The prevalence of quadriceps weakness in COPD and the relationship with disease severity

Segmental phase angle can predict incidence of severe exacerbation in male patients with COPD

OBJECTIVE

To investigate whether segmental phase angle (PhA) is a useful predictor of severe chronic obstructive pulmonary disease (COPD) exacerbation.

RESEARCH METHODS AND PROCEDURES

This prospective cohort study enrolled consecutive patients with COPD with a follow-up period of 3 years. The primary outcome was incidence of severe exacerbation. PhA was measured for the whole body and segmental body sites (trunk and upper and lower limbs). We used receiver operating characteristic (ROC) curves to determine the cut-off values and area under the curve (AUC) for predicting exacerbation based on PhA. We applied Cox proportional hazard regression analyses to estimate the independent prognostic effect of PhA on the incidence of severe exacerbation.

RESULTS

We analyzed 108 male participants (mean age 75.1±7.9 years) and the median follow-up period was 1082 [643-1103] days, with an annual severe exacerbation incidence rate of 0.23 per person-year. ROC analysis revealed that the AUC for Whole-body and segmental PhA were as follows: Whole-body: AUC = 0.69 (95% confidence interval [CI] = 0.59-0.79); right arm: AUC = 0.65 (95% CI = 0.53-0.77); left arm: AUC = 0.68 (95% CI = 0.56-0.79); right leg: AUC = 0.73 (95% CI = 0.64-0.82); left leg: AUC = 0.71 (95% CI = 0.62-0.81); trunk: AUC = 0.58 (95% CI = 0.46-0.69). Cox proportional hazard analysis demonstrated that PhA of the right leg (hazard ratio [HR]=3.50, 95% CI=1.33-9.20), left leg (HR=3.26, 95% CI=1.18-9.04), and left arm (HR=2.61, 95% CI=1.17-6.80) were independently and significantly associated with incidence of severe exacerbation. Whole and trunk PhA were not significantly associated with the incidence of severe exacerbation.

CONCLUSIONS

Segmental PhA may serve as a valuable predictive indicator of severe exacerbation in male patients with COPD. Notably, both leg PhA were strongly associated with the occurrence of severe exacerbations.

REGISTRY NUMBER

UMIN000044824.

Shear wave elastography, as a feasible tool, can be used to reflect the lower limb dysfunction in patients with chronic obstructive pulmonary disease?

To explore the additional value of shear wave elastography (SWE) in chronic obstructive pulmonary disease (COPD) patients. Ultrasound elastography of the rectus femoris and patellar tendon was performed to determine the mean elasticity index (SWEmean) of the rectus femoris (SWERF) and patellar tendon (SWEPT) in 56 patients with COPD and 53 healthy controls. Clinical tests included the COPD Assessment Test (CAT), the dyspnea index score (modified British Medical Research Council (mMRC)score), the Five-Repetition Sit-to-Stand Test(5STS) and the Six-Minute Walk Test (6MWT). We compared differences in SWEmean between healthy controls and COPD patients while describing the correlation between SWEmean and clinical tests in COPD patients. Both the intra-observer and inter-observer repeatability of SWE performance were excellent (all correlation coefficients > 0.75; p < 0.05). There was a statistically significant difference between healthy controls and COPD patients in the SWERF and SWEPT between healthy controls and COPD patients (p < 0.001). The COPD patients had smaller SWERF and larger SWEPT than healthy controls. The SWERF was positively correlated with the 6MWT (r = 0.591, p < 0.001), and negatively related to the mMRC (r = - 0.794, p < 0.001), CAT (r = - 0.894, p < 0.001) and 5STS (r = - 0.928, p < 0.001). But the SWEPT was positively related to the 6MWT (r = 0.269, p < 0.05), mMRC (r = 0.398, p < 0.05), CAT (r = 0.377, p < 0.05) and 5STS (r = 0.332, p < 0.05). SWEmean of COPD patients was statisticant, different from that of healthy controls, and associated with clinical tests. SWE was a simple and feasible tool for reflecting the lower limb dysfunction in patients with COPD.

Concordance of Freehand 3D Ultrasound Muscle Measurements With Sarcopenia Parameters in a Geriatric Rehabilitation Ward

BACKGROUND

Sarcopenia is a devastating disease for older adults, but it lacks accessible and reliable tools for measuring total appendicular skeletal muscle mass (ASMM). Two-dimensional muscle ultrasound (US) has been developed for its bedside clinical advantages and feasibility but lacks standardization and prediction performance. We previously validated a new 3D-US technique to measure muscle volume (MV) at bedside and applied it in a geriatric rehabilitation setting. Objectives were to analyse the concordance between 3D-US MV and ASMM and compare concordance between 3D-US MV and 2D-US parameters with ASMM.

METHODS

Participants were recruited in a Geriatric rehabilitation ward in Nantes, France, from May to October 2022. Exclusion criteria were as follows: oedema in the lower limbs or recent history of unilateral lower limb damage or stroke. ASMM was measured with bioelectrical impedance analysis; 3D-US and 2D-US acquisitions were performed on three muscles of the right lower limb. Measures of strength (hand grip, knee extension and ankle dorsiflexion) were also recorded. Reliability of 3D-US MV measurements on 10 participants was high (ICC = 0.99). We used Lin's concordance correlation coefficients (CCC) and bias correction factor for agreement between variables and linear regression models for prediction equations.

RESULTS

Fifty-eight participants had an interpretable ASMM of whom 17 (29%) had a diagnosis of sarcopenia. Volumes of TA, RF and VL were all significantly concordant with ASMM measured by BIA (all p values < 0.001), with CCCs respectively of 0.72, 0.61 and 0.60. MV were all significantly concordant with isometric strength (p values < 0.001). Concordance and correlation with ASMM were higher with 3D-US than 2D-US measurements regardless of the muscle. Prediction of ASMM reached an adjusted R2 of 0.8 with tibialis anterior volume, biometrics and 2D measurements.

CONCLUSIONS

This study was the first to use 3D-US in a geriatric setting and develop a model to predict ASMM in very old hospitalized patients. MV measurements with 3D-US proved to be reliable and more concordant with appendicular muscle mass and strength than 2D parameters.

Clinical Implications of Functional Imaging in the Assessment of Bronchiectasis-Associated Sarcopenia

INTRODUCTION

Bronchiectasis is a complex lung disease with poorly studied systemic manifestations. Patients with bronchiectasis-associated sarcopenia exhibit a specific differential profile of functional muscle phenotype (vastus lateralis, VL), which may be analyzed using imaging (ultrasound and magnetic resonance imaging, MRI).

METHODS

Ultrasound and MRI were used to explore functional imaging parameters in quadriceps of 20 patients with stable bronchiectasis and 10 healthy controls. In muscle specimens (open biopsy procedures), muscle phenotype (fiber morphometry and structural abnormalities, immunohistochemistry) was also evaluated. Patients and controls were clinically and functionally evaluated.

RESULTS

In muscles of patients compared to controls, a significant decline in body composition parameters (BMI and FFMI), muscle function (upper and lower limbs), lung function, and exercise capacity was detected, ultrasonography revealed decreased muscle thickness and area, while MRI demonstrated increased fat infiltration, which positively correlated with the bronchiectasis severity scores. Structural parameters (proportions of hybrid fibers, internal nuclei, abnormal fibers, and apoptotic nuclei) were significantly greater in the VL of patients than in controls and inversely correlated with quadriceps muscle function and exercise capacity in the former.

CONCLUSIONS

In patients with stable mild-to-moderate bronchiectasis, sarcopenia was clinically evidenced through the significant reduction in muscle mass and upper and lower limb muscle function. Non-invasive ultrasound and MRI techniques showed that features of muscle quality architecture and fat infiltration are hallmarks of bronchiectasis-associated sarcopenia. Functional radiological tools should be implemented in clinical settings to early diagnose and monitor sarcopenia in these patients.

Effect of exercise interventions on oxygen uptake in people with chronic obstructive pulmonary disease: A network meta-analysis of randomized controlled trials

BACKGROUND

Although aerobic training leads to physiological improvements in people with chronic obstructive pulmonary disease (COPD), measured by the VO2 peak, there is no evidence as to which type of physical exercise intervention is the most effective in improving the VO2 peak or max.

OBJECTIVE

A network meta-analysis (NMA) was performed to determine the effects of different physical interventions on oxygen uptake in people with COPD.

METHODS

A literature search was performed from database inception to February 2024. Randomized controlled trials on the effectiveness of exercise programs on oxygen uptake with COPD were included. We assessed the risk of bias using the Cochrane Risk of Bias (RoB 2.0) tool and the quality of the evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool. Pairwise meta-analyses and NMAs were performed for direct and indirect evidence.

RESULTS

A total of 22 studies were included in this NMA. The highest effects for improvement in oxygen uptake scores were for continuous, moderate-intensity endurance exercise versus a control (effect size [ES]: 1.17; 95% CI 0.59 to 1.74), followed by continuous, high-intensity endurance exercise versus a control (ES: 0.47; 95% CI 0.08 to 0.85), and combined exercise versus a control (ES: 0.41; 95% CI 0.18 to 0.64).

CONCLUSIONS

Continuous, moderate-intensity endurance exercise should be considered the most effective strategy to improve oxygen uptake in people with COPD, followed by continuous, high-intensity endurance exercise and combined exercise. Due to the importance of VO2 as a predictor of quality of life and mortality in people with COPD, it is essential to include its assessment in clinical guidelines and to include the most effective physical activity interventions to improve it.

TRIAL REGISTRATION

PROSPERO database: CRD42023425893.

