Exercise & Sports Science Australia (ESSA) position statement on exercise and chronic obstructive pulmonary disease

Effectiveness of high-intensity interval training in rehabilitation nursing for mild-to-moderate stable COPD patients: a randomized controlled clinical trial

OBJECTIVE

The current study was conducted to explore the clinical impact of high-intensity interval training (HIIT) in rehabilitation nursing on improving cardiopulmonary function and exercise capacity in COPD patients.

METHODS

A total of thirty-one COPD patients underwent HIIT, while an equal number underwent moderate-intensity continuous training (MICT) were included in this randomized controlled clinical study. The randomization method used was stratified block randomization, stratified by center. During the 6 months follow-up period, the clinical data, including cardiopulmonary exercise testing (CPET) results, cardiopulmonary function index, quality of life, and follow-up outcomes, were collected before and after the interventions. The therapeutic effects of the two groups were compared.

RESULTS

After the intervention, the HIIT group exhibited significantly higher peak power, exercise test duration, anaerobic threshold, peak oxygen uptake, peak ventilation, FEV1/FVC ratio, FEV1% of expected value, LVEF (%), and SF-36 scores compared to the MICT group (P < 0.05). Moreover, LVEDD was significantly lower in the HIIT group compared to the MICT group (P < 0.05). At the 6-month follow-up, the incidence of COPD acute exacerbation in the HIIT group was significantly lower than in the MICT group (P < 0.05).

CONCLUSION

Implementation of HIIT in rehabilitation nursing effectively improved cardiopulmonary function and exercise capacity in COPD patients during clinical treatment, highlighting its promising application potential.

TRIAL REGISTRATION

This study was previously registered at Chinese Clinical Trial Registry (Date 11/05/2022 Number ChiCTR2200059764).

Optimal intensity and type of lower limb aerobic training for patients with chronic obstructive pulmonary disease: a systematic review and network meta-analysis of RCTs

BACKGROUND

Lower limb aerobic exercise is the core component of pulmonary rehabilitation for chronic obstructive pulmonary disease (COPD) patients. The optimal intensity and type (e.g., interval or continuous) of exercise training remains to be determined.

OBJECTIVES

We aimed to evaluate the optimal intensities and types of lower limb aerobic exercise in patients with COPD.

DESIGN

Systematic review and network meta-analysis of randomized controlled trials.

DATA SOURCES AND METHODS

The PubMed, Web of Science, Embase, and the Cochrane Central Register of Controlled Trials were searched for relevant data. The interventions were classified according to their intensity and type as high-intensity interval training (HIIT), high-intensity continuous training (HICT), moderate-intensity continuous training (MICT), and low-intensity continuous training (LICT). We assessed exercise capacity using peak work rate (Wpeak) and the 6-min walking test (6-MWT). Lung function was evaluated by measuring peak minute ventilation (VE) and the percentage of predicted FEV1 (FEV1pred%). Dyspnea was assessed using the Modified Medical Research Council (mMRC) scale. Quality of life was measured with the Chronic Respiratory Questionnaire (CRQ).

RESULTS

Fifteen studies were identified (979 subjects). HIIT showed the greatest improvement in Wpeak, 6-MWT, VE, and mMRC compared to usual care (MD 18.48 (95% CI 12.35, 24.60), 67.73 (34.89, 100.57), 6.26 (2.81, 9.72), and -0.53 (-0.89, -0.17), respectively) and showed the improvement in CRQ (MD 10.80 (95% CI 1.65, 19.95)). MICT showed improvement in Wpeak and 6-MWT (MD 18.28 (95% CI 11.20, 25.22), 61.92 (28.34, 95.51)) similar to HICT (MD 16.08 (95% CI 8.19, 23.84), 64.64 (28.70, 100.57)) and showed the highest improvement in CRQ compared to usual care (MD 10.83 (95% CI 1.68, 19.98)). LICT significantly improved Wpeak compared to usual care (MD 13.47 (95% CI 4.77, 22.13)). The quality of evidence for outcomes varied from very low to moderate.

CONCLUSION

HIIT and MICT might be optimal training approaches for patients with COPD. LICT exhibited limited clinical efficacy. While HICT was as effective as MICT, it caused more dyspnea.

TRIAL REGISTRATION

This systematic review and network meta-analysis was prospectively registered with PROSPERO (No. CRD 42024520134).

