Impaired skeletal muscle endurance related to physical inactivity and altered lung function in COPD patients

Associations of Cardiorespiratory Fitness and Muscular Endurance Fitness With Pulmonary Function in Physically Active Young Adults

RATIONALE

While the beneficial effects of physical fitness on general health are well-documented, the specific relationship between different types of physical fitness, particularly cardiorespiratory fitness (CRF) and muscular endurance fitness (MEF), and lung function in physically active young adults remains less explored.

OBJECTIVE

This study investigated the relationship between CRF and MEF, and their correlation with lung function in physically active young adults.

METHODS

This cross-sectional study involved a cohort of 1227 physically active young adults without lung diseases. Lung function was assessed using FEV1, FVC, and FEV1/FVC measurements. The 3000-m run was used to assess CRF, and the 2-min push-up and sit-up tests were used to assess MEF. Multivariable linear regression analysis was used to evaluate the relationships between these fitness measures and lung function, adjusting for potential covariates.

RESULTS

Enhanced CRF was associated with superior FEV1 and FVC after adjusting for covariates (β=-.078, p=.015 for FEV1; β=-.086, p=.009 for FVC). Push-ups were positively associated with FEV1 (β=.102, p=.014), but not with FVC. In contrast, sit-ups showed no significant correlation with lung function in the fully adjusted model.

CONCLUSION

The study demonstrated a clear association between improved physical fitness and better lung function in physically active young adults, with various exercises showing distinct associations with lung metrics. Notably, push-ups were particularly associated with higher FEV1. A future prospective study is necessary to determine whether routine exercises, such as push-ups, might lead to greater lung function.

Steamed Ginseng Berry Powder Ameliorates Skeletal Muscle Atrophy via Myogenic Effects

Sarcopenia is an age-related loss of muscle mass and function for which there is no approved pharmacological treatment. We tested direct efficacy by evaluating grip strength improvement in a sarcopenia mouse model rather than drug screening, which inhibits specific molecular mechanisms. Various physiological functions of ginseng berries are beneficial to the human body. The present study aimed to evaluate the efficacy and safety of steamed ginseng berry powder (SGBP). SGBP administration increased myotube diameter and suppressed the mRNA expression of sarcopenia-inducing molecules. SGBP also reduced the levels of inflammatory transcription factors and cytokines that are known to induce sarcopenia. Oral administration of SGBP improved muscle mass and physical performance in a mouse model of sarcopenia. In summary, our data suggest that SGBP is a novel therapeutic candidate for the amelioration of muscle weakness, including sarcopenia.

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.

Effects of photobiomodulation as an adjunctive treatment in chronic obstructive pulmonary disease: a narrative review

Chronic obstructive pulmonary disease (COPD) is a disease characterized by chronic airway inflammation and remodeling and lung parenchymal inflammation and destruction, which result in many pulmonary and extrapulmonary manifestations. The anti-inflammatory effect of photobiomodulation (PBM) has been reported in previous studies. This review was conducted to evaluate the direct effect of PBM on lung inflammation in COPD. The other effects of PBM on modulation of peripheral and respiratory muscle metabolism and angiogenesis in lung tissues were also discussed. The databases of PubMed, Cochrane Library, and Google Scholar were searched to find the relevant studies. Keywords included PBM and related terms, COPD-related signs, and lung inflammation. A total of 12 articles were selected and reviewed in this study. Based on the present review, PBM is helpful in reducing lung inflammation through decreasing the inflammatory cytokines and chemokines at multiple levels and increasing anti-inflammatory cytokines. In addition, PBM also improves both peripheral and respiratory muscle metabolism and promote angiogenesis. This review demonstrated that PBM is a promising adjunctive treatment modality for COPD management which merits further validation.

Feasibility of Muscle Endurance Testing in Critically Ill Trauma Patients: A Pilot Study

Intensive care unit-acquired weakness (ICUAW) occurs secondary to patients treated for life-threatening conditions in the ICU being diagnosed based on the Medical Research Council sum score (MRC-SS). However, patients often complain of fatigability and poor endurance, which are not evaluated by muscle strength. In this study, we explored the feasibility of assessing muscle quality and endurance in trauma ICU patients. The modified Functional Index-2 (FI2) testing was applied to evaluate muscle endurance. The maximal voluntary contraction (MVC) was measured when evaluating the MRC-SS using surface electromyography (sEMG), and the fatigue index (FI) was also recorded at the time of endurance testing. The ultrasonic muscle echogenicity by gray-scale analysis of rectus femoris (RF) and tibialis anterior (TA) muscles was evaluated at the initial (<72 h) and end of ICU care. A total of 14 patients were enrolled in this study. Fatigue was induced in eight patients (fatigue group), and six (non-fatigue group) completed endurance testing. All patients except one had an MRC-SS exceeding 48 points. There was no difference in US echogenicity, MRC-SS, and FI between groups. In sEMG, the root mean square (RMS) values of MVC in RF and TA muscles showed a significant difference (p < 0.05). To evaluate and predict the functional activity of ICU patients, measuring muscle strength alone is insufficient, and it is necessary to evaluate muscle endurance. In this respect, the modified FI2 test and sEMG monitoring are considered to be promising procedures for evaluating the muscle condition of critically ill patients even in complex situations in the ICU.

The effect of a pressure ventilatory support on quadriceps endurance is maintained after exercise training in severe COPD patients. A longitudinal randomized, cross over study

Purpose: In severe chronic obstructive pulmonary disease (COPD) patients, the application of an inspiratory pressure support (IPS) during exercise increases exercise tolerance and the benefit of exercise training during pulmonary rehabilitation (PR). Moreover, it improves quadriceps endurance after a session of cycling exercise suggesting a reduced muscle fatigue. We looked for the persistence of this effect after PR and sought an association between the improved quadriceps endurance with IPS and the training load during PR.

Patients and methods: We studied 20 patients with severe COPD (6 in stage 3and 14 in stage 4 of GOLD) before and after PR. As part of a PR program, patients completed 16 cycling sessions over 6 weeks with the addition of IPS during exercise. As a surrogate of muscular fatigue, quadriceps endurance was measured at 70% of maximal strength in a control condition, after a constant work rate exercise test (CWR) with IPS (TlimQ IPS) or with a sham ventilation (TlimQsham), in a random order. These tests were repeated similarly at the end of PR.