Mitochondrial free radicals contribute to cigarette smoke condensate-induced impairment of oxidative phosphorylation in the skeletal muscle in situ

Oxidative stress plays a critical role in cellular dysfunction associated with cigarette smoke exposure and aging. Some chemicals from tobacco smoke have the potential to amplify mitochondrial ROS (mROS) production, which, in turn, may impair mitochondrial respiratory function. Accordingly, the present study tested the hypothesis that a mitochondria-targeted antioxidant (MitoTEMPO, MT) would attenuate the inhibitory effects of cigarette smoke on skeletal muscle respiratory capacity of middle-aged mice. Specifically, mitochondrial oxidative phosphorylation was assessed using high-resolution respirometry in permeabilized fibers from the fast-twitch gastrocnemius muscle of middle-aged C57Bl/6J mice. Before the assessment of respiration, tissues were incubated for 1hr with a control buffer (CON), cigarette smoke condensate (2 % dilution, SMOKE), or MitoTEMPO (10 μM) combined with cigarette smoke condensate (MT + SMOKE). Cigarette smoke condensate (CSC) decreased maximal-ADP stimulated respiration (CON: 60 ± 15 pmolO2.s-1.mg-1 and SMOKE: 33 ± 8 pmolO2.s-1.mg-1; p = 0.0001), and this effect was attenuated by MT (MT + SMOKE: 41 ± 7 pmolO2.s-1.mg-1; p = 0.02 with SMOKE). Complex-I specific respiration was inhibited by CSC, with no significant effect of MT (p = 0.35). Unlike CON, the addition of glutamate (ΔGlutamate) had an additive effect on respiration in fibers exposed to CSC (CON: 0.9 ± 1.1 pmolO2.s-1.mg-1 and SMOKE: 5.4 ± 3.7 pmolO2.s-1.mg-1; p = 0.008) and MT (MT + SMOKE: 8.2 ± 3.8 pmolO2.s-1.mg-1; p ≤ 0.01). Complex-II specific respiration was inhibited by CSC but was partially restored by MT (p = 0.04 with SMOKE). Maximal uncoupled respiration induced by FCCP was inhibited by CSC, with no significant effect of MT. These findings underscore that mROS contributes to cigarette smoke condensate-induced inhibition of mitochondrial respiration in fast-twitch gastrocnemius muscle fibers of middle-aged mice thus providing a potential target for therapeutic treatment of smoke-related diseases. In addition, this study revealed that CSC largely impaired muscle respiratory capacity by decreasing metabolic flux through mitochondrial pyruvate transporter (MPC) and/or the enzymes upstream of α-ketoglutarate in the Krebs cycle.

Association of computed tomography-derived pectoralis muscle area and density with disease severity and respiratory symptoms in patients with chronic obstructive pulmonary disease: A case-control study

RATIONALE AND OBJECTIVES

Computed tomography (CT) is commonly used and offers an additional viewpoint for evaluating extrapulmonary symptoms, disease severity, and muscle atrophy. This study assessed whether the pectoralis muscle area (PMA) and pectoralis muscle density (PMD) are lower in patients with chronic obstructive pulmonary disease (COPD) than in healthy controls and elucidated their relationships with these variables.

MATERIALS AND METHODS

The participants were enrolled in the hospital outpatient clinic between October 2023 and May 2024. Information was obtained from questionnaires, lung function, and CT imaging findings. On full-inspiratory CT, the PMA and PMD were measured at the aortic arch level using predetermined attenuation ranges of -29 and 150 Hounsfield units. We observed lower PMA and PMD and evaluated their associations with lung function, respiratory symptoms, and CT imaging findings in patients with COPD.

RESULTS

Overall, 120 participants were enrolled at baseline (60 healthy controls and 60 patients with COPD). PMA and PMD were lower with progressive airflow limitation severity in those with COPD. The degree of emphysema and air trapping, as well as lung function, were correlated with PMA and PMD (P < 0.05), although not with the COPD Assessment Test or modified Medical Research Council scores (P > 0.05).

CONCLUSION

Participants with COPD had smaller PMA and PMD. These measurements were correlated with the severity of airflow limitation, lung function, emphysema, and air trapping, suggesting that these features of the pectoralis muscle obtained from CT are helpful in assessments of patients with COPD.

An Italian Delphi Consensus on the Triple inhalation Therapy in Chronic Obstructive Pulmonary Disease

BACKGROUND

The management of chronic obstructive pulmonary disease (COPD) lacks standardization due to the diverse clinical presentation, comorbidities, and limited acceptance of recommended approaches by physicians. To address this, a multicenter study was conducted among Italian respiratory physicians to assess consensus on COPD management and pharmacological treatment.

METHODS

The study employed the Delphi process using the Estimate-Talk-Estimate method, involving a scientific board and expert panel. During a 6-month period, the scientific board conducted the first Delphi round and identified 11 broad areas of COPD management to be evaluated while the second Delphi round translated all 11 items into statements. The statements were subsequently presented to the expert panel for independent rating on a nine-point scale. Consensus was considered achieved if the median score was 7 or higher. Consistently high levels of consensus were observed in the first rating, allowing the scientific board to finalize the statements without requiring further rounds.

RESULTS

Topics generating substantial discussion included the pre-COPD phase, patient-reported outcomes, direct escalation from a single bronchodilator to triple therapy, and the role of adverse events, particularly pneumonia, in guiding triple therapy prescriptions. Notably, these topics exhibited higher standard deviations, indicating greater variation in expert opinions.

CONCLUSIONS

The study emphasized the significance that Italian pulmonologists attribute to managing mortality, tailoring treatments, and addressing cardiovascular comorbidities in COPD patients. While unanimous consensus was not achieved for all statements, the results provide valuable insights to inform clinical decision-making among physicians and contribute to a better understanding of COPD management practices in Italy.

Cigarette smoke exposure impairs early-stage recovery from lengthening contraction-induced muscle injury in male mice

The use of tobacco cigarettes produces locomotor muscle weakness and fatigue intolerance. Also, smokers and chronic obstructive pulmonary disease patients have a greater incidence of muscle injury and a deficient myogenic response. However, the effects of smoke exposure on the recovery from eccentric exercise-induced muscle injuries are unknown. Mice were exposed daily to cigarette smoke (CS) or room air (Air) for 4 months; the anterior crural muscles from one limb were injured by a lengthening contractions protocol (LCP) and recovered for 7 days. Lung compliance was greater, and body weights were lower, in CS-exposed than in the Air group. In LCP-subjected limbs, CS exposure lowered tibialis anterior myofiber cross-sectional area, decreased the size of centrally nucleated myofibers, and decreased extensor digitorum longus (EDL) mass, but did not affect EDL force from both limbs. CS exposure upregulated the mRNA levels of several myogenic (Pax7, Myf5, nNOS) genes in the EDL. The combination of CS exposure and LCP decreased Myf5 and nNOS mRNA levels and exacerbated pro-inflammatory mRNA levels. These data suggest that smoke exposure leads to an excessive pro-inflammatory response in regenerating muscle that is associated with a lower muscle mass recovery from a type of injury that often occurs during strenuous exercise.

Transcriptomic analysis reveals distinct effects of cigarette smoke on murine airspace and bone-marrow derived macrophages

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an inflammatory airway disease characterized by emphysema and chronic bronchitis and a leading cause of mortality worldwide. COPD is commonly associated with several comorbid diseases which contribute to exacerbated patient outcomes. Cigarette smoke (CS) is the most prominent risk factor for COPD development and progression and is known to be detrimental to numerous effector functions of lung resident immune cells, including phagocytosis and cytokine production. However, how CS mediates the various pathologies distant from the lung in COPD, and whether CS has a similar biological effect on systemic immune cells remains unknown.

METHODS

C57BL/6 mice were exposed to 8 weeks of CS as an experimental model of COPD. Bone marrow cells were isolated from both CS-exposed and room air (RA) control mice and differentiated to bone marrow-derived macrophages (BMDMs). Airspace macrophages (AMs) were isolated from the same CS-exposed and RA mice and bulk RNA-Seq performed. The functional role of differentially expressed genes was assessed through gene ontology analyses. Ingenuity Pathway Analysis was used to determine the activation states of canonical pathways and upstream regulators enriched in differentially expressed genes in both cell types, and to compare the differences between the two cell types.

RESULTS

CS induced transcriptomic changes in BMDMs, including an upregulation of genes in sirtuin signalling and oxidative phosphorylation pathways and a downregulation of genes involved in histone and lysine methylation. In contrast, CS induced decreased expression of genes involved in pathogen response, phagosome formation, and immune cell trafficking in AMs. Little overlap was observed in differentially expressed protein-coding genes in BMDMs compared to AMs and their associated pathways, highlighting the distinct effects of CS on immune cells in different compartments.

CONCLUSIONS

CS exposure can induce transcriptomic remodelling in BMDMs which is distinct to that of AMs. Our study highlights the ability of CS exposure to affect immune cell populations distal to the lung and warrants further investigation into the functional effects of these changes and the ensuing role in driving multimorbid disease.

Longitudinal change in ultrasound-derived rectus femoris cross-sectional area in COPD

Background

Skeletal muscle dysfunction is common in COPD. Ultrasound-derived rectus femoris cross-sectional area (RFCSA) is a radiation free, non-invasive measure of muscle bulk that relates to quadriceps strength in people with COPD. However, there are limited longitudinal data for RFCSA, and it is not known whether longitudinal change in RFCSA reflects change in quadricep strength, exercise capacity, lower limb function or muscle mass. We aimed to quantify longitudinal change in ultrasound-derived RFCSA and assess its relationship with change in quadriceps maximal voluntary contraction (QMVC), incremental shuttle walk test (ISWT), five-repetition sit-to-stand (5STS) and fat-free mass (FFM) over 12 months in people with COPD.

Methods

We measured ultrasound-derived RFCSA, QMVC, ISWT, 5STS and FFM (measured by bioelectric impedance analysis) at baseline and 12 months in 169 people with stable COPD. Change was correlated using Pearson's or Spearman's coefficients.

