment, cardiac dysfunction, and skeletal muscle dysfunction are present to a variable degree in patients with mild COPD, and collectively may contribute to exercise intolerance. As such, there is increasing interest in evaluating exercise tolerance and physical activity in symptomatic patients with COPD who have mild airway obstruction, as defined by spirometry. Simple questionnaires, eg, the modified British Medical Research Council dyspnea scale and the COPD Assessment Test, or exercise tests, eg, the 6-minute or incremental and endurance exercise tests can be used to assess exercise performance and functional status. Pedometers and accelerometers are used to evaluate physical activity, and endurance tests (cycle or treadmill) using constant work rate protocols are used to assess the effects of interventions such as pulmonary rehabilitation. In addition, alternative outcome measurements, such as tests of small airway dysfunction and laboratory-based exercise tests, are used to measure the extent of physiological impairment in individuals with persistent dyspnea. This review describes the mechanisms of exercise limitation in patients with mild COPD and the interventions that can potentially improve exercise tolerance. Also discussed are the benefits of pulmonary rehabilitation and the potential role of pharmacologic treatment in symptomatic patients with mild COPD.

Characteristics and determinants of endurance cycle ergometry and six-minute walk distance in patients with COPD

Background

Exercise tolerance can be assessed by the cycle endurance test (CET) and six-minute walk test (6MWT) in patients with Chronic Obstructive Pulmonary Disease (COPD). We sought to investigate the characteristics of functional exercise performance and determinants of the CET and 6MWT in a large clinical cohort of COPD patients.

Methods

A dataset of 2053 COPD patients (43% female, age: 66.9 ± 9.5 years, FEV₁% predicted: 48.2 ± 23.2) was analyzed retrospectively. Patients underwent, amongst others, respiratory function evaluation; medical tests and questionnaires, one maximal incremental cycle test where peak work rate was determined and two functional exercise tests: a CET at 75% of peak work rate and 6MWT. A stepwise multiple linear regression was used to assess determinants.

Results

On average, patients had impaired exercise tolerance (peak work rate: 56 ± 27% predicted, 6MWT: 69 ± 17% predicted). A total of 2002 patients had CET time of duration (CET-T_end) less than 20 min while only 51 (2.5%) of the patients achieved 20 min of CET-T_end . In former patients, the percent of predicted peak work rate achieved differed significantly between men (48 ± 21% predicted) and women (67 ± 31% predicted). In contrast, CET-T_end was longer in men (286 ± 174 s vs 250 ± 153 s, p < 0.001). Also, six minute walking distance (6MWD) was higher in men compared to women, both in absolute terms as in percent of predicted (443 m, 67%predicted vs 431 m, 72%predicted, p < 0.05). Gender was associated with the CET-T_end but BMI, FEV₁ and FRC were related to the 6MWD highlighting the different determinants of exercise performance between CET and 6MWT.

Conclusions

CET-T_end is a valuable outcome of CET as it is related to multiple clinical aspects of disease severity in COPD. Gender difference should temper the interpretation of CET.

The continuum of physiological impairment during treadmill walking in patients with mild-to-moderate COPD: patient characterization phase of a randomized clinical trial

BACKGROUND

To have a better understanding of the mechanisms of exercise limitation in mild-to-moderate chronic obstructive pulmonary disease (COPD), we compared detailed respiratory physiology in patients with COPD and healthy age- and sex-matched controls.

METHODS

Data were collected during the pre-treatment, patient characterization phase of a multicenter, randomized, double-blind, crossover study. Patients with COPD met Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 or 2 spirometric criteria, were symptomatic, and had evidence of gas trapping during exercise. All participants completed pulmonary function and symptom-limited incremental treadmill exercise tests.

RESULTS

Chronic activity-related dyspnea measured by Baseline Dyspnea Index was similarly increased in patients with GOLD 1 (n = 41) and 2 (n = 63) COPD compared with controls (n = 104). Plethysmographic lung volumes were increased and lung diffusing capacity was decreased in both GOLD groups. Peak oxygen uptake and work rate were reduced in both GOLD groups compared with controls (p<0.001). Submaximal ventilation, dyspnea, and leg discomfort ratings were higher for a given work rate in both GOLD groups compared with controls. Resting inspiratory capacity, peak ventilation, and tidal volume were reduced in patients with GOLD 2 COPD compared with patients with GOLD 1 COPD and controls (p<0.001).

CONCLUSIONS

Lower exercise tolerance in patients with GOLD 1 and 2 COPD compared with controls was explained by greater mechanical abnormalities, greater ventilatory requirements, and increased subjective discomfort. Lower resting inspiratory capacity in patients with GOLD 2 COPD was associated with greater mechanical constraints and lower peak ventilation compared with patients with GOLD 1 COPD and controls.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01072396.