Effect of adding neuromuscular electrical stimulation for patients with moderate to severe chronic obstructive pulmonary disease: Systematic review and meta-analysis

BACKGROUND

Healthcare providers have faced challenges for patients with moderate and severe chronic obstructive pulmonary disease (COPD) in conducting their pulmonary rehabilitation due to dyspnea and exercise intolerance. Neuromuscular electrical stimulation (NMES) has been used to improve the muscle group's power and endurance without adding pulmonary workload, which might be used as a potential adjuvant rehabilitation method and thus to improve patients' pulmonary functions.

METHODS

This was a systematic review and meta-analysis of randomized controlled trials. Data were retrieved from PubMed, CINAHL, Academic Search Complete, Cochrane Library, and Airiti Library databases from the inception of the database to December 2022. The Cochrane Collaboration tool was used to assess the risk of bias. Two reviewers independently assessed, extracted, and appraised the included studies. Then, the grading of recommendations, assessment, development, and evaluation (GRADE) methodology was used for assessing the certainty of evidence. The pooled estimates were calculated using a random-effects model.

RESULTS

In total, 19 studies involving 589 moderate to severe COPD patients were analyzed. Compared with controls, adding NMES to pulmonary rehabilitation could significantly increase exercise capacity, physical activity function, and health-related quality of life (HRQoL) (all p < 0.05). The GRADE results showed low to very low certainty of evidence levels.

CONCLUSION

NMES could improve exercise capacity and reduce the perceived sensation of dyspnea during exercise and is recommended as an effective adjuvant training modality in the rehabilitation for moderate to severe COPD patients.

Aerobic exercise training engages the canonical wnt pathway to improve pulmonary function and inflammation in COPD

BACKGROUND

We studied whether the exercise improves cigarette smoke (CS) induced chronic obstructive pulmonary disease (COPD) in mice through inhibition of inflammation mediated by Wnt/β-catenin-peroxisome proliferator-activated receptor (PPAR) γ signaling.

METHODS

Firstly, we observed the effect of exercise on pulmonary inflammation, lung function, and Wnt/β-catenin-PPARγ. A total of 30 male C57BL/6J mice were divided into the control group (CG), smoke group (SG), low-intensity exercise group (LEG), moderate-intensity exercise group (MEG), and high-intensity exercise group (HEG). All the groups, except for CG, underwent whole-body progressive exposure to CS for 25 weeks. Then, we assessed the maximal exercise capacity of mice from the LEG, MEG, and HEG, and performed an 8-week treadmill exercise intervention. Then, we used LiCl (Wnt/β-catenin agonist) and XAV939 (Wnt/β-catenin antagonist) to investigate whether Wnt/β-catenin-PPARγ pathway played a role in the improvement of COPD via exercise. Male C57BL/6J mice were randomly divided into six groups (n = 6 per group): CG, SG, LiCl group, LiCl and exercise group, XAV939 group, and XAV939 and exercise group. Mice except those in the CG were exposed to CS, and those in the exercise groups were subjected to moderate-intensity exercise training. All the mice were subjected to lung function test, lung histological assessment, and analysis of inflammatory markers in the bronchoalveolar lavage fluid, as well as detection of Wnt1, β-catenin and PPARγ proteins in the lung tissue.

RESULTS

Exercise of various intensities alleviated lung structural changes, pulmonary function and inflammation in COPD, with moderate-intensity exercise exhibiting significant and comprehensive effects on the alleviation of pulmonary inflammation and improvement of lung function. Low-, moderate-, and high-intensity exercise decreased β-catenin levels and increased those of PPARγ significantly, and only moderate-intensity exercise reduced the level of Wnt1 protein. Moderate-intensity exercise relieved the inflammation aggravated by Wnt agonist. Wnt antagonist combined with moderate-intensity exercise increased the levels of PPARγ, which may explain the highest improvement of pulmonary function observed in this group.

CONCLUSIONS

Exercise effectively decreases COPD pulmonary inflammation and improves pulmonary function. The beneficial role of exercise may be exerted through Wnt/β-catenin-PPARγ pathway.