Results

Baseline characteristics: mean±sd age 70.4±9.4 years; FEV1 53.3±18.9% predicted. Over the course of 12 months mean RFCSA change was -33.7 mm2 (99% CI -62.6- -4.9 mm2; p=0.003) representing a mean±sd percentage change of -1.8±33.5%. There was a weak correlation between change in RFCSA and FFM (r=0.205, p=0.009), but not with change in QMVC, ISWT or 5STS.

Conclusion

There is a statistically significant decrease in ultrasound-derived RFCSA over 12 months in people with stable COPD, but this decrease does not correlate with change in quadriceps strength, exercise capacity, FFM or lower limb function.

Functional capacity using sit-to-stand tests in people with chronic obstructive pulmonary disease and its relationship with disease severity-a cross-sectional study with matched controls

BACKGROUND

Functional capacity impairment is a crucial consequence of chronic obstructive pulmonary disease (COPD). Although it can be identified with simple tests, such as the sit-to-stand tests, its prevalence, relation with disease severity, and the characteristics of people presenting this impairment remain unknown.

OBJECTIVE

To explore the functional capacity of people with COPD.

METHODS

A cross-sectional study with people with COPD and age-/sex-matched healthy controls was conducted. Functional capacity was assessed with the 5-repetitions (5-STS) and the 1-minute (1-minSTS) sit-to-stand tests. People with COPD were grouped according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classifications. Comparisons between people with COPD and healthy controls, and among GOLD groups were established. Associations between symptoms, muscle strength, quality of life, and measures of functional capacity were explored.

RESULTS

302 people with COPD [79% male; mean (SD) 68 (10) years old] and 304 healthy controls [75% male; 66 (9) years old] were included. 23% of people with COPD presented impairment in the 5-STS and 33% in the 1-minSTS. People with COPD from all GOLD classifications presented significantly lower functional capacity than healthy controls (5-STS: COPD median [1st quartile; 3rd quartile] 8.4 [6.7; 10.6] versus healthy 7.4 [6.2; 9.3] s; 1-minSTS: COPD 27 [21; 35] vs healthy 35 [29; 43] reps). Correlations with symptoms, muscle strength, and quality of life were mostly weak (5-STS: rs [-0.34; 0.33]; 1-minSTS: rs [-0.47; 0.40]).

CONCLUSION

People with COPD have decreased functional capacity independently of their GOLD classifications. The prevalence of functional impairment is 23-33%. Because impaired functional capacity is a treatable trait not accurately reflected by other outcomes, comprehensive assessment and management is needed.

The impact of chronic obstructive pulmonary disease on bone strength

Chronic obstructive pulmonary disease (COPD) is a lifestyle-related disease that develops in middle-aged and older adults, often due to smoking habits, and has been noted to cause bone fragility. COPD is a risk factor for osteoporosis and fragility fracture, and a high prevalence of osteoporosis and incidence of vertebral fractures have been shown in patients with COPD. Findings of lung tissue analysis in patients with COPD are primarily emphysema with a loss of alveolar septal walls, and the severity of pulmonary emphysema is negatively correlated with thoracic spine bone mineral density (BMD). On the other hand, epidemiological studies on COPD and fracture risk have reported a BMD-independent increase in fracture risk; however, verification in animal models and human bone biopsy samples has been slow, and the essential pathogenesis has not been elucidated. The detailed pathological/molecular mechanisms of musculoskeletal complications in patients with COPD are unknown, and basic research is needed to elucidate the mechanisms. This paper discusses the impacts of COPD on bone strength, focusing on findings in animal models in terms of bone microstructure, bone metabolic dynamics, and material properties.

Roles of pigment epithelium-derived factor in exercise-induced suppression of senescence and its impact on lung pathology in mice

Senescent cells contribute to tissue aging and underlie the pathology of chronic diseases. The benefits of eliminating senescent cells have been demonstrated in several disease models, and the efficacy of senolytic drugs is currently being tested in humans. Exercise training has been shown to reduce cellular senescence in several tissues; however, the mechanisms responsible remain unclear. We found that myocyte-derived factors significantly extended the replicative lifespan of fibroblasts, suggesting that myokines mediate the anti-senescence effects of exercise. A number of proteins within myocyte-derived factors were identified by mass spectrometry. Among these, pigment epithelium-derived factor (PEDF) exerted inhibitory effects on cellular senescence. Eight weeks of voluntary running increased Pedf levels in skeletal muscles and suppressed senescence markers in the lungs. The administration of PEDF reduced senescence markers in multiple tissues and attenuated the decline in respiratory function in the pulmonary emphysema mouse model. We also showed that blood levels of PEDF inversely correlated with the severity of COPD in patients. Collectively, these results strongly suggest that PEDF contributes to the beneficial effects of exercise, potentially suppressing cellular senescence and its associated pathologies.

Effect of Home-Based Pulmonary Rehabilitation on Pulmonary Fibrosis

BACKGROUND

Pulmonary fibrosis is a chronic, progressive lung condition that involves lung tissue scarring and thickening. The effects of home-based pulmonary rehabilitation (PR) in post-covid pulmonary fibrosis (PCPF) and other forms of fibrosis together have not been evaluated. This study aims to evaluate the effectiveness of home-based pulmonary rehabilitation on pulmonary function, functional capacity, and health-related quality of life in people with pulmonary fibrosis (post-COVID pulmonary fibrosis, pulmonary fibrosis secondary to pulmonary tuberculosis (TB), pulmonary fibrosis secondary to interstitial lung disease (ILD), pulmonary fibrosis secondary to bronchiectasis).

METHODS

A single-group pretest-posttest experimental study was performed after recruiting 98 pulmonary fibrosis subjects from K.M.C hospitals. After being screened for the inclusion and exclusion criteria, 45 subjects were analyzed, and 6 subjects were lost to follow-up.  A home-based pulmonary rehabilitation program was carried out for 8 weeks (warm-up, stretching exercises, aerobic exercise, strength training for upper limb and lower limb, breathing exercises mainly involved; others: energy saving techniques, controlled coughing techniques, dyspnea relieving positions). The program was supervised via weekly phone calls. Pulmonary function (Pulmonary function test), exercise capacity (6-minute walk test), dyspnea (modified Borg scale), and health-related quality of life (SF-36) were evaluated before and after the intervention. During the enrollment and after the 6-minute walk test, saturation of peripheral oxygen (SPO2) level was also evaluated pre-intervention and after the 8-weeks program.

RESULTS

Pulmonary function [FVC(L) t = -12.52, p<0.05; FEV1(L) t = -2.56, p<0.05; FEV1/FVC t = 7.98, p<0.05 and DLCO (ml/min/mmHg) t = -5.13, p<0.05], 6MWD [MD 88.66; p<0.05] and HRQOL measured by SF-36 scores (p<0.05) were improved significantly. Both the baseline SPO2 level before the 6MWT [MD 1.07, p<0.05] and the SPO2 level after the 6MWT [MD 1.16, p<0.05] showed a significant improvement. The rating of perceived exertion(dyspnea) [MD 1.30, p<0.05] was reduced significantly after the 8-week program.

CONCLUSION

Our study shows that home-based pulmonary rehabilitation is an effective option for improving lung function and physical functional capacity by reducing dyspnea perception and improving the saturation of peripheral oxygen (SPO2) level, and enhancing the quality of life in people with pulmonary fibrosis.

Unravelling the complex interplay of factors behind exercise limitations and physical inactivity in COPD

Exercise limitation and physical inactivity are known treatable traits for people with COPD. Maximising exercise capacity and keeping people physically active improves health status and survival rates among people with COPD. However, managing these two treatable traits can be extremely challenging for clinicians due to the complex intersectionality of factors influencing an individual's capacity, opportunity and motivation to engage in physical activity. This review presents the complex factors influencing exercise capacity ("can do"), levels of physical activity ("do do") and sedentary behaviours amongst people with COPD and provides practical recommendations on how clinicians can address some of these factors in practice. Most importantly, it highlights the importance of referring to pulmonary rehabilitation as a way to improve exercise capacity among people with COPD.

Effects of Ninjin'yoeito on Patients with Chronic Obstructive Pulmonary Disease and Comorbid Frailty and Sarcopenia: A Preliminary Open-Label Randomized Controlled Trial

Purpose

To present the preliminarily findings regarding the effects of a herbal medicine, Ninjin'yoeito, on comorbid frailty and sarcopenia in patients with chronic obstructive pulmonary disease (COPD).

Patients and Methods

Patients with COPD (GOLD II or higher) and fatigue were randomly assigned to Group A (n = 28; no medication for 12 weeks, followed by 12-week administration) or B (n= 25; 24-week continuous administration). Visual analog scale (VAS) symptoms of fatigue, the COPD assessment test (CAT), and the modified Medical Research Council (mMRC) Dyspnea Scale were examined. Physical indices such asknee extension leg strength and walking speed, skeletal muscle mass index (SMI), and respiratory function test were also measured.

Results

VAS fatigue scales in Group B significantly improved after 4, 8, and 12 weeks compared to those in Group A (each p<0.001, respectively). Right and left knee extension leg strength in Group B significantly improved after 12 weeks compared to that in Group A (p=0.042 and p=0.037, respectively). The 1-s walking speed for continued to increase significantly over 24 weeks in Group B (p=0.016, p<0.001, p<0.001, p=0.004, p<0.001, and p<0.001 after 4, 8, 12, 16, 20, and 24 weeks, respectively); it also significantly increased after the administration of Ninjin'yoeito in Group A. In Group B, the SMI significantly increased at 12 weeks in patients with sarcopenia (p=0.025). The CAT scores in Group B significantly improved after 12 weeks compared to those in Group A (p=0.006). The mMRC scores in Group B also significantly improved after 8 and 12 weeks compared to those in Group A (p= 0.045 and p <0.001, respectively). The changes in %FEV1.0 in Group B were significantly improved at 12 and 24 weeks (p=0.039 and p=0.036, respectively).