Results: PR was associated with a significant increase in maximal power output, cycling endurance, quadriceps strength and endurance. Session training load (power output x duration of the session) increased by 142% during the course of the program. Before PR, CWR duration increases with IPS compared to sham ventilation (Δtime = +244s, p = 0.001). Compared to control condition, post-exercise TlimQ reduction was lower with IPS at isotime than at the end of CWR or than with sham ventilation (−9 ± 21%, −18 ± 16% and −23 ± 18%, respectively, p = 0.09, p &lt; 0.0001 and p &lt; 0.0001). After PR, the post-exercise decrease of TlimQ was reduced after IPS compared to sham (−9 ± 18% vs. −21 ± 17%, respectively, p = 0.004). No relationship was found between the prevention of quadriceps fatigue and the training load.

Conclusion: In severe COPD patients, the beneficial effect of a ventilator support on quadriceps endurance persisted after PR with IPS. However, it was not related to the increase in training load, and could not predict the training response to non-invasive ventilation during exercise.

Efficacy of Different Types of Physical Activity Interventions on Exercise Capacity in Patients with Chronic Obstructive Pulmonary Disease (COPD): A Network Meta-Analysis

AIM

A network meta-analysis (NMA) was performed to determine the effects on the exercise capacity, measured by the 6 MWT, of patients with COPD of (i) different physical activity interventions and (ii) supervised or unsupervised programs.

METHODS

A literature search was carried out from inception to April 2022. Randomized controlled trials of the effectiveness of physical activity on exercise capacity in patients with COPD were included. The risk of bias was assessed using the Cochrane Risk of Bias (RoB 2.0) tool, and the Grading of Recommendations, Assessment, Development, and Evaluation tool (GRADE) was used to assess the quality of the evidence. A pairwise meta-analysis for direct and indirect effects was carried out.

RESULTS

A total of 41 studies were included in this NMA. The highest effects were for urban training pulmonary rehabilitation (PR) programs (ES, 1.50; 95% CI: 0.46 and 2.55) versus the control group. For supervised and unsupervised PR and home-based PR programs, the highest effects were found for supervised PR (ES, 0.85; 95% CI: 0.46 to 1.23) versus the control group.

CONCLUSIONS

PR implemented with urban circuit training should be considered the most effective strategy to improve exercise capacity in patients with COPD. Supervision of the programs improves exercise capacity.

Nutritional Status and Body Composition in Patients Suffering From Chronic Respiratory Diseases and Its Correlation With Pulmonary Rehabilitation

As part of an individualized intervention to improve the physical, emotional, and social functioning of patients with chronic respiratory diseases in general and chronic obstructive pulmonary disease in particular, awareness of the presence and consequences of changes in body composition increased enormously during the last decades, and nutritional intervention is considered as an essential component in the comprehensive approach of these patients. This review describes the prevalence and the clinical impact of body composition changes and also provides an update of current intervention strategies. It is argued that body composition, preferentially a three-component evaluation of fat, lean, and bone mass, must become part of a thorough assessment of every patient, admitted for pulmonary rehabilitation.

Skeletal Muscle Phenotype in Patients Undergoing Long-Term Hemodialysis Awaiting Kidney Transplantation

BACKGROUND AND OBJECTIVES

Age and comorbidity-related sarcopenia represent a main cause of muscle dysfunction in patients on long-term hemodialysis. However, recent findings suggest muscle abnormalities that are not associated with sarcopenia. The aim of this study was to isolate functional and cellular muscle abnormalities independently of other major confounding factors, including malnutrition, age, comorbidity, or sedentary lifestyle, which are common in patients on maintenance hemodialysis. To overcome these confounding factors, alterations in skeletal muscle were analyzed in highly selected patients on long-term hemodialysis undergoing kidney transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In total, 22 patients on long-term hemodialysis scheduled for kidney transplantation with few comorbidities, but with a long-term uremic milieu exposure, and 22 age, sex, and physical activity level frequency-matched control participants were recruited. We compared biochemical, functional, and molecular characteristics of the skeletal muscle using maximal voluntary force and endurance of the quadriceps, 6-minute walking test, and muscle biopsy of vastus lateralis. For statistical analysis, mean comparison and multiple regression tests were used.

RESULTS

In patients on long-term hemodialysis, muscle endurance was lower, whereas maximal voluntary force was not significantly different. We observed a transition from type I (oxidative) to type II (glycolytic) muscle fibers, and an alteration of mitochondrial structure (swelling) without changes in DNA content, genome replication (peroxisome proliferator activator receptor γ coactivator-1α and mitochondrial transcription factor A), regulation of fusion (mitofusin and optic atrophy 1), or fission (dynamin-related protein 1). Notably, there were autophagosome structures containing glycogen along with mitochondrial debris, with a higher expression of light chain 3 (LC3) protein, indicating phagophore formation. This was associated with a greater conversion of LC3-I to LC3-II and the expression of Gabaralp1 and Bnip3l genes involved in mitophagy.

CONCLUSIONS

In this highly selected long-term hemodialysis population, a low oxidative phenotype could be defined by a poor endurance, a fiber-type switch, and an alteration of mitochondria structure, without evidence of sarcopenia. This phenotype could be related to uremia through the activation of autophagy/mitophagy.

CLINICAL TRIAL REGISTRATION NUMBERS

NCT02794142 and NCT02040363.

Does branched-chain amino acid supplementation improve pulmonary rehabilitation effect in COPD?

BACKGROUND

Muscle wasting is frequent in chronic obstructive lung disease (COPD) and associated with low branched-chain amino acids (BCAA). We hypothesized that BCAA supplementation could potentiate the effect of a pulmonary rehabilitation program (PRP) by inducing muscular change.

MATERIALS AND METHODS

Sixty COPD patients (GOLD 2-3) were involved in an ambulatory 4-week PRP either with BCAA oral daily supplementation or placebo daily supplementation in a randomized double-blind design. Maximal exercise test including quadriceps oxygenation measurements, functional exercise test, muscle strength, lung function tests, body composition, dyspnea and quality of life were assessed before and after PRP.