Resistance Exercise Minimal Dose Strategies for Increasing Muscle Strength in the General Population: an Overview

Many individuals do not participate in resistance exercise, with perceived lack of time being a key barrier. Minimal dose strategies, which generally reduce weekly exercise volumes to less than recommended guidelines, might improve muscle strength with minimal time investment. However, minimal dose strategies and their effects on muscle strength are still unclear. Here our aims are to define and characterize minimal dose resistance exercise strategies and summarize their effects on muscle strength in individuals who are not currently engaged in resistance exercise. The minimal dose strategies overviewed were: "Weekend Warrior," single-set resistance exercise, resistance exercise "snacking," practicing the strength test, and eccentric minimal doses. "Weekend Warrior," which minimizes training frequency, is resistance exercise performed in one weekly session. Single-set resistance exercise, which minimizes set number and session duration, is one set of multiple exercises performed multiple times per week. "Snacks," which minimize exercise number and session duration, are brief bouts (few minutes) of resistance exercise performed once or more daily. Practicing the strength test, which minimizes repetition number and session duration, is one maximal repetition performed in one or more sets, multiple days per week. Eccentric minimal doses, which eliminate or minimize concentric phase muscle actions, are low weekly volumes of submaximal or maximal eccentric-only repetitions. All approaches increase muscle strength, and some approaches improve other outcomes of health and fitness. "Weekend Warrior" and single-set resistance exercise are the approaches most strongly supported by current research, while snacking and eccentric minimal doses are emerging concepts with promising results. Public health programs can promote small volumes of resistance exercise as being better for muscle strength than no resistance exercise at all.

In adults with advanced lung disease, the 1-minute sit-to-stand test underestimates exertional desaturation compared with the 6-minute walk test: an observational study

QUESTION

In adults with advanced lung disease, do the 6-minute walk test (6MWT) and 1-minute sit-to-stand test (1minSTS) elicit similar cardiorespiratory responses? Can the 6-minute walk distance (6MWD) be estimated from the 1minSTS result?

DESIGN

Prospective observational study using data collected during routine clinical practice.

PARTICIPANTS

Eighty adults (43 males) with advanced lung disease, a mean age of 64 years (SD 10) and a mean forced expiratory volume in 1 second of 1.65 L (SD 0.77).

OUTCOME MEASURES

Participants completed a 6MWT and a 1minSTS. During both tests, oxygen saturation (SpO2), pulse rate, dyspnoea and leg fatigue (Borg 0 to 10) were recorded.

RESULTS

Compared with the 6MWT, the 1minSTS resulted in higher nadir SpO2 (MD 4%, 95% CI 3 to 5), lower end-test pulse rate (MD -4 beats/minute, 95% CI -6 to -1), similar dyspnoea (MD -0.3, 95% CI -0.6 to 0.1) and greater leg fatigue (MD 1.1, 95% CI 0.6 to 1.6). Among the participants who demonstrated severe desaturation (SpO2 nadir < 85%) on the 6MWT (n = 18), five and ten participants were classified as moderate (nadir 85 to 89%) or mild desaturators (nadir ≥ 90%), respectively, on the 1minSTS. The relationship between the 6MWD and 1minSTS was: 6MWD (m) = 247 + (7 × number of transitions achieved during the 1minSTS) with poor predictive ability (r2 = 0.44).

CONCLUSION

The 1minSTS elicited less desaturation than the 6MWT and classified a smaller proportion of people as 'severe desaturators' on exertion. It is therefore inappropriate to use the nadir SpO2 recorded during a 1minSTS to make decisions about whether strategies are needed to prevent severe transient exertional desaturation during walking-based exercise. Further, the extent to which performance on the 1minSTS can estimate a person's 6MWD is poor. For these reasons, the 1minSTS is unlikely to be helpful when prescribing walking-based exercise.

High-intensity interval training improves the outcomes of patients with chronic obstructive pulmonary disease: A meta-analysis of randomized controlled trials

BACKGROUND

Pulmonary exercise is an important part in the treatment of chronic obstructive pulmonary disease (COPD). We aimed to evaluate the effects and safety of high-intensity interval training (HIIT) in patients with COPD, to provide insights to the COPD treatment and care.

METHODS

Two investigators searched PubMed, Medline, Embase, web of Science, Cochrane library, China National Knowledge Infrastructure (CNKI), Wanfang, and Weipu databases up to Sept 15, 2022 for randomized controlled trials (RCTs) on the effects and safety of HIIT for COPD patients. RevMan5.3 software was used for statistical analysis.