Conclusion

Overall, Ninjin'yoeito significantly improved patients' quality of life, physical activity, muscle mass, and possibly lung function, suggesting that Ninjin'yoeito may improve frailty and sarcopenia in patients with COPD.

Musculoskeletal crosstalk in chronic obstructive pulmonary disease and comorbidities: Emerging roles and therapeutic potentials

Chronic Obstructive Pulmonary Disease (COPD) is a multifaceted respiratory disorder characterized by progressive airflow limitation and systemic implications. It has become increasingly apparent that COPD exerts its influence far beyond the respiratory system, extending its impact to various organ systems. Among these, the musculoskeletal system emerges as a central player in both the pathogenesis and management of COPD and its associated comorbidities. Muscle dysfunction and osteoporosis are prevalent musculoskeletal disorders in COPD patients, leading to a substantial decline in exercise capacity and overall health. These manifestations are influenced by systemic inflammation, oxidative stress, and hormonal imbalances, all hallmarks of COPD. Recent research has uncovered an intricate interplay between COPD and musculoskeletal comorbidities, suggesting that muscle and bone tissues may cross-communicate through the release of signalling molecules, known as "myokines" and "osteokines". We explored this dynamic relationship, with a particular focus on the role of the immune system in mediating the cross-communication between muscle and bone in COPD. Moreover, we delved into existing and emerging therapeutic strategies for managing musculoskeletal disorders in COPD. It underscores the development of personalized treatment approaches that target both the respiratory and musculoskeletal aspects of COPD, offering the promise of improved well-being and quality of life for individuals grappling with this complex condition. This comprehensive review underscores the significance of recognizing the profound impact of COPD on the musculoskeletal system and its comorbidities. By unravelling the intricate connections between these systems and exploring innovative treatment avenues, we can aspire to enhance the overall care and outcomes for COPD patients, ultimately offering hope for improved health and well-being.

Body composition impacts outcome of bronchoscopic lung volume reduction in patients with severe emphysema: a fully automated CT-based analysis

Chronic Obstructive Pulmonary Disease (COPD) is characterized by progressive and irreversible airflow limitation, with individual body composition influencing disease severity. Severe emphysema worsens symptoms through hyperinflation, which can be relieved by bronchoscopic lung volume reduction (BLVR). To investigate how body composition, assessed through CT scans, impacts outcomes in emphysema patients undergoing BLVR. Fully automated CT-based body composition analysis (BCA) was performed in patients with end-stage emphysema receiving BLVR with valves. Post-interventional muscle and adipose tissues were quantified, body size-adjusted, and compared to baseline parameters. Between January 2015 and December 2022, 300 patients with severe emphysema underwent endobronchial valve treatment. Significant improvements were seen in outcome parameters, which were defined as changes in pulmonary function, physical performance, and quality of life (QoL) post-treatment. Muscle volume remained stable (1.632 vs. 1.635 for muscle bone adjusted ratio (BAR) at baseline and after 6 months respectively), while bone adjusted adipose tissue volumes, especially total and pericardial adipose tissue, showed significant increase (2.86 vs. 3.00 and 0.16 vs. 0.17, respectively). Moderate to strong correlations between bone adjusted muscle volume and weaker correlations between adipose tissue volumes and outcome parameters (pulmonary function, QoL and physical performance) were observed. Particularly after 6-month, bone adjusted muscle volume changes positively corresponded to improved outcomes (ΔForced expiratory volume in 1 s [FEV1], r = 0.440; ΔInspiratory vital capacity [IVC], r = 0.397; Δ6Minute walking distance [6MWD], r = 0.509 and ΔCOPD assessment test [CAT], r = -0.324; all p < 0.001). Group stratification by bone adjusted muscle volume changes revealed that groups with substantial muscle gain experienced a greater clinical benefit in pulmonary function improvements, QoL and physical performance (ΔFEV1%, 5.5 vs. 39.5; ΔIVC%, 4.3 vs. 28.4; Δ6MWDm, 14 vs. 110; ΔCATpts, -2 vs. -3.5 for groups with ΔMuscle, BAR% < -10 vs. > 10, respectively). BCA results among patients divided by the minimal clinically important difference for forced expiratory volume of the first second (FEV1) showed significant differences in bone-adjusted muscle and intramuscular adipose tissue (IMAT) volumes and their respective changes after 6 months (ΔMuscle, BAR% -5 vs. 3.4 and ΔIMAT, BAR% -0.62 vs. 0.60 for groups with ΔFEV1 ≤ 100 mL vs > 100 mL). Altered body composition, especially increased muscle volume, is associated with functional improvements in BLVR-treated patients.

Mitochondrial Dysfunction in Chronic Obstructive Pulmonary Disease: Unraveling the Molecular Nexus

Chronic obstructive pulmonary disease (COPD) is a prevalent and debilitating respiratory disorder characterized by persistent airflow limitation and chronic inflammation. In recent years, the role of mitochondrial dysfunction in COPD pathogenesis has emerged as a focal point of investigation. This review endeavors to unravel the molecular nexus between mitochondrial dysfunction and COPD, delving into the intricate interplay of oxidative stress, bioenergetic impairment, mitochondrial genetics, and downstream cellular consequences. Oxidative stress, a consequence of mitochondrial dysfunction, is explored as a driving force behind inflammation, exacerbating the intricate cascade of events leading to COPD progression. Bioenergetic impairment sheds light on the systemic consequences of mitochondrial dysfunction, impacting cellular functions and contributing to the overall energy imbalance observed in COPD patients. This review navigates through the genetic landscape, elucidating the role of mitochondrial DNA mutations, variations, and haplogroups in COPD susceptibility and severity. Cellular consequences, including apoptosis, autophagy, and cellular senescence, are examined, providing insights into the intricate mechanisms by which mitochondrial dysfunction influences COPD pathology. Therapeutic implications, spanning antioxidant strategies, mitochondria-targeted compounds, and lifestyle modifications, are discussed in the context of translational research. Important future directions include identifying novel biomarkers, advancing mitochondria-targeted therapies, and embracing patient-centric approaches to redefine COPD management. This abstract provides a comprehensive overview of our review, offering a roadmap for understanding and addressing the molecular nexus between mitochondrial dysfunction and COPD, with potential implications for precision medicine and improved patient outcomes.

Unveiling the Knowledge Frontier: A Scientometric Analysis of COPD with Sarcopenia

Objective

Numerous articles and reviews addressing the intersection of Chronic Obstructive Pulmonary Disease (COPD) with sarcopenia have been documented. However, a significant gap exists in the literature concerning scientometric analysis in this field. This study aimed to concentrate on recent research and elucidate emerging research areas through the examination of COPD with sarcopenia.

Methods

Articles in the field were systematically retrieved from the Web of Science Core Collections (WoSCC) spanning from 2003 to 2022. The analysis employed scientometric and keyword analyses through specialized software, including VOSviewer, CiteSpace, and Origin.

Results

A comprehensive analysis of 758 articles and reviews in the field of COPD with sarcopenia revealed the United States as the leading contributor in terms of publications and overall influence. Maastricht University emerged as the most prolific institution, with Schols Annemie M. W. J. being identified as the most influential scholar in this field. The International Journal of Chronic Obstructive Pulmonary Disease emerged as the most prolific journal. Notably, COPD with sarcopenia exhibits frequent associations with other diseases, underscoring the complexity of the topic and emphasizing the necessity for comprehensive treatment. Mechanistic and diagnostic aspects, particularly computed tomography, are pivotal in this research field. Osteoporosis emerges as a prospective avenue for future research, encompassing both COPD and sarcopenia. Furthermore, nutrition and physical activity are integral components for managing COPD patients with sarcopenia.

Conclusion

This study delineates the distribution of fields, the knowledge structure, and the evolution of major research topics related to COPD with sarcopenia. The identification of keyword hotspots enhances the understanding of the occurrence, development, and future study trends associated with the topic.

Cigarette smoking inhibits myoblast regeneration by promoting proteasomal degradation of NPAT protein and hindering cell cycle progression

Cigarette smoking (CS) causes skeletal muscle dysfunction, leading to sarcopenia and worse prognosis of patients with diverse systemic diseases. Here, we found that CS exposure prevented C2C12 myoblasts proliferation in a dose-dependent manner. Immunoblotting assays verified that CS exposure promoted the expression of cell cycle suppressor protein p21. Furthermore, CS exposure significantly inhibited replication-dependent (RD) histone transcription and caused S phase arrest in the cell cycle during C2C12 proliferation. Mechanistically, CS deregulated the expression levels of Nuclear Protein Ataxia-Telangiectasia Locus (NPAT/p220). Notably, the proteasome inhibitor MG132 was able to reverse the expression of NPAT in myoblasts, implying that the degradation of CS-mediated NPAT is proteasome-dependent. Overexpression of NPAT also rescued the defective proliferation phenotype induced by CS in C2C12 myoblasts. Taken together, we suggest that CS exposure induces NPAT degradation in C2C12 myoblasts and impairs myogenic proliferation through NPAT associated proteasomal-dependent mechanisms. As an application of the proteasome inhibitor MG132 or overexpression of NPAT could reverse the impaired proliferation of myoblasts induced by CS, the recovery of myoblast proliferation may be potential strategies to treat CS-related skeletal muscle dysfunction.

Real-world walking cadence in people with COPD

Introduction

The clinical validity of real-world walking cadence in people with COPD is unsettled. Our objective was to assess the levels, variability and association with clinically relevant COPD characteristics and outcomes of real-world walking cadence.

Methods

We assessed walking cadence (steps per minute during walking bouts longer than 10 s) from 7 days' accelerometer data in 593 individuals with COPD from five European countries, and clinical and functional characteristics from validated questionnaires and standardised tests. Severe exacerbations during a 12-month follow-up were recorded from patient reports and medical registries.