RESULTS

Fifty-four patients (64.9 ± 8.3 years) completed the protocol. In both groups, maximal exercise capacity, functional and muscle performances, quality of life and dyspnea were improved after 4-week PRP (p ≤ 0.01). Changes in muscle oxygenation during the maximal exercise and recovery period were not modified after 4-week PRP in BCAA group. Contrarily, in the placebo group the muscle oxygenation kinetic of recovery was slowed down after PRP.

CONCLUSION

This study demonstrated that a 4-week PRP with BCAA supplementation is not more beneficial than PRP alone for patients. A longer duration of supplementation or a more precise targeting of patients would need to be investigated to validate an effect on muscle recovery and to demonstrate other beneficial effects.

[Pulmonary rehabilitation, a historical perspective from Hippocrates to tele-rehabilitation]

In ancient times Hippocrates described a disease, the 3rd phthisis, which seems to correspond to COPD and is mainly treated by walking, gradually increasing the number of steps until reaching 10,000 steps a day at the end of the initial period of treatment. The recent era began in the second half of the 20th century and ended in 2015, with an unusual Cochrane Library editorial in which it was stated that the accumulated evidence (statistically significant and clinically relevant improvements in clinical signs, tolerance to exercise, quality of life, days hospitalization…) on the effects of rehabilitation programs suffice to suspend research on the subject and to justify focus on new elements in the programs. It is essential, in fact, to establish uniform practical recommendations for the prescription of routine rehabilitation (number and duration of physical activity sessions, therapeutic education, re-training intensity…). In addition, studies should be carried out on new practices: community or home rehabilitation, long-term rehabilitation, tele-rehabilitation.

The correlation between quadriceps muscle strength and endurance and exercise performance in patients with COPD

To determine the association between quadriceps muscle strength (QMS) and endurance (QME) and exercise capacity in patients with COPD after stratification for sex and resting lung function (LF). Data were collected from 3,246 patients with COPD (60% men, 64 ± 9 yr), including measures of exercise capacity [peak aerobic capacity (peakV̇o₂), 6-min walk distance (6MWD)] and isokinetic QMS and QME. Patients were stratified for sex, forced expiratory volume in 1 s (>50/≤50% predicted), single breath carbon monoxide diffusing capacity (>50/≤50% predicted), and residual volume (>140/≤140% predicted). After stratification for resting LF, QMS and QME were significantly associated with peakV̇o₂ (r range: 0.47-0.61 and 0.49-0.65 for men and 0.53-0.66 and 0.48-0.67 for women, respectively) and 6MWD (r range: 0.29-0.42 and 0.44-0.55 for men and 0.25-0.54 and 0.34-0.55 for women, respectively) (P < 0.001). Regression models demonstrated that QMS and QME were significant determinants of peakV̇o₂ (explained variance R² range: 35.6%-48.8% for men and 36.8%-49.0% for women) and 6MWD (R² range: 24.3%-43.3% for men and 28.4%-40.3% for women), independent of age and fat-free mass. Quadriceps muscle function was significantly associated with peakV̇o₂ and 6MWD in male and female patients with COPD after stratification for resting LF, in which QME appear to be a more important determinant than QMS. This underlines the importance of systematically evaluating both quadriceps muscle strength and endurance in in all patients with COPD.NEW & NOTEWORTHY Our findings identified quadriceps muscle function as an important determinant of exercise capacity across a wide spectrum of lung function. Quadriceps muscle endurance appears to be a more important determinant than quadriceps muscle strength, underlining the importance of including both the measurement of quadriceps muscle strength and endurance in routine assessment for all patient with COPD.

[Which physical tests for which objectives in pulmonary rehabilitation?]

Chronic respiratory disease is a major cause of morbidity and mortality worldwide and an important cause of disability including a reduction of exercise, functional and muscle capacity contributing to a decreased quality of life. In the context of pulmonary rehabilitation, a thorough patient-centered outcome assessment, including not only measures of lung function, but also exercise functional and muscle capacity, is imperative for a comprehensive disease management. Assessment of these impairments and dysfunctions with appropriate and change-sensitive procedures is thus necessary for personalizing the physical interventions and assessing the short- and long-term effectiveness of the intervention. The clinician currently has a wide variety of tests and measurements available to assess the physical and functional capacity of people with chronic respiratory disease. The aim of this review is to provide a pragmatic synthesis of the physical, functional and muscle capacity tests most commonly used in pulmonary rehabilitation. Ultimately, it should help the clinician to identify the relevant evaluations according to the objectives of the patients but also according to the available resources, the setting of pulmonary rehabilitation and the specific qualities of each test.

Cardiorespiratory Response during the 1-min Sit-to-Stand Test in Chronic Obstructive Pulmonary Disease

PURPOSE

This study aimed to assess the cardiorespiratory response during a 1-min sit-to-stand test (1STS) in comparison with cycling cardiopulmonary exercise test (CPET) in people with chronic obstructive pulmonary disease (COPD) and in healthy subjects and to evaluate whether 1STS may induce leg fatigue in these individuals.

METHODS

Fourteen people with severe COPD and 12 healthy subjects performed a 1STS and a CPET during which cardiorespiratory response, perception of dyspnea, and leg fatigue were assessed. Quadriceps strength was assessed before and after 1STS, and contractile fatigue was defined as a postexercise fall in quadriceps twitch force greater than 15% of resting values.

RESULTS

In COPD, peak V˙O2, V˙E, and HR achieved during 1STS reached 113%, 103%, and 93% of the corresponding values during CPET, respectively. Decrease in SpO2 from preexercise to peak exercise and the magnitude of dynamic hyperinflation were similar between 1STS and CPET. Borg dyspnea and leg fatigue scores were higher for CPET than 1STS. In healthy subjects, peak cardiorespiratory demand and symptom scores were higher during CPET compared with 1STS. A V˙O2 overshoot during recovery was observed only in people with COPD. After 1STS, the V˙O2 half-time recovery of COPD was 152 ± 25 s compared with 74 ± 18 in healthy subjects (P < 0.01). Ten people with COPD and five healthy subjects were considered as fatiguers.