RESULTS

A total of 20 RCTs involving 962 COPD patients were finally included. 514 patients underwent HIIT interventions. Meta-analysis showed that HIIT increased the peak oxygen consumption (SMD = 0.30, 95%CI:0.14-0.46), peak minute ventilation (SMD = 0.26, 95%CI: 0.05-0.47), peak work rate (SMD = 0.34, 95%CI: 0.17-0.51), 6-min walking distance (SMD = 0.39, 95%CI: 0.23-0.55) in COPD patients (all P < 0.05). HIIT improved the quality of life (SMD = 0.30, 95%CI: 0.06-0.54) and reduced the dyspnea (SMD = -0.27, 95%CI: -0.51∼-0.03) in COPD patients (all P < 0.05). There were no significant differences in the forced expiratory volume in 1 s/forced vital capacity (SMD = 0.28, 95%CI: -0.01-0.56) and St. George's Respiratory Questionnaire score (SMD = -0.35, 95%CI: -0.73-0.03) between HIIT and control group (all P > 0.05). There was no publication bias analyzed by the Egger test and funnel plots (all P > 0.05).

CONCLUSIONS

HIIT may be beneficial to improve the pulmonary function, exercise capacity and quality of life of patients with COPD, which is worthy of clinical promotion for COPD treatment and care.

Clinical Impacts of Interventions for Physical Activity and Sedentary Behavior on Patients with Chronic Obstructive Pulmonary Disease

Recently, physical activity has increasingly become the focus in patients with chronic obstructive airway disease (COPD) because it is a strong predictor of COPD-related mortality. In addition, sedentary behavior, which is included as a category of physical inactivity including such behaviors as sitting or lying down, has an independent clinical impact on COPD patients. The present review examines clinical data related to physical activity, focusing on the definition, associated factors, beneficial effects, and biological mechanisms in patients with COPD and with respect to human health regardless of COPD. The data related to how sedentary behavior is associated with human health and COPD outcomes are also examined. Lastly, possible interventions to improve physical activity or sedentary behavior, such as bronchodilators and pulmonary rehabilitation with behavior modification, to ameliorate the pathophysiology of COPD patients are described. A better understanding of the clinical impact of physical activity or sedentary behavior may lead to the planning of a future intervention study to establish high-level evidence.

Dissociation between physical capacity and daily physical activity in COPD patients. A population-based approach

BADKGROUND

Physical capacity (PC) and daily physical activity (PA) are two crucial factors in the clinical course of COPD, although they do not always maintain a close relationship. The objectives were to evaluate the frequency of PC-PA dissociation in patients with COPD and subjects without airflow limitation (AL) and to identify its risk factors.

METHODS

A sample of 319 COPD patients and 399 subjects without AL was consecutively obtained from a population-based sample of 9092 subjects evaluated in the EPISCAN II study. Baseline evaluation included clinical questionnaires, lung function testing, blood analysis and low-dose computed tomography (CT) scan with evaluation of lung density and airway wall thickness. A distance walked in 6 min > 70% predicted was considered an indicator of normal PC, while a Yale Physical Activity Survey summary index score <51 was used to identify with sedentary lifestyle.

RESULTS

166 COPD patients (52.0%) reported a sedentary lifestyle with evidence of preserved PC, while this phenomenon was present in 188 (47.1%) subjects without AL. In the COPD group, symptoms of chronic bronchitis, depression and elevated hematocrit and blood eosinophil count were identified as independent risk factors for PC-PA dissociation. In turn, in the subjects without AL, the risk factors for PC-PA dissociation were low fat-free mass, obesity and anxiety, as well as reduced levels of HDL-cholesterol and the absence of osteoporosis.

CONCLUSIONS

Almost half of COPD patients and subjects without airflow limitation with preserved PC maintain a sedentary lifestyle, with different risk factors for sedentarism between both groups.

Effects of exercise-based home pulmonary rehabilitation on patients with chronic obstructive pulmonary disease: An overview of systematic review

BACKGROUND

Clinical research on exercise-based home pulmonary rehabilitation (HPR) effectiveness in chronic obstructive pulmonary disease (COPD) treatment is rising, as are associated systematic reviews/meta-analyses (SRs/MAs). However, different SRs/MAs vary in outcome indicators, analysis methodologies, literature quality, and findings. This overview aimed to describe the findings of these SRs/MAs and assess their methodological quality.