Results

Participants were mostly male (80%) and had mean±sd age of 68±8 years, post-bronchodilator forced expiratory volume in 1 s (FEV1) of 57±19% predicted and walked 6880±3926 steps·day-1. Mean walking cadence was 88±9 steps·min-1, followed a normal distribution and was highly stable within-person (intraclass correlation coefficient 0.92, 95% CI 0.90-0.93). After adjusting for age, sex, height and number of walking bouts in fractional polynomial or linear regressions, walking cadence was positively associated with FEV1, 6-min walk distance, physical activity (steps·day-1, time in moderate-to-vigorous physical activity, vector magnitude units, walking time, intensity during locomotion), physical activity experience and health-related quality of life and negatively associated with breathlessness and depression (all p<0.05). These associations remained after further adjustment for daily steps. In negative binomial regression adjusted for multiple confounders, walking cadence related to lower number of severe exacerbations during follow-up (incidence rate ratio 0.94 per step·min-1, 95% CI 0.91-0.99, p=0.009).

Conclusions

Higher real-world walking cadence is associated with better COPD status and lower severe exacerbations risk, which makes it attractive as a future prognostic marker and clinical outcome.

Aquatic high-intensity interval training (HIIT) may be similarly effective to land-based HIIT in improving exercise capacity in people with chronic conditions: a systematic review and meta-analysis

Objective

To investigate the effect of aquatic high-intensity interval training (AHIIT) on exercise capacity in people with chronic conditions.

Design

Systematic review and meta-analysis.

Participants

Adults (age ≥18 years) with any chronic conditions (long duration, continuing health problems).

Data sources

The databases Medline, EMBASE, CINAHL, SPORTSDiscus, PEDro and The Cochrane Library were searched from inception to 11 August 2023.

Eligibility criteria

Randomised or non-randomised controlled trials of adults reporting one or more chronic conditions were included, comparing the effect of AHIIT with a non-exercising control group, land-based high-intensity interval training (LBHIIT) or aquatic moderate-intensity continuous training (AMICT).

Results

Eighteen trials with 868 participants with chronic musculoskeletal, respiratory, cardiovascular, metabolic or neurological conditions were included. Adherence to AHIIT was high, ranging from 84% to 100%. There was moderate certainty in evidence according to the Grading of Recommendations Assessment, Development and Evaluation system for a moderate beneficial effect on exercise capacity standardised mean differences (SMD) 0.78 (95% CI 0.48 to 1.08), p<0.00001) of AHIIT compared with a non-exercising control group. There was moderate certainty in evidence for no difference of effects on exercise capacity (SMD 0.28 (95% CI -0.04 to 0.60), p=0.08) of AHIIT compared with LBHIIT. There was moderate certainty in evidence for small effect on exercise capacity (SMD 0.45 (95% CI 0.10 to 0.80), p=0.01) of AHIIT compared with AMICT.

Conclusion

There are beneficial effects of AHIIT on exercise capacity in people with a range of chronic conditions. AHIIT has similar effects on exercise capacity as LBHIIT and may represent an alternative for people unable to perform LBHIIT.

PROSPERO registration number

CRD42022289001.

Comparison of high-intensity interval training versus moderate-intensity continuous training in pulmonary rehabilitation for interstitial lung disease: a randomised controlled pilot feasibility trial

OBJECTIVES

This study aimed to investigate the feasibility and efficacy of high-intensity interval training (HIIT) compared with moderate-intensity continuous training (MICT) in pulmonary rehabilitation (PR) for people with interstitial lung disease (ILD).

DESIGN

Single-centre, randomised controlled feasibility, pilot trial.

SETTING

Patients were recruited from the chest clinic of a tertiary ILD centre and attended circuit-based PR in the hospital's gym, followed by a personalised 6-month community programme.

PARTICIPANTS

58 patients, stratified per ILD type, were randomised into two groups: 33 to HIIT (18 males:15 females) (mean age (SD): 70.2 (11.4) years) and 25 to the MICT exercise mode (14 males:11 females) (mean age (SD): 69.8 (10.8) years).

INTERVENTIONS

8-week, twice weekly, circuit-based PR programme of exercise and education, followed by a personalised 6-month community exercise programme.

OUTCOME MEASURES

Feasibility outcomes included staff-to-patient ratio and dropout rates per group. Primary outcome was the 6 min walk distance (6MWD). Secondary outcomes included the sniff nasal pressure, mouth inspiratory and expiratory pressures, handgrip and quadriceps strength and health status. Random-effects models were used to evaluate average variation in outcomes through time across the two groups.

RESULTS

The 6MWD peaked earlier with HIIT compared with MICT (at 4 months vs 5 months) but values were lower at peak (mean (95% CI): 26.3 m (3.5 to 49.1) vs 51.6 m (29.2 to 73.9)) and declined faster at 6 months post-PR. Secondary outcomes showed similar faster but smaller improvements with HIIT over MICT and more consistent maintenance 6 months post-PR with MICT than HIIT.

CONCLUSIONS

HIIT is feasible in circuit-based ILD PR programmes and provides quick improvements but requires closer supervision of training and resources than MICT and benefits may be less well sustained. This would make it a less attractive option for clinical PR programmes. A definitive, multicentre randomised controlled trial is required to address the role of HIIT in ILD.

TRIAL REGISTRATION NUMBER

ISRCTN55846300.

[Pulmonary Rehabilitation]

Reduced exercise capacity, skeletal muscle dysfunction, and a physically inactive lifestyle are linked with symptoms of fatigue and dyspnea in people suffering from chronic lung disease. Numerous such extrapulmonary manifestations have been identified as treatable aspects of pulmonary rehabilitation (PR). PR is an extensive personalized non-pharmaceutical intervention, encompassing, but not limited to, exercise training, respiratory therapy, and education. The content and goals of a PR-program are based on a comprehensive patient assessment at the time of rehabilitation admission, with personalized therapies provided by a multidisciplinary team of healthcare professionals. This article provides an overview of PR including possible indications, therapy contents (e. g. exercise training, respiratory therapy), and evidence (COPD, interstitial lung disease, COVID-19). Finally, options for pulmonary rehabilitation maintenance services in Germany are presented.

Reference equations for quadriceps strength, endurance and power: a multicentre study

Introduction

The lack of reference values of lower-limb muscle function hinders the clinical recommendations of its measurement in patients with COPD. Therefore, this study aimed to develop reference equations to predict reference values for quadriceps strength, endurance and power and evaluate their construct validity in patients with COPD.

Methods

Quadriceps strength, endurance and power were assessed in 158 healthy individuals and 87 patients with COPD. In addition, patients with COPD performed a 6-min walk test (6MWT) and a 1-min sit-to-stand test (1STS). Multiple linear regressions were performed to develop reference equations. The proportion of patients with COPD with reduced quadriceps function was determined, and correlations between quadriceps strength, endurance and power expressed in percentage of predicted values and 6MWT and 1STS performance were used to document the construct validity of the reference equation.

Results

Except for quadriceps isometric endurance, the proposed reference equations explained 50-70% of the variance of the quadriceps properties in healthy individuals. All quadriceps properties were systematically reduced in a large proportion of patients with COPD compared to healthy individuals. Correlation coefficients between quadriceps properties expressed in percentage of predicted values and 6MWT and 1STS performance ranged between 0.28 and 0.49 (all p<0.05).

Conclusion

In healthy individuals, age, sex, height and body mass index explained 50-70% of the variance of quadriceps strength, endurance and power. When expressed in percentage of predicted values, these quadriceps properties correlated with 6MWT and 1STS performance, suggesting construct validity of the reference values in patients with COPD.

High Prevalence of Non-Responders Based on Quadriceps Force after Pulmonary Rehabilitation in COPD

Pulmonary rehabilitation (PR) in patients with COPD improves quality of life, dyspnea, and exercise tolerance. However, 30 to 50% of patients are "non-responders" (NRs) according to considered variables. Surprisingly, peripheral muscle force is never taken into account to attest the efficacy of PR, despite its major importance. Thus, we aimed to estimate the prevalence of force in NRs, their characteristics, and predictors of non-response. In total, 62 COPD patients were included in this retrospective study (May 2019 to December 2020). They underwent inpatient PR, and their quadriceps isometric maximal force (Q_MVC) was assessed. The PR program followed international guidelines. Patients with a Q_MVC increase <7.5 N·m were classified as an NR. COPD patients showed a mean improvement in Q_MVC after PR (10.08 ± 12.97 N·m; p < 0.001). However, 50% of patients were NRs. NRs had lower pre-PR values for body mass, height, body mass index, PaO₂, and Q_MVC. Non-response can be predicted by low Q_MVC, high PaCO₂, and gender (when male). This model has a sensitivity of 74% and specificity of 81%. The study highlights the considerable number of NRs and potential risk factors for non-response. To systematize the effects, it may be interesting to implement blood gas correction and/or optimize the programs to enhance peripheral and central effects.

An alternative mechanism for skeletal muscle dysfunction in long-term post-viral lung disease

Chronic lung disease is often accompanied by disabling extrapulmonary symptoms, notably skeletal muscle dysfunction and atrophy. Moreover, the severity of respiratory symptoms correlates with decreased muscle mass and in turn lowered physical activity and survival rates. Previous models of muscle atrophy in chronic lung disease often modeled chronic obstructive pulmonary disease (COPD) and relied on cigarette smoke exposure and LPS stimulation, but these conditions independently affect skeletal muscle even without accompanying lung disease. Moreover, there is an emerging and pressing need to understand the extrapulmonary manifestations of long-term post-viral lung disease (PVLD) as found in COVID-19. Here, we examine the development of skeletal muscle dysfunction in the setting of chronic pulmonary disease caused by infection due to the natural pathogen Sendai virus using a mouse model of PVLD. We identify a significant decrease in myofiber size when PVLD is maximal at 49 days after infection. We find no change in the relative types of myofibers, but the greatest decrease in fiber size is localized to fast-twitch-type IIB myofibers based on myosin heavy chain immunostaining. Remarkably, all biomarkers of myocyte protein synthesis and degradation (total RNA, ribosomal abundance, and ubiquitin-proteasome expression) were stable throughout the acute infectious illness and chronic post-viral disease process. Together, the results demonstrate a distinct pattern of skeletal muscle dysfunction in a mouse model of long-term PVLD. The findings thereby provide new insights into prolonged limitations in exercise capacity in patients with chronic lung disease after viral infections and perhaps other types of lung injury.NEW & NOTEWORTHY Our study used a mouse model of post-viral lung disease to study the impact of chronic lung disease on skeletal muscle. The model reveals a decrease in myofiber size that is selective for specific types of myofibers and an alternative mechanism for muscle atrophy that might be independent of the usual markers of protein synthesis and degradation. The findings provide a basis for new therapeutic strategies to correct skeletal muscle dysfunction in chronic respiratory disease.