CONCLUSION

The 1STS induced a similar cardiorespiratory stress to that of CPET and was associated with contractile quadriceps fatigue in people with severe COPD. The V˙O2 overshoot and slower recovery time of cardiorespiratory variables seen in COPD demonstrate the clinical relevance of monitoring the recovery phase of exercise.

The role of peripheral muscle fatigability on exercise intolerance in COPD

INTRODUCTION

Exercise limitation in chronic obstructive pulmonary disease (COPD) is multi-factorial; however, growing evidence indicates that muscle dysfunction may contribute in some patients.

AREAS COVERED

This work outlines current evidence for and against increased peripheral muscle fatigability in COPD through a comprehensive review of relevant literature available on PubMed/MEDLINE until May 2020. The authors first discuss key methodological issues relative to muscle fatigue assessment by non-volitional techniques, particularly magnetic stimulation. The authors then provide a detailed discussion of critical studies to have objectively measured skeletal muscle fatigue in individuals with COPD.

EXPERT OPINION

Current evidence indicates that localized (knee extension) and cycling exercise are associated with increased quadriceps fatigability in most COPD patients. Increased fatigability, however, has not been consistently found in response to walking, likely reflecting the tendency of 'central' respiratory constraints to overshadow potential functional impairments in the appendicular muscles in this form of exercise. Thus, addressing skeletal muscle abnormalities may be critical to translate improvements in lung mechanics (e.g., due to bronchodilator therapy) into better exercise tolerance. The positive effects of pulmonary rehabilitation on muscle fatigability are particularly encouraging and suggest a role for these measurements to test the efficacy of emerging adjunct training strategies focused on the peripheral muscles.

Determinants of the diminished exercise capacity in patients with chronic obstructive pulmonary disease: looking beyond the lungs

KEY POINTS

Peak oxygen uptake, a primary determinant of prognosis, mortality and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD), with mounting evidence supporting an important role for peripheral dysfunction, particularly within skeletal muscle. In patients with severe COPD and activity-matched controls, muscle oxygen transport and utilization were assessed at peak effort during single-leg knee-extensor exercise (KE), where ventilation is assumed to be submaximal. This strategy removes ventilation as the major constraint to exercise capacity in COPD, allowing maximal muscle function to be attained and evaluated. During maximal KE, both convective arterial oxygen delivery to the skeletal muscle microvasculature and subsequent diffusive oxygen delivery to the mitochondria were diminished in patients with COPD compared to control subjects. These findings emphasize the importance of factors, beyond the lungs, that influence exercise capacity in this patient population and may, ultimately, influence the prognosis, mortality and quality of life for patients with COPD.

ABSTRACT

Peak oxygen uptake ( V ̇ O 2 peak ), a primary determinant of prognosis, mortality and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD). Mounting evidence supports an important role of the periphery, particularly skeletal muscle, in the diminished V ̇ O 2 peak with COPD. However, the peripheral determinants of V ̇ O 2 peak have not been comprehensively assessed in this cohort. Thus, the hypothesis was tested that both muscle convective and diffusive oxygen (O2 ) transport, and therefore skeletal muscle peak O2 uptake ( V ̇ M O 2 peak ), are diminished in patients with COPD compared to matched healthy controls, even when ventilatory limitations (i.e. attainment of maximal ventilation) are minimized by using small muscle mass exercise. Muscle O2 transport and utilization were assessed at peak exercise from femoral arterial and venous blood samples and leg blood flow (by thermodilution) in eight patients with severe COPD (forced expiratory volume in 1s (FEV1 ) ± SEM = 0.9 ± 0.1 l, 30% of predicted) and eight controls during single-leg knee-extensor exercise. Both muscle convective O2 delivery (0.44 ± 0.06 vs. 0.69 ± 0.07 l min-1 , P < 0.05) and muscle diffusive O2 conductance (6.6 ± 0.8 vs. 10.4 ± 0.9 ml min-1  mmHg-1 , P < 0.05) were ∼1/3 lower in patients with COPD than controls, resulting in an attenuated V ̇ M O 2 peak in the patients (0.27 ± 0.04 vs. 0.42 ± 0.05 l min-1 , P < 0.05). When cardiopulmonary limitations to exercise are minimized, the convective and diffusive determinants of V ̇ M O 2 peak , at the level of the skeletal muscle, are greatly attenuated in patients with COPD. These findings emphasize the importance of factors, beyond the lungs, that may ultimately influence this population's prognosis, mortality and quality of life.

Locomotor Muscles in COPD: The Rationale for Rehabilitative Exercise Training

Exercise training as part of pulmonary rehabilitation is arguably the most effective intervention to improve tolerance to physical exertion in patients with chronic obstructive pulmonary disease (COPD). Owing to the fact that exercise training has modest effects on exertional ventilation, operating lung volumes and respiratory muscle performance, improving locomotor muscle structure and function are key targets for pulmonary rehabilitation in COPD. In the current concise review, we initially discuss whether patients’ muscles are exposed to deleterious factors. After presenting corroboratory evidence on this regard (e.g., oxidative stress, inflammation, hypoxemia, inactivity, and medications), we outline their effects on muscle macro- and micro-structure and related functional properties. We then finalize by addressing the potential beneficial consequences of different training strategies on these muscle-centered outcomes. This review provides, therefore, an up-to-date outline of the rationale for rehabilitative exercise training approaches focusing on the locomotor muscles in this patient population.

Quadriceps Endurance Increases Following Cycling Exercise With Non-Invasive Ventilation In Moderate-To-Severe COPD Patients. A Non-Randomized Controlled Study

Purpose

Application of non-invasive ventilation (NIV) during exercise improves exercise tolerance in severe COPD patients; however, the underlying mechanism is only partially unraveled. As part of its known effect to unload the respiratory muscles, we looked for the influence of NIV on post-exercise quadriceps muscle endurance.