Exercise training modalities and strategies to improve exercise performance in patients with respiratory disease

Pulmonary rehabilitation is an evidence-based, multidisciplinary, comprehensive intervention for patients with chronic respiratory diseases who are symptomatic and whose daily living activities are often restricted. Pulmonary rehabilitation programs are designed to improve the physical and emotional condition of people with chronic respiratory disease and to promote long-term adherence to health-enhancing behavior. Exercise training is at the core of pulmonary rehabilitation (PR) programs. The benefits of exercise training include decreased dyspnea, improved health-related quality of life, fewer days of hospitalization, and decreased health-care utilization. To gain PR benefits, patients should be able to complete an exercise training program, preferably with high intensity exercise, and it is likely that these benefits will translate into a change from a pattern of a sedentary lifestyle to a physically active lifestyle. Chronic respiratory patients, namely COPD patients, have a low exercise tolerance due to multiple factors, such as dynamic hyperinflation and peripheral muscle dysfunction. In this article, the authors describe a variety of modalities and strategies to overcome exercise limitations and improve the effects of exercise training.

[Is stairclimbing a maximal exercise test for COPD patients?]

INTRODUCTION

Variable tests evaluate the cardio-respiratory working capacity of COPD patients. Stairclimbing testing has been less studied. Our hypothesis is that this functional exercise test represents a submaximal effort for these patients.

METHOD

We compared in 10 COPD patients the main metabolic and ventilatory parameters at the end of an effort between stairclimbing and cycle ergometer test.

RESULTS

The following parameters studied (RER, V'CO2, lactates, V'E) are significantly lower for stair climbing. Nevertheless, in 8 patients, the V'O2 at the end of the stairclimbing testing is equal to the cycle ergometer test and in two patients superior. Concerning the evolution of some parameters during stairclimbing, 2 distinct profiles were observed: stabilization of the V'O2, HR, V'E and Vt (6/10 patients) or a constant increase of those parameters (4/10 patients).

CONCLUSION

Stairclimbing represents a submaximal effort for the majority of COPD patients combined with a high metabolic cost. However, some COPD patients execute a maximal effort like in the cycle ergometer test when climbing stairs. These two groups could not be differentiated with the rest lung function data. The hypothesis of different mechanical constraints and/or motivation is suggested.

A 6MWT index to predict O2 flow correcting exercise induced SpO2 desaturation in ILD

INTRODUCTION

Ambulatory oxygen (O2) is prescribed to interstitial lung disease (ILD) patients with mild hypoxemia, breathlessness and dyspnea on exertion. Oxygen titration is generally done with the 6 minute walk test (6MWT) to determine the O2 flow preventing oxygen saturation by pulse oximetry (SpO2) from falling below 88%. His study was designed to generate a 6MWT index predicting the O2 flow allowing completion of the 6MWT without oxygen desaturation.

METHODS

Oxygen titration data from a group of 66 ILD patients and 30 controls, were used to generate the algorithm determining an index (O2-GAP) predicting oxygen flow required to complete a 6MWT without desaturation below 88%. This index was validated in a group of 93 ILD patients.

RESULTS

The O2-GAP index, as obtained from the derivation population, (r(2) = 0.97, p < 0.001) was shown to correctly predict the oxygen flow required to complete the 6MWT without SpO2 falling below 88% validated in the validation population (r(2) = 0.842; p < 0.001).

CONCLUSIONS

The O2-GAP index appears to be a useful tool to titrate ambulatory O2 with a single 6MWT on room air in ILD patients with breathlessness and dyspnea on exertion.

Xbox Kinect™ represents high intensity exercise for adults with cystic fibrosis

BACKGROUND

Exercise is important for patients with cystic fibrosis (CF). Interactive gaming consoles are a new trend in exercise. This study sought to determine the exercise intensity of training using the Xbox Kinect(™).

METHODS

Participants with CF completed two sessions separated by ≤10 days. The first session involved a cardiopulmonary exercise test (CPET) to measure peak exercise capacity. The second session involved 20 min of exercise using the Xbox Kinect™.

RESULTS

Ten participants (median [interquartile range] FEV1 58 [46]%, 29 [6] years, 6 males) completed the study. The average heart rate over the final 10 min of exercise using the Xbox Kinect™, expressed as a percentage of the peak heart rate achieved on the CPET, was 86% (95% confidence interval, 81 to 92%).

CONCLUSIONS

Training using the Xbox Kinect™ represents high intensity exercise for adults with CF and may be a suitable alternative to conventional exercise modalities.