METHODS

From inception until April 2022, we searched PubMed, Web of Science, Cochrane Library, EMBASE, China National Knowledge Infrastructure (CNKI), and Wan Fang. Two researchers searched these SRs/MAs separately, collected the data, and cross-checked it using predetermined rules. The Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR 2) was used to evaluate the methodological quality of each contained SR/MA. The evidence was assessed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2009 (PRISMA-2009). The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to determine the validity of the results.

RESULTS

A total of 433 records were found, with 44 chosen for full-text review. There were 11 SRs/MAs that matched the inclusion criteria. Our overview included studies published from 2010 to 2022. According to the AMSTAR 2 tool, one had low methodological quality, while the other 10 SRs/MAs had very low quality. The PRISMA statement revealed a low rate of complete reporting for eight items. The GRADE tool, on the other hand, revealed that the evidence quality for most outcomes was very low to moderate.

CONCLUSION

According to current research, exercise-based HPR may benefit COPD patients. Nevertheless, this finding is restricted by the low quality of the included SRs/MAs. And more high-quality and large-sample studies are needed in the future.

PROSPERO

ID: CRD42022322768. https://www.crd.york.ac.uk/prospero/#recordDetails.

The effectiveness of home-based balance and pulmonary rehabilitation program in individuals with chronic obstructive pulmonary disease: a randomized controlled trial

BACKGROUND

Balance impairment and increased fall risk have been demonstrated in individuals with chronic obstructive pulmonary disease (COPD). However, studies investigating the effects of balance training especially when combined with pulmonary rehabilitation (PR) program in home-based setting are scarce.

AIM

To examine whether adding balance training to home-based pulmonary rehabilitation improves balance, fall risk, and disease-related symptoms in individuals with COPD.

DESIGN

Randomized, controlled, assessor-blinded trial with parallel two-group design.

SETTING

Home-based setting.

POPULATION

Forty-eight individuals diagnosed with COPD.

METHODS

Participants with COPD were randomly allocated to either a home-based PR or home-based balance training combined with PR (PR-BT) group (24 per group). Both groups exercised three days per week for eight-week. Primary outcomes were fall risk index and functional balance as measured by the Physiological Profile Assessment (PPA) and Timed Up and Go (TUG), respectively. Secondary outcomes were the Activities-specific Balance Confidence (ABC), Modified Medical Research Council dyspnea (mMRC), Six-Minute Walk Test (6MWT), and COPD assessment test (CAT). All outcome measures were assessed at baseline, post-intervention, and three-month follow-up.

RESULTS

All participants completed the trial, with no reported adverse events. At post-intervention, the PR-BT group demonstrated significantly greater improvements in PPA fall risk score (PR-BT: 1.1±0.8, PR: 2.4±1.5), TUG (PR-BT: 10.7±1.3, PR: 14.4±4.4 s) and these improvements remained at three-month follow-up (all P<0.01). The ABC, mMRC, and CAT scores were also significant better for the PR-BT than the PR group both after intervention and at three-month follow-up (all P<0.05).

CONCLUSIONS

Eight-week home-based balance and PR program is effective in improving balance as well as dyspnea, and well-being in individuals with COPD.

CLINICAL REHABILITATION IMPACT

Home-based balance and PR program is a promising approach for COPD rehabilitation especially in patients who are at risk of falls.

Sarcopenia definition: Does it really matter? Implications for resistance training

The loss of muscle mass, strength and function, known as sarcopenia, is common in older adults, and is associated with falls, fractures, cardiometabolic diseases, and lower quality of life. Sarcopenia can also occur secondarily to chronic diseases. Recently, sarcopenia was recognized as a disease with an International Classification of Disease (ICD) code, yet, at least five definitions for its clinical identification exist. Most definitions include three themes: low muscle mass, strength and physical performance. However, the definitions vary by the number of themes needed to diagnose sarcopenia and, within each theme various parameters and cut-off levels exist. The lack of consensus on what constitutes a diagnosis can create confusion and hesitation in sarcopenia diagnosis. Currently, no pharmacological treatment exists for sarcopenia. Resistance training (RT) is safe and effective to improve muscle mass, strength and physical performance in older adults and clinical populations. Based on current guidelines, whether an individual is defined as "sarcopenic", or not, does not change the way RT is prescribed. Here, we present evidence and the inconsistencies in sarcopenia definitions and recommend that focus should be on optimizing ways to prescribe RT and increase long-term adherence, rather than on slight modifications to sarcopenia definitions.