Patients and methods

We included 25 severe COPD patients entering an outpatient pulmonary rehabilitation program. They performed, on successive days, three quadriceps endurance tests at 70% of the maximal strength (1RM) to task failure (TlimQ); 1) control condition; 2) following constant load cycling exercise to exhaustion without Inspiratory Pressure Support (TlimQ IPS-); 3) following the same cycling exercise with IPS (TlmQ IPS+).

Results

Dyspnea Borg score was significantly reduced at the end of the constant load cycling exercise with IPS+ compared to IPS- (3.5±2.6 to 4.3±2.3, p<0.05). Compared to controlled condition, TlimQ was reduced from 78.9±22.7 s to 64.7±22.1 s (p<0.01) with IPS+ and to 48.9±13.7 s (p<0.001) with IPS-. Sensitive analysis revealed a positive effect of NIV on TlimQ in only 15 of the 25 included patients (60%) and was unpredictable from exercise tolerance or maximal quadriceps strength.

Conclusion

Using a simple muscle endurance test, we showed the protective effect of NIV on the exercise-induced quadriceps dysfunction. This beneficial effect is inconstant in our small series of patients and could not be predicted by exercise capacity or endurance to exercise. However, measuring quadriceps muscle endurance following a session of exercise could determine in which patient NIV would improve the benefit of pulmonary rehabilitation.

Control of exercise hyperpnoea: Contributions from thin-fibre skeletal muscle afferents

NEW FINDINGS

What is the topic of this review? In this review, we examine the evidence for control mechanisms underlying exercise hyperpnoea, giving attention to the feedback from thin-fibre skeletal muscle afferents, and highlight the frequently conflicting findings and difficulties encountered by researchers using a variety of experimental models. What advances does it highlight? There has been a recent resurgence of interest in the role of skeletal muscle afferent involvement, not only as a mechanism of healthy exercise hyperpnoea but also in the manifestation of breathlessness and exercise intolerance in chronic disease.

ABSTRACT

The ventilatory response to dynamic submaximal exercise is immediate and proportional to metabolic rate, which maintains isocapnia. How these respiratory responses are controlled remains poorly understood, given that the most tightly controlled variable (arterial partial pressure of CO₂ /H⁺ ) provides no error signal for arterial chemoreceptors to trigger reflex increases in ventilation. This review discusses evidence for different postulated control mechanisms, with a focus on the feedback from group III/IV skeletal muscle mechanosensitive and metabosensitive afferents. This concept is attractive, because the stimulation of muscle mechanoreceptors might account for the immediate increase in ventilation at the onset of exercise, and signals from metaboreceptors might be proportional to metabolic rate. A variety of experimental models have been used to establish the contribution of thin-fibre muscle afferents in ventilatory control during exercise, with equivocal results. The inhibition of afferent feedback via the application of lumbar intrathecal fentanyl during exercise suppresses ventilation, which provides the most compelling supportive evidence to date. However, stimulation of afferent feedback at rest has no consistent effect on respiratory output. However, evidence is emerging for synergistic interactions between muscle afferent feedback and other stimulatory inputs to the central respiratory neuronal pool. These seemingly hyperadditive effects might explain the conflicting findings encountered when using different experimental models. We also discuss the increasing evidence that patients with certain chronic diseases exhibit exaggerated muscle afferent activation during exercise, resulting in enhanced cardiorespiratory responses. This might provide a neural link between the well-established limb muscle dysfunction and the associated exercise intolerance and exertional dyspnoea, which might offer therapeutic targets for these patients.

Prevalence and Risk Factors for Osteoporosis in Individuals With COPD: A Systematic Review and Meta-analysis

BACKGROUND

Osteoporosis is prevalent in individuals with COPD. Updated evidence is required to complement the previous systematic review on this topic to provide best practice. The aim of this systematic review and meta-analysis was to quantitatively synthesize data from studies with respect to the prevalence and risk factors for osteoporosis among individuals with COPD.

METHODS

EMBASE, CINAHL, MEDLINE, and PubMed databases were searched for articles containing the key words "COPD," "osteoporosis," "prevalence," and "risk factor." Eligibility screening, data extraction, and quality assessment of the retrieved articles were conducted independently by two reviewers. Meta-analyses were performed to determine osteoporosis prevalence and risk factors in individuals with COPD. Meta-regression analyses were conducted to explore the sources of heterogeneity.

RESULTS

The pooled global prevalence from 58 studies was 38% (95% CI, 34-43). The presence of COPD increased the likelihood of having osteoporosis (OR, 2.83). Other significant risk factors for osteoporosis in COPD patients were BMI < 18.5 kg/m² (OR, 4.26) and the presence of sarcopenia (OR, 3.65).

CONCLUSIONS

Osteoporosis is prevalent in individuals with COPD, and the prevalence seems to be high and similar in many countries. Patients with COPD should be screened for osteoporosis and contributing risk factors.

Fibroblast Growth Factor 23 is Associated with a Frequent Exacerbator Phenotype in COPD: A Cross-Sectional Pilot Study

Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory airway disease punctuated by exacerbations (AECOPD). Subjects with frequent AECOPD, defined by having at least two exacerbations per year, experience accelerated loss of lung function, deterioration in quality of life and increase in mortality. Fibroblast growth factor (FGF)23, a hormone associated with systemic inflammation and altered metabolism is elevated in COPD. However, associations between FGF23 and AECOPD are unknown. In this cross-sectional study, individuals with COPD were enrolled between June 2016 and December 2016. Plasma samples were analyzed for intact FGF23 levels. Logistic regression analyses were used to measure associations between clinical variables, FGF23, and the frequent exacerbator phenotype. Our results showed that FGF23 levels were higher in frequent exacerbators as compared to patients without frequent exacerbations. FGF23 was also independently associated with frequent exacerbations (OR 1.02; 95%CI 1.004–1.04; p = 0.017), after adjusting for age, lung function, smoking, and oxygen use. In summary, FGF23 was associated with the frequent exacerbator phenotype and correlated with number of exacerbations recorded retrospectively and prospectively. Further studies are needed to explore the role of FGF 23 as a possible biomarker for AECOPD to better understand the pathobiology of COPD and to help develop therapeutic targets.