Delayed cortical bone healing due to impaired nuclear Nrf2 translocation in COPD mice

The effect of the pathogenesis of chronic obstructive pulmonary disease (COPD) on bone fracture healing is unknown. Oxidative stress has been implicated in the systemic complications of COPD, and decreased activity of Nrf2 signaling, a central component of the in vivo antioxidant mechanism, has been reported. We investigated the process of cortical bone repair in a mouse model of elastase-induced emphysema by creating a drill hole and focusing on Nrf2 and found that the amount of new bone in the drill hole was reduced and bone formation capacity was decreased in the model mice. Furthermore, nuclear Nrf2 expression in osteoblasts was reduced in model mice. Sulforaphane, an Nrf2 activator, improved delayed cortical bone healing in model mice. This study indicates that bone healing is delayed in COPD mice and that impaired nuclear translocation of Nrf2 is involved in delayed cortical bone healing, suggesting that Nrf2 may be a novel target for bone fracture treatment in COPD patients.

Microalgae Produce Antioxidant Molecules with Potential Preventive Effects on Mitochondrial Functions and Skeletal Muscular Oxidative Stress

In recent years, microalgae have become a source of molecules for a healthy life. Their composition of carbohydrates, peptides, lipids, vitamins and carotenoids makes them a promising new source of antioxidant molecules. Skeletal muscle is a tissue that requires constant remodeling via protein turnover, and its regular functioning consumes energy in the form of adenosine triphosphate (ATP), which is produced by mitochondria. Under conditions of traumatic exercise or muscular diseases, a high production of reactive oxygen species (ROS) at the origin of oxidative stress (OS) will lead to inflammation and muscle atrophy, with life-long consequences. In this review, we describe the potential antioxidant effects of microalgae and their biomolecules on mitochondrial functions and skeletal muscular oxidative stress during exercises or in musculoskeletal diseases, as in sarcopenia, chronic obstructive pulmonary disease (COPD) and Duchenne muscular dystrophy (DMD), through the increase in and regulation of antioxidant pathways and protein synthesis.

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.

Nitrosative and Oxidative Stress, Reduced Antioxidant Capacity, and Fiber Type Switch in Iron-Deficient COPD Patients: Analysis of Muscle and Systemic Compartments

We hypothesized that a rise in the levels of oxidative/nitrosative stress markers and a decline in antioxidants might take place in systemic and muscle compartments of chronic obstructive pulmonary disease (COPD) patients with non-anemic iron deficiency. In COPD patients with/without iron depletion (n = 20/group), markers of oxidative/nitrosative stress and antioxidants were determined in blood and vastus lateralis (biopsies, muscle fiber phenotype). Iron metabolism, exercise, and limb muscle strength were assessed in all patients. In iron-deficient COPD compared to non-iron deficient patients, oxidative (lipofuscin) and nitrosative stress levels were greater in muscle and blood compartments and proportions of fast-twitch fibers, whereas levels of mitochondrial superoxide dismutase (SOD) and Trolox equivalent antioxidant capacity (TEAC) decreased. In severe COPD, nitrosative stress and reduced antioxidant capacity were demonstrated in vastus lateralis and systemic compartments of iron-deficient patients. The slow- to fast-twitch muscle fiber switch towards a less resistant phenotype was significantly more prominent in muscles of these patients. Iron deficiency is associated with a specific pattern of nitrosative and oxidative stress and reduced antioxidant capacity in severe COPD irrespective of quadriceps muscle function. In clinical settings, parameters of iron metabolism and content should be routinely quantify given its implications in redox balance and exercise tolerance.

Selective androgen receptor modulation for muscle weakness in chronic obstructive pulmonary disease: a randomised control trial

BACKGROUND

Selective androgen receptor modulators (SARMs) increase muscle mass via the androgen receptor. This phase 2A trial investigated the effects of a SARM, GSK2881078, in conjunction with exercise, on leg strength in patients with chronic obstructive pulmonary disease (COPD) and impaired physical function.

METHODS

47 postmenopausal women and 50 men with COPD (forced expiratory volume in 1 s 30%-65% predicted; short physical performance battery score: 3-11) were enrolled into a randomised double-blind, placebo control trial. Patients were randomised 1:1 to once daily placebo or oral GSK2881078 (females: 1.0 mg; males: 2.0 mg) for 13 weeks with a concurrent home-exercise programme, involving strength training and physical activity. Primary endpoints were change from baseline in leg strength at 90 days (one-repetition maximum; absolute (kg) and relative (% change)) and multiple safety outcomes. Secondary endpoints included lean body mass, physical function and patient-reported outcomes.

RESULTS

GSK2881078 increased leg strength in men. The difference in adjusted mean change from baseline and adjusted mean percentage change from baseline between treatment and placebo were: for women, 8.0 kg (90% CI -2.5 to 18.4) and 5.2% (90% CI -4.7 to 15.0), respectively; for men, 11.8 kg (90% CI -0.5 to 24.0) and 7.0% (90% CI 0.5 to 13.6), respectively. Lean body mass increased, but no changes in patient-reported outcomes were observed. Reversible reductions in high-density lipoprotein-cholesterol and transient elevations in hepatic transaminases were the main treatment-related safety findings.

CONCLUSIONS

GSK2881078 was well tolerated and short-term treatment increased leg strength, when expressed as per cent predicted, in men with COPD more than physical training alone.

TRIAL REGISTRATION NUMBER

NCT03359473.

Muscle Power in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-analysis

This study aimed to review the impact of training on muscle power in patients with chronic obstructive pulmonary disease (COPD). Randomized controlled trials evaluating the effects of exercise-based interventions on limbs muscle power and rate of force development in COPD patients were investigated. Five international databases were searched until October 2022. Meta-analyses were performed calculating the mean difference or standardized mean difference. Risk of bias in studies was assessed using Cochrane Risk of Bias tool 2.0. A total of nine studies were included in the analysis. There were concerns about risk of bias in seven out of nine studies. Comparison of exercising and non-exercising groups showed a significant effect of exercise in improving muscle power (P=0.0004) and rate of force development (P<0.001), in five and three trials, respectively. Four studies comparing different trainings showed no significant results on muscle power (P=0.45). Eight to 16 weeks of exercise-based intervention versus no intervention might be beneficial to enhance upper and lower limbs muscle power and rate of force development in people with COPD. In contrast, muscle power did not improve when different training modalities were compared. Future studies performing power training in COPD patients are encouraged.

Associations Between Muscle Weakness and Clinical Outcomes in Current and Former Smokers

Introduction

Smokers with chronic obstructive pulmonary disease (COPD) are at increased risk of muscle weakness. There are limited data describing weakness in smokers with normal spirometry and preserved ratio-impaired spirometry (PRISm), 2 subgroups at risk of respiratory symptom burden and activity limitations. In this study, we evaluated the associations of 2 weakness measures, sit-to-stand (STS) and handgrip strength (HGS), with clinical outcomes in smokers with COPD, normal spirometry, and PRISm.

Methods

We evaluated 1972 current and former smokers from the COPD Genetic Epidemiology (COPDGene®) cohort with STS and HGS measurements at their 10-year study visit. Multivariable regression modeling was used to assess associations between weakness measures and the 6-minute walk distance (6MWD) test, the St George's Respiratory Questionnaire (SGRQ), the Short-Form-36 (SF-36), severe exacerbations, and prospective mortality, reported as standardized coefficients (β), odds ratios (ORs), or hazard ratios (HRs).

Results

Compared with HGS, STS was more strongly associated with the 6MWD (β=0.45, p<0.001 versus. β=0.25, p<0.001), SGRQ (β=-0.24, p<0.001 versus β=-0.18, p<0.001), SF-36 Physical Functioning (β=0.36, p<0.001 versus β=0.25, p<0.001), severe exacerbations (OR 0.95, p=0.04 versus OR 0.97, p=0.01), and prospective mortality (HR 0.83, p=0.001 versus HR 0.94, p=0.03). Correlations remained after stratification by spirometric subgroups. Compared with males, females had larger magnitude effect sizes between STS and clinical outcomes.

Conclusions

STS and HGS are easy to perform weakness measures that provide important information about functional performance, health-related quality of life, severe exacerbations, and survival in smokers, regardless of spirometric subgroup. This iterates the importance of screening current and former smokers for weakness in the outpatient setting.