Examining the repeatability of a novel test to measure exertional dyspnoea in chronic obstructive pulmonary disease

BACKGROUND

Exertional dyspnoea(ED) is a hallmark of chronic obstructive pulmonary disease(COPD). We examined the repeatability and face validity of the end-exercise ED(ED_end) response during the Dyspnoea Challenge and compared those to the six-minute walk test (6MWT) in COPD.

METHODS

Twenty-six individuals with COPD(13 Females, age:69 ± 5.5yrs, FEV₁:63.4 ± 11.9 %) completed 2 × 6MWTs and 4 x Dyspnoea Challenges on three occasions. The challenge consisted of a two-minute treadmill walk at 80 % of 6MWT speed(3.9 ± 0.5 km·hr^-1) at either a low(LI_DC:5.3 ± 2%) or high angle of incline(HI_DC:9.5 ± 3%). Dyspnoea(0-10 scale), heart rate(HR) and oxygen saturation(S_pO₂) were monitored continuously.

RESULTS

Mean 6MWT distance was 488 ± 58 m. End-exercise ED and HR were higher in the HI_DC(ED_end 6.2 ± 2.0; HR: 123 ± 17beats·min^-1) compared to the LI_DC(ED_end 4.2 ± 2.0; HR: 119 ± 15beats·min^-1) and the 6MWT(ED_end 4.3 ± 2.0; HR: 115 ± 16beats·min^-1)(P < 0.01). SpO₂ was not different between 6MWT, LI_DC or HI_DC(P = 0.34). The intraclass correlation coefficient(ICC) for each intensity was excellent (HI_DC, ICC = 0.88, LI_DC, ICC = 0.93, P < 0.001) with neither reporting bias(HI_DC, P = 0.63; LI_DC, P = 0.94).

CONCLUSIONS

The Dyspnoea Challenge is a simple measure of ED that appears to have both repeatability and face validity. With further optimisation, this test may enhance the field-based clinical assessment of ED.

Measuring intensity during free-living physical activities in people with chronic obstructive pulmonary disease: a systematic literature review

BACKGROUND

Measuring intensity of physical activity (PA) is important to ensure safety and the effectiveness of PA interventions in chronic obstructive pulmonary disease (COPD).

OBJECTIVE

This systematic review identified which outcomes, outcome measures and instruments have been used to assess single free-living PA-related intensity in people with COPD and compared the intensity level (light, moderate, vigorous) obtained by different outcome measures.

METHODS

PubMed, Scopus, Web of Science, Cochrane Library and EBSCO were searched for original studies of COPD and assessing single free-living PA-related intensity were included. Agreement was calculated as the number of agreements between 2 measures [same intensity level]/ number of comparisons using both measures*100.

RESULTS

We included 43 studies (1282 people with COPD, mean age 66 years, 65% men, 49% FEV_1%pred) and identified 13 outcomes, 46 outcome measures and 22 instruments. The most-reported outcomes, outcome measures and instruments were dyspnoea with the Borg scale 0-10; cardiac function, via heart rate (HR) using HR monitors; and pulmonary gas exchange, namely oxygen consumption (VO₂), using portable gas analysers, respectively. The most frequently assessed PAs were walking and lifting, changing or moving weights/objects. Agreement between the outcome measures ranged from 0 (%VO_2peak vs metabolic equivalent of task [MET]; %HR_peak vs Fatigue Borg; MET vs walking speed) to 100% (%HR_reserve vs dyspnoea Borg; fatigue and exertion Borg vs walking speed). %VO_{2peak/reserve} elicited the highest intensity. Hence, Borg scores, %HR_reserve and MET may underestimate PA-related intensity.

CONCLUSIONS

Various methodologies are used to assess single free-living PA-related intensity and yield different intensity levels for the same PA. Future studies, further exploring the agreement between the different outcome measures of PA-related intensity and discussing their advantages, disadvantages and applicability in real-world settings, are urgent. These would guide future worldwide recommendations on how to assess single free-living PA-related intensity in COPD, which is essential to optimise PA interventions and ensure patient safety.