Comparison of multi-tissue aging between human and mouse

With the rapid growth of the aging population, exploring the biological basis of aging and related molecular mechanisms has become an important topic in modern scientific research. Aging can cause multiple organ function attenuations, leading to the occurrence and development of various age-related metabolic, nervous system, and cardiovascular diseases. In addition, aging is closely related to the occurrence and development of tumors. Although a number of studies have used various mouse models to study aging, further research is needed to associate mouse and human aging at the molecular level. In this paper, we systematically assessed the relationship between human and mouse aging by comparing multi-tissue age-related gene expression sets. We compared 18 human and mouse tissues, and found 9 significantly correlated tissue pairs. Functional analysis also revealed some terms related to aging in human and mouse. And we performed a crosswise comparison of homologous age-related genes with 18 tissues in human and mouse respectively, and found that human Brain_Cortex was significantly correlated with Brain_Hippocampus, which was also found in mouse. In addition, we focused on comparing four brain-related tissues in human and mouse, and found a gene-GFAP-related to aging in both human and mouse.

Cardiorespiratory and Muscle Oxygenation Responses to Isokinetic Exercise in Chronic Obstructive Pulmonary Disease

PURPOSE

This study aimed to describe cardiorespiratory, quadriceps oxygenation, and muscle fatigue responses during a one-legged quadriceps isokinetic endurance exercise in chronic obstructive pulmonary disease (COPD) and control subjects.

METHODS

Fourteen patients with COPD and 14 control subjects performed a cardiopulmonary cycling exercise test to exhaustion to assess peak oxygen consumption (V˙O2peak), minute ventilation (V˙Epeak), and heart rate (HRpeak). They also performed a quadriceps isokinetic endurance exercise consisting in 30 maximal knee extensions at 90°·s with continuous monitoring of expired gases, cardiac output, and oxygenation of the quadriceps by near-infrared spectroscopy. Total muscle work and fatigue index were also quantified.

RESULTS

The total muscle work developed during the quadriceps isokinetic endurance exercise was 2.25 ± 0.57 kJ in COPD and 3.12 ± 0.60 kJ in controls, P < 0.001. In absolute terms, there were no between-group differences in V˙O2, V˙E, cardiac output, and HR at the end of quadriceps isokinetic endurance exercise. However, V˙E and HR reported that a fraction of their respective peak values during cardiopulmonary cycling exercise test were higher in COPD (V˙E/V˙Epeak, 69% ± 3%; HR/HRpeak, 82% ± 15%) compared with controls (V˙E/V˙Epeak, 45% ± 2%; HR/HRpeak, 71% ± 13%), all P < 0.05. During quadriceps isokinetic endurance exercise, quadriceps deoxyhemoglobin increased by 47% ± 31% in patients versus 33% ± 41% in controls (P < 0.05 from rest values) with a significant between-group differences (P = 0.025). The fatigue index during the quadriceps exercise was higher in COPD compared with controls.

CONCLUSIONS

Although one-legged quadriceps isokinetic endurance exercise resulted in substantial central cardiorespiratory demands in COPD, this exercise was nevertheless associated with muscle overload as evidenced by muscle deoxygenation and higher muscle fatigue index in COPD compared with controls. These findings may have implications of the design of exercise training programs in COPD.

Acute effects of photobiomodulation therapy (PBMT) combining laser diodes, light-emitting diodes, and magnetic field in exercise capacity assessed by 6MST in patients with COPD: a crossover, randomized, and triple-blinded clinical trial

Chronic obstructive pulmonary disease (COPD) is characterized by dyspnea, as well as musculoskeletal and systemic manifestations. Photobiomodulation therapy (PBMT) with use of low-level laser therapy (LLLT) and/or light-emitting diode therapy (LEDT) is an electrophysical intervention that has been found to minimize or delay muscle fatigue. The aim of this study was to evaluate the acute effect of PBMT with combined use of lasers diodes, light-emitting diodes (LEDs), magnetic field on muscle performance, exercise tolerance, and metabolic variables during the 6-minute stepper test (6MST) in patients with COPD. Twenty-one patients with COPD (FEV₁ 46.3% predicted) completed the 6MST protocol over 2 weeks, with one session per week. PBMT/magnetic field or placebo (PL) was performed before each 6MST (17 sites on each lower limb, with a dose of 30 J per site, using a cluster of 12 diodes 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm red LEDs; Multi Radiance Medical™, Solon, OH, USA). Patients were randomized into two groups before the test according to the treatment they would receive. Assessments were performed before the start of each protocol. The primary outcomes were oxygen uptake and number of steps, and the secondary outcome was perceived exertion (dyspnea and fatigue in the lower limbs). PBMT/magnetic field applied before 6MST significantly increased the number of steps during the cardiopulmonary exercise test when compared to the results with placebo (129.8 ± 10.6 vs 116.1 ± 11.5, p = 0.000). PBMT/magnetic field treatment also led to a lower score for the perception of breathlessness (3.0 [1.0-7.0] vs 4.0 [2.0-8.0], p = 0.000) and lower limb fatigue (2.0 [0.0-5.0] vs 4.0 [0.0-7.0], p = 0.001) compared to that with placebo treatment. This study showed that the combined application of PBMT and magnetic field increased the number of steps during the 6MST and decreased the sensation of dyspnea and lower limb fatigue in patients with COPD.

Ventilation distribution, pulmonary diffusion and peripheral muscle endurance as determinants of exercise intolerance in elderly patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a progressive and disabling disease that has been associated with aging. Several factors may potentially impair performance during exercise in elderly patients with COPD. This study was conducted to evaluate what characteristics related to lung function, peripheral muscle strength and endurance can predict the performance of elderly patients with COPD during cardiopulmonary exercise testing (CPET). Forty elderly patients with COPD underwent resting lung function tests, knee isokinetic dynamometry, and CPET. Three models were developed to explain the variability in peak oxygen uptake (VO(2) peak) after controlling for age as an independent confounder. The pulmonary function model showed the highest explained variance (65.6 %); in this model, ventilation distribution (p<0.001) and pulmonary diffusion (0.013) were found to be independent predictors. Finally, the models that included the muscle strength and endurance variables presented explained variances of 51 % and 57.4 %, respectively. In these models that involved muscular dysfunction, however, only the endurance variables were found to be independent predictors (p<0.05). In conclusion, ventilation distribution and pulmonary diffusion, but not the degree of airway obstruction, independently predict CPET performance in elderly patients with COPD. In addition, peripheral muscle endurance, but not strength, also predicts CPET performance in these subjects.