Role of Nrf2 and exercise in alleviating COPD-induced skeletal muscle dysfunction

Chronic obstructive pulmonary disease (COPD) is a complex chronic respiratory disease with cumulative impacts on multiple systems, exhibiting significant extrapulmonary impacts, and posing a serious public health problem. Skeletal muscle dysfunction is one of the most pronounced extrapulmonary effects in patients with COPD, which severely affects patient prognosis and mortality primarily through reduced productivity resulting from muscle structural and functional alterations. Although the detailed pathogenesis of COPD has not been fully determined, some researchers agree that oxidative stress plays a significant role. Oxidative stress not only catalyzes the progression of pulmonary symptoms but also drives the development of skeletal muscle dysfunction. Nuclear factor erythroid 2-related factor 2 (Nrf2), is a key transcription factor that regulates the antioxidant response and plays an enormous role in combating oxidative stress. In this review, we have summarized current research on oxidative stress damage to COPD skeletal muscle and analyzed the role of Nrf2 in improving skeletal muscle dysfunction in COPD through exercise. The results suggest that oxidative stress drives the occurrence and development of skeletal muscle dysfunction in COPD. Exercise may improve skeletal muscle dysfunction in patients with COPD by promoting the dissociation of Kelch-like ECH-associated protein 1 (Keap1) and Nrf2, inducing sequestosome1(p62) phosphorylation to bind with Keap1 competitively leading to Nrf2 stabilization and improving dynamin-related protein 1-dependent mitochondrial fission. Nrf2 may be a key target for exercise anti-oxidative stress to alleviate skeletal muscle dysfunction in COPD.

Effect on muscle strength after blood flow restriction resistance exercise in early in-patient rehabilitation of post-chronic obstructive pulmonary disease acute exacerbation, a single blinded, randomized controlled study

BACKGROUND

Early commencement of rehabilitation might counteract the loss of muscle strength due to a chronic obstructive pulmonary disease acute exacerbation (COPDAE). Blood flow restriction resistance exercise (BFR-RE) using a low intensity of training load has demonstrated muscle strength gain in varieties of clinical populations. This trial aimed at studying the efficacy and acceptability of BFR-RE in patients with post-COPDAE which was not reported before.

METHOD

A prospective, assessor blinded, randomized controlled study with 2-week in-patient rehabilitation program with BFR-RE was compared to a matched program with resistance exercise without BFR in patients with post-COPDAE. The primary outcome was the change of muscle strength of knee extensor of dominant leg. The secondary outcomes included changes of hand grip strength (HGS), 6-minute walk test (6MWT) distance, short physical performance battery (SPPB) scores, COPD assessment test (CAT) scores; acceptability and feasibility of BFR-RE; and 1-month unplanned re-admission rate.

RESULTS

Forty-Five post-COPDAE patients (mean age = 76 ± 10, mean FEV1%=49% ± 24%) were analyzed. After training, BFR-RE group and control group demonstrated a statistically significant median muscle strength gain of 20 (Interquartile range (IQR) 3 to 38) Newton(N) and 12 (IQR -9 to 30) N respectively. BFR-RE group showed a significant change in SPPB scores, but not in 6MWT distance and HGS after training. Between groups did not have statistically significant different in all primary and secondary outcomes, though with similar acceptability. Drop-out rate due to training-related discomfort in BFR-RE group was 3.7%.

CONCLUSION

BFR-RE is feasible and acceptable in patients with post-COPDAE. A 2-week inpatient pulmonary rehabilitation with BFR-RE improved muscle strength of knee extensors, but not a greater extent than the same rehabilitation program with resistance exercise without BFR. Further studies could be considered with a longer training duration and progression of resistance load. [ClinicalTrials.gov Identifier: NCT04448236].

Determinants of acute care discharge in adults with chronic obstructive pulmonary disease

CONCLUSIONS

In adults with COPD basic mobility scores on the AM-PAC "6-clicks" measure completed at discharge had the best sensitivity and specificity for predicting discharge to home and need for rehab services.

Obstructive sleep apnea reduces functional capacity and impairs cardiac autonomic modulation during submaximal exercise in patients with chronic obstructive pulmonary disease: A follow-up study

BACKGROUND

Functional capacity and heart rate variability (HRV) are important prognostic markers in chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea syndrome (OSA). However, the impact of the overlap of these diseases and the one-year clinical follow-up has not yet been evaluated.

OBJECTIVES

To assess whether the presence of OSA can impair functional performance and cardiac autonomic control during exercise in patients with COPD; and to verify whether the overlap of these diseases could lead to worse clinical outcomes during the one-year follow-up.

METHODS

Thirty-four patients underwent pulmonary function tests, echocardiography and polysomnography for diagnostic confirmation, disease staging, exclusion of any cardiac changes, and allocation between groups. The patients underwent the six-minute walk test (6MWT) to assess functional capacity and HRV during exercise. Subsequently, patients were followed up for 12 months to record outcomes such as exacerbation, hospitalization, and deaths. At the end of this period, the patients were revaluated to verify the hypotheses of the study.

RESULTS

The OSA-COPD group showed greater functional impairment when compared to the COPD group (p=0.003) and showed worse cardiac autonomic responses during the 6MWT with greater parasympathetic activation (p=0.03) and less complexity of the autonomic nervous system, in addition to being more likely to exacerbate (p=0.03) during one year of follow-up.

CONCLUSION

OSA-COPD produces deleterious effects on functional performance and a greater autonomic imbalance that impairs clinical outcomes.

Effectiveness of a Long-term Home-Based Exercise Training Program in Patients With COPD After Pulmonary Rehabilitation: A Multicenter Randomized Controlled Trial

BACKGROUND

Most patients with COPD do not maintain exercise training after pulmonary rehabilitation (PR).

RESEARCH QUESTION

Does a 12-month home-based, minimal-equipment strength training program after PR have an effect on dyspnea, exercise capacity, and patient-reported outcomes in patients with COPD?

STUDY DESIGN AND METHODS

In a parallel-arm multicenter study across four Swiss PR clinics, patients with COPD were allocated randomly (1:1 ratio) into an intervention group (IG; home-based strength training program) or control group (CG; usual care). The primary outcome was change in Chronic Respiratory Questionnaire (CRQ) dyspnea scale score from baseline to 12 months. Secondary outcomes were change in exercise capacity (1-min sit-to-stand-test [1MSTST], 6-min walk test [6MWT]), health-related quality of life, exacerbations, and symptoms. We assessed the IG's experience by interviews at study end. Main analyses were based on the intention-to-treat approach, and adjusted linear regression models were used.

RESULTS

One hundred twenty-three patients with COPD (IG, n = 61; CG, n = 62) were randomized, 61 of whom were women and whose mean ± SD age was 66.8 ± 8.1 years and mean ± SD FEV₁ was 39.3 ± 15.3% predicted. One hundred four participants completed 12 months of follow-up (IG, n= 53; CG, n= 51). Of the 53 IG participants, 37 participants (70%) conducted the training until study end. We found no difference in change in CRQ dyspnea scale score over 12 months (adjusted mean difference, 0.28; 95% CI, -0.23 to 0.80; P = .27). We found moderate evidence for a difference in 1MSTST repetitions favoring the IG (adjusted mean difference, 2.6; 95% CI, 0.22-5.03; P = .033), but no evidence for an effect in other outcomes. Seventy-nine percent of the IG reported positive effects that they attributed to the training.

INTERPRETATION

The home exercise program had no effect on dyspnea, but improved 1MSTST performance and patient-perceived fitness. The supported program was well accepted by patients with COPD and may facilitate continued exercise training at home.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03461887; URL: www.

CLINICALTRIALS

gov.

Oxidative stress causes muscle structural alterations via p38 MAPK signaling in COPD mouse model

INTRODUCTION

Sarcopenia is a complication of Chronic Obstructive Pulmonary Disease (COPD) that negatively affects physical activity and quality of life. However, the underlying mechanism by which COPD affects skeletal muscles remains to be elucidated. Therefore, we investigated the association between oxidative stress and structural alterations in muscles in elastase-induced emphysema mouse models.

MATERIALS AND METHODS

Twelve-week-old male C57BL/6J mice were treated with either intratracheal porcine pancreatic elastase (PPE) dissolved in saline, or saline alone. The mice were euthanized 12 weeks after treatment, and the lungs and limb muscles were used for protein analysis of oxidative stress, p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway and muscle atrophy signaling pathway related with oxidative stress. Furthermore, C57BL/6J mice treated with PPE or saline were analyzed for the effects of oral administration of astaxanthin or p38 inhibitor.

RESULTS

The weight of the soleus muscle, proportion of type I muscle fibers, and cross-sectional areas of muscle fibers in the PPE group were lower than those in the control group. Oxidative stress marker levels in the PPE group were elevated in skeletal muscles. The p38 MAPK signaling pathway was activated in the soleus muscles, leading to the activation of the ubiquitin-proteasome system and autophagy. Astaxanthin and p38 inhibitors attenuated alterations in muscle structure through the deactivation of the p38 MAPK signaling pathway.

CONCLUSIONS

This study provides first evidence in COPD mouse model that oxidative stress trigger a series of muscle structural changes. Our findings suggest a novel target for sarcopenia in COPD.

The role of muscle-specific MicroRNAs in patients with chronic obstructive pulmonary disease and skeletal muscle dysfunction

Skeletal muscle dysfunction is a systematic manifestation of chronic obstructive pulmonary disease (COPD), which is manifested through the changes in the respiratory and peripheral muscle fiber types, reducing muscle strength and endurance, and muscle atrophy. Muscle dysfunction limits the daily mobility, negatively affects the quality of life, and may increase the patient’s risk of mortality. MicroRNAs (miRNAs) as the regulators of gene expression, plays an important role in modulating skeletal muscle dysfunction in COPD by regulating skeletal muscle development (proliferation, differentiation), protein synthesis and degradation, inflammatory response, and metabolism. In particular, muscle-specific miRNAs (myomiRs) may play an important role in this process, although the different expression levels of myomiRs in COPD and skeletal muscle dysfunction and the mechanisms underlying their role remain unclear. In this paper, we review the differential expression of the myomiRs in COPD to identify myomiRs that play a role in skeletal muscle dysfunction in COPD. We further explore their possible mechanisms and action in order to provide new ideas for the prevention and treatment of the skeletal muscle dysfunction in COPD.