Nutritional status and muscle dysfunction in chronic respiratory diseases: stable phase versus acute exacerbations

Nutritional abnormalities are frequent in different chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD), bronchiectasis, cystic fibrosis (CF), interstitial fibrosis and lung cancer, having important clinical consequences. However, nutritional abnormalities often remained underdiagnosed due to the relative lack of awareness of health professionals. Therefore, systematic anthropometry or even better, assessment of body composition, should be performed in all patients with chronic respiratory conditions, especially following exacerbation periods when malnutrition becomes more accentuated. Nutritional abnormalities very often include the loss of muscle mass, which is an important factor for the occurrence of muscle dysfunction. The latter can be easily detected with the specific assessment of muscle strength and endurance, and also negatively influences patients' quality of life and prognosis. Both nutritional abnormalities and muscle dysfunction result from the interaction of several factors, including tobacco smoking, low physical activity-sedentarism, systemic inflammation and the imbalance between energy supply and requirements, which essentially lead to a negative balance between protein breakdown and synthesis. Therapeutic approaches include improvements in lifestyle, nutritional supplementation and training. Anabolic drugs may be administered in some cases.

Reliability and validity of the Chinese version of the Breathlessness Beliefs Questionnaire

The aim of this article is to evaluate the reliability and validity of the Chinese version of the Breathlessness Beliefs Questionnaire (BBQ) for use among patients with respiratory diseases in China. The BBQ is an instrument for assessing specific dyspnoea-related fears and may have predictive value for chronic obstructive pulmonary disease outcomes beyond general anxiety measures. This instrument has not previously been translated into Chinese or tested in mainland China. This was a cross-sectional validation study with a 1-week test of reproducibility. A total of 252 Chinese patients with respiratory diseases recruited from pulmonary outpatient and inpatient departments completed the BBQ. Demographic characteristics, pulmonary function and degree of dyspnoea were also measured. Cronbach's α was 0.82 for the total BBQ score; 0.72 for the somatic focus subscale and 0.73 for the activity avoidance subscale. Test-retest reliability was satisfactory, with intraclass correlation coefficient scores for the BBQ overall and for each subscale ranging from 0.96 to 0.98 ( p < 0.001). After exploratory factor analyses, the Chinese version of the BBQ was found to be similar to the original Dutch version. The Chinese version of the BBQ is a reliable tool to assess dyspnoea-related fear in patients with respiratory diseases in mainland China.

Reduced HDAC2 in skeletal muscle of COPD patients

Background

Skeletal muscle weakness in chronic obstructive pulmonary disease (COPD) is an important predictor of poor prognosis, but the molecular mechanisms of muscle weakness in COPD have not been fully elucidated. The aim of this study was to investigate the role of histone deacetylases(HDAC) in skeletal muscle weakness in COPD.

Methods and results

Twelve COPD patients, 8 smokers without COPD (SM) and 4 healthy non-smokers (NS) were recruited to the study. HDAC2 protein expression in quadriceps muscle biopsies of COPD patients (HDAC2/β-actin: 0.59 ± 0.34) was significantly lower than that in SM (1.9 ± 1.1, p = 0.0007) and NS (1.2 ± 0.7, p = 0.029). HDAC2 protein in skeletal muscle was significantly correlated with forced expiratory volume in 1 s % predicted (FEV₁ % pred) (r_s = 0.53, p = 0.008) and quadriceps maximum voluntary contraction force (MVC) (r_s = 0.42, p = 0.029). HDAC5 protein in muscle biopsies of COPD patients (HDAC5/β-actin: 0.44 ± 0.26) was also significantly lower than that in SM (1.29 ± 0.39, p = 0.0001) and NS (0.98 ± 0.43, p = 0.020). HDAC5 protein in muscle was significantly correlated with FEV₁ % pred (r_s = 0.64, p = 0.0007) but not with MVC (r_s = 0.30, p = 0.180). Nuclear factor-kappa B (NF-κB) DNA binding activity in muscle biopsies of COPD patients (10.1 ± 7.4) was significantly higher than that in SM (3.9 ± 7.3, p = 0.020) and NS (1.0 ± 1.2, p = 0.004and significantly correlated with HDAC2 decrease (r_s = −0.59, p = 0.003) and HDAC5 (r_s = 0.050, p = 0.012). HDAC2 knockdown by RNA interference in primary skeletal muscle cells caused an increase in NF-κB activity, NF-κB acetylation and basal tumour necrosis factor (TNF)-α production, as well as progressive cell death through apoptosis.

Conclusion

Skeletal muscle weakness in COPD may result from HDAC2 down-regulation in skeletal muscle via acetylation and activation of NF-κB. The restoration of HDAC2 levels might be a therapeutic target for improving skeletal muscle weakness in COPD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0588-8) contains supplementary material, which is available to authorized users.

Standardized Method to Measure Muscle Force at the Bedside in Hemodialysis Patients

OBJECTIVES

In hemodialysis, diminution of muscle strength constitutes a major prognostic factor of mortality. Currently, measurement of quadriceps isometric maximal voluntary force (MVF) represents the reference method to investigate muscle strength. However, reduction of MVF is rarely detected in these patients due to the absence of portative bedside tools in clinical practice. The purposes of this study were therefore to assess the agreement of a belt-stabilized handheld dynamometer (HHD) with the dynamometer chair (reference method) and to determine intratester and intertester reliability of the quadriceps MVF measurements using belt-stabilized HHD in healthy subjects and in hemodialysis patients.

DESIGN

Repeated-measures cross-sectional study.

SETTING

Clinical and academic hospital.

PARTICIPANTS

Fifty-three healthy adult subjects (23 males, 36.5 + 12.5 y.o.) and 21 hemodialysis patients (14 males, 72.4 + 13.3 y.o., dialysis vintage 30 + 75.1 months).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURE

MVF measurements were assessed with belt-stabilized HHD and dynamometer chair, by two independent investigators. The agreement between the two devices would be quantified using the Bland-Altman 95% limits of agreement (LOA) method and the Spearman correlation.