Updated Perspectives on the Role of Biomechanics in COPD: Considerations for the Clinician

Patients with chronic obstructive pulmonary disease (COPD) demonstrate extra-pulmonary functional decline such as an increased prevalence of falls. Biomechanics offers insight into functional decline by examining mechanics of abnormal movement patterns. This review discusses biomechanics of functional outcomes, muscle mechanics, and breathing mechanics in patients with COPD as well as future directions and clinical perspectives. Patients with COPD demonstrate changes in their postural sway during quiet standing compared to controls, and these deficits are exacerbated when sensory information (eg, eyes closed) is manipulated. If standing balance is disrupted with a perturbation, patients with COPD are slower to return to baseline and their muscle activity is differential from controls. When walking, patients with COPD appear to adopt a gait pattern that may increase stability (eg, shorter and wider steps, decreased gait speed) in addition to altered gait variability. Biomechanical muscle mechanics (ie, tension, extensibility, elasticity, and irritability) alterations with COPD are not well documented, with relatively few articles investigating these properties. On the other hand, dyssynchronous motion of the abdomen and rib cage while breathing is well documented in patients with COPD. Newer biomechanical technologies have allowed for estimation of regional, compartmental, lung volumes during activity such as exercise, as well as respiratory muscle activation during breathing. Future directions of biomechanical analyses in COPD are trending toward wearable sensors, big data, and cloud computing. Each of these offers unique opportunities as well as challenges. Advanced analytics of sensor data can offer insight into the health of a system by quantifying complexity or fluctuations in patterns of movement, as healthy systems demonstrate flexibility and are thus adaptable to changing conditions. Biomechanics may offer clinical utility in prediction of 30-day readmissions, identifying disease severity, and patient monitoring. Biomechanics is complementary to other assessments, capturing what patients do, as well as their capability.

An alternative mechanism for skeletal muscle dysfunction in long-term post-viral lung disease

Chronic lung disease is often accompanied by disabling extrapulmonary symptoms, notably skeletal muscle dysfunction and atrophy. Moreover, the severity of respiratory symptoms correlates with decreased muscle mass and in turn lowered physical activity and survival rates. Previous models of muscle atrophy in chronic lung disease often modeled COPD and relied on cigarette smoke exposure and LPS-stimulation, but these conditions independently affect skeletal muscle even without accompanying lung disease. Moreover, there is an emerging and pressing need to understand the extrapulmonary manifestations of long-term post-viral lung disease (PVLD) as found in Covid-19. Here, we examine the development of skeletal muscle dysfunction in the setting of chronic pulmonary disease using a mouse model of PVLD caused by infection due to the natural pathogen Sendai virus. We identify a significant decrease in myofiber size when PVLD is maximal at 49 d after infection. We find no change in the relative types of myofibers, but the greatest decrease in fiber size is localized to fast-twitch type IIB myofibers based on myosin heavy chain immunostaining. Remarkably, all biomarkers of myocyte protein synthesis and degradation (total RNA, ribosomal abundance, and ubiquitin-proteasome expression) were stable throughout the acute infectious illness and chronic post-viral disease process. Together, the results demonstrate a distinct pattern of skeletal muscle dysfunction in a mouse model of long-term PVLD. The findings thereby provide new insight into prolonged limitations in exercise capacity in patients with chronic lung disease after viral infections and perhaps other types of lung injury.

Efficacy of 12 weeks oral beta-alanine supplementation in patients with chronic obstructive pulmonary disease: a double-blind, randomized, placebo-controlled trial

BACKGROUND

Beta-alanine (BA) supplementation increases muscle carnosine, an abundant endogenous antioxidant and pH buffer in skeletal muscle. Carnosine loading promotes exercise capacity in healthy older adults. As patients with chronic obstructive pulmonary disease (COPD) suffer from elevated exercise-induced muscle oxidative/carbonyl stress and acidosis, and from reduced muscle carnosine stores, it was investigated whether BA supplementation augments muscle carnosine and induces beneficial changes in exercise capacity, quadriceps function, and muscle oxidative/carbonyl stress in patients with COPD.

METHODS

In this double-blind, randomized, placebo (PL)-controlled trial (clinicaltrials.gov identifier: NCT02770417), 40 patients (75% male) with COPD (mean ± standard deviation: age 65 ± 6 years; FEV₁ % predicted 55 ± 14%) were assigned to 12 weeks oral BA or PL supplementation (3.2 g/day). The primary outcome, i.e. muscle carnosine, was quantified from m. vastus lateralis biopsies obtained before and after intervention. Co-primary outcomes, i.e. incremental and constant work rate cycle capacity, were also assessed. Linear mixed model analyses were performed. Compliance with and side effects of supplement intake and secondary outcomes (quadriceps strength and endurance, and muscle oxidative/carbonyl stress) were also assessed.

RESULTS

Beta-alanine supplementation increased muscle carnosine in comparison with PL in patients with COPD (mean difference [95% confidence interval]; +2.82 [1.49-4.14] mmol/kg wet weight; P < 0.001). Maximal incremental cycling capacity (VO₂ peak: +0.5 [-0.7 to 1.7] mL/kg/min; P = 0.384, Wpeak: +5 [-1 to 11] W; P = 0.103) and time to exhaustion on the constant work rate cycle test (+28 [-179 to 236] s; P = 0.782) did not change significantly. Compliance with supplement intake was similar in BA (median (quartile 1-quartile 3); 100 (98-100)%) and PL (98 (96-100)%) (P = 0.294) groups, and patients did not report side effects possibly related to supplement intake. No change was observed in secondary outcomes.

CONCLUSIONS

Beta-alanine supplementation is efficacious in augmenting muscle carnosine (+54% from mean baseline value) without side effects in patients with COPD in comparison with PL. However, accompanied beneficial changes in exercise capacity, quadriceps function, and muscle oxidative/carbonyl stress were not observed.

Muscle function and functional performance after pulmonary rehabilitation in patients with chronic obstructive pulmonary disease: a prospective observational study

This study aimed to measure changes in different properties of skeletal muscles and evaluate their contribution and relationship to changes in functional performance after pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). COPD outpatients attending 5 weeks of conventional PR were recruited. Functional performance [5-repetitions sit-to-stand (5STS), and 4-m gait speed (4mGS)], and muscle function (maximal isometric strength, power, force control, and relative concentric and eccentric activation during 5STS) were assessed after PR and 3 months of follow-up. Twenty patients (71 years; 52% of predicted FEV₁) completed the study. 4mGS and relative concentric activation during 5STS decreased respectively by 7.7% and 26% between the beginning of PR and follow-up. Quadriceps strength, power, and force control improved by 10.4%, 27.3%, and 15.2%, respectively, from the beginning of PR to follow-up the relative eccentric activation during 5STS explained 31% of the variance in 4mGS changes. In conclusion, functional performance appeared to decline after conventional PR, whereas several properties of skeletal muscles were maintained at follow-up in COPD outpatients. Of note, eccentric contractions might play a role in the improvement of functional performance. Therefore, future studies with interventional design should include eccentric training in PR programs during clinical COPD practice.

Resistance training prevents damage to the mitochondrial function of the skeletal muscle of rats exposed to secondary cigarette smoke

AIM

To analyze the consumption of oxygen and to quantify the mitochondrial respiratory chain proteins (OXPHOS) in the gastrocnemius muscle of rats exposed to cigarette smoke and/or RT practitioners.

MAIN METHODS

Wistar rats were divided into groups: Control (C), Smoker (S), Exercise (E) and Exercise Smoker (ES). Groups F and ES were exposed to the smoke of 4 cigarettes for 30 min, 2× a day, 5× a week, for 16 weeks. Groups E and ES performed four climbs with progressive load, 1× per day, 5× per week, for 16 weeks. The gastrocnemius muscle was collected for analysis of OXPHOS content and oxygen consumption. Groups S (vs. C) and ES (vs. C and E) showed lower body weight gain when observing the evolution curve.

KEY FINDINGS

The S rats showed a reduction in the NDUFB8 proteins of complex 1, SDHB of complex 2, MTC01 of complex 4 and ATP5A of complex 5 (ATP Synthase) compared to Group C. Additionally, S rats also showed increased consumption of O2 in Basal, Leak, Complex I and I/II combined measures compared to the other groups, suggesting that the activity of the mitochondria of these animals increased in terms of coupling and uncoupling parameters.

SIGNIFICANCE

Our data suggest that exposure to cigarette smoke for 16 weeks is capable of causing impairment of mitochondrial function with reduced expression of respiratory chain proteins in skeletal muscle. However, the RT was effective in preventing impairment of mitochondrial function in the skeletal muscle of rats exposed to secondary cigarette smoke.

Iron Depletion in Systemic and Muscle Compartments Defines a Specific Phenotype of Severe COPD in Female and Male Patients: Implications in Exercise Tolerance

We hypothesized that iron content and regulatory factors, which may be involved in exercise tolerance, are differentially expressed in systemic and muscle compartments in iron deficient severe chronic obstructive pulmonary disease (COPD) patients. In the vastus lateralis and blood of severe COPD patients with/without iron depletion, iron content and regulators, exercise capacity, and muscle function were evaluated in 40 severe COPD patients: non-iron deficiency (NID) and iron deficiency (ID) (20 patients/group). In ID compared to NID patients, exercise capacity, muscle iron and ferritin content, serum transferrin saturation, hepcidin-25, and hemojuvelin decreased, while serum transferrin and soluble transferrin receptor and muscle IRP-1 and IRP-2 increased. Among all COPD, a significant positive correlation was detected between FEV₁ and serum transferrin saturation. In ID patients, significant positive correlations were detected between serum ferritin, hepcidin, and muscle iron content and exercise tolerance and between muscle IRP-2 and serum ferritin and hepcidin levels. In ID severe COPD patients, iron content and its regulators are differentially expressed. A potential crosstalk between systemic and muscle compartments was observed in the ID patients. Lung function and exercise capacity were associated with several markers of iron metabolism regulation. Iron status should be included in the overall assessment of COPD patients given its implications in their exercise performance.