RESULTS

For healthy subjects and hemodialysis patients, Spearman coefficients between belt-stabilized HHD and dynamometer chair were 0.63 and 0.75, respectively (P < .05). In hemodialysis group, reliability was excellent for both the intratester and intertester reliability R² = 0.85 (P < .01) and R² = 0.90 (P < .01), respectively. In all individuals, the mean difference between the dynamometer chair and the belt-stabilized HHD was -13.07 ± 21.77 N.m. (P < .001). The LOA for the upper and the lower was 29.59 and -55.73 N.m., respectively.

CONCLUSION

In healthy subjects and in hemodialysis patients, the belt-stabilized HHD dynamometer appears as a valid and reliable method to measure in clinical practice isometric MVF of quadriceps in hemodialysis patients. Therefore, the belt-stabilized HHD appears as a suitable and a relevant diagnostic tool for the identification of muscle dysfunction in hemodialysis patients.

Clinical management of chronic obstructive pulmonary disease patients with muscle dysfunction

Muscle dysfunction is frequently observed in chronic obstructive pulmonary disease (COPD) patients, contributing to their exercise limitation and a worsening prognosis. The main factor leading to limb muscle dysfunction is deconditioning, whereas respiratory muscle dysfunction is mostly the result of pulmonary hyperinflation. However, both limb and respiratory muscles are also influenced by other negative factors, including smoking, systemic inflammation, nutritional abnormalities, exacerbations and some drugs. Limb muscle weakness is generally diagnosed through voluntary isometric maneuvers such as handgrip or quadriceps muscle contraction (dynamometry); while respiratory muscle loss of strength is usually recognized through a decrease in maximal static pressures measured at the mouth. Both types of measurements have validated reference values. Respiratory muscle strength can also be evaluated determining esophageal, gastric and transdiaphragmatic maximal pressures although there is a lack of widely accepted reference equations. Non-volitional maneuvers, obtained through electrical or magnetic stimulation, can be employed in patients unable to cooperate. Muscle endurance can also be assessed, generally using repeated submaximal maneuvers until exhaustion, but no validated reference values are available yet. The treatment of muscle dysfunction is multidimensional and includes improvement in lifestyle habits (smoking abstinence, healthy diet and a good level of physical activity, preferably outside), nutritional measures (diet supplements and occasionally, anabolic drugs), and different modalities of general and muscle training.

Review: Systemic consequences of COPD

Chronic obstructive pulmonary disease (COPD) is a highly prevalent chronic lung condition, affecting ∼10% of adults over the age of 40 years in the western world. Research over the past 10 years has shown that COPD is more than just a lung disorder; it affects other end-organs including the cardiovascular and the musculoskeletal systems, making it a multi-component, multi-system disease. COPD increases the risk for ischemic heart disease, stroke, osteoporosis, cachexia, and muscle weakness by two to threefold, independent of other factors such as smoking and age. The mechanisms by which COPD affects these end-organs, however, are unclear. In this paper, we review some of the common and serious extra-pulmonary manifestations of COPD and the potential mechanisms by which they can be linked with COPD.

Ventilatory responses to muscle metaboreflex activation in chronic obstructive pulmonary disease

KEY POINTS

Recent evidence indicates a role for group III/IV muscle afferents in reflex control of the human ventilatory response to exercise. Dyspnoea in chronic obstructive pulmonary disease (COPD) may be linked to this reflex response. This study shows that activation of the muscle metaboreflex causes a ventilatory response in COPD patients but not in healthy controls. This indicates abnormal involvement of muscle afferents in the control of ventilation in COPD which may be a contributing factor to exercise dyspnoea.

ABSTRACT

Blockade of thin fibre muscle afferent feedback during dynamic exercise reduces exercise hyperpnoea in health and chronic obstructive pulmonary disease (COPD). Therefore, we hypothesised that activation of the muscle metaboreflex at rest would cause hyperpnoea. We evaluated the effect of muscle metaboreflex activation on ventilation, in resting COPD patients and healthy participants. Following a bout of rhythmic hand grip exercise, post exercise circulatory occlusion (PECO) was applied to the resting forearm to sustain activation of the muscle metaboreflex, in 18 COPD patients (FEV₁ /FVC ratio < 70%), 9 also classified as chronically hypercapnic, and 9 age- and gender-matched controls. The cardiovascular response to exercise and the sustained blood pressure elevation during PECO was similar in patients and controls. During exercise ventilation increased by 6.64 ± 0.84 in controls and significantly (P < 0.05) more, 8.38 ± 0.81 l min^-1 , in patients. During PECO it fell to baseline levels in controls but remained significantly (P < 0.05) elevated by 2.78 ± 0.51 l min^-1 in patients until release of circulatory occlusion, with no significant difference in responses between patient groups. Muscle metaboreflex activation causes increased ventilation in COPD patients but not in healthy participants. Chronic hypercapnia in COPD patients does not exaggerate this response. The muscle metaboreflex appears to be abnormally involved in the control of ventilation in COPD and may be a contributing factor to exercise dyspnoea.

Tai Chi for chronic obstructive pulmonary disease (COPD)

BACKGROUND

Tai Chi, a systematic callisthenic exercise first developed in ancient China, involves a series of slow and rhythmic circular motions. It emphasises use of 'mind' or concentration to control breathing and circular body motions to facilitate flow of internal energy (i.e. 'qi') within the body. Normal flow of 'qi' is believed to be essential to sustain body homeostasis, ultimately leading to longevity. The effect of Tai Chi on balance and muscle strength in the elderly population has been reported; however, the effect of Tai Chi on dyspnoea, exercise capacity, pulmonary function and psychosocial status among people with chronic obstructive pulmonary disease (COPD) remains unclear.

OBJECTIVES

• To explore the effectiveness of Tai Chi in reducing dyspnoea and improving exercise capacity in people with COPD.• To determine the influence of Tai Chi on physiological and psychosocial functions among people with COPD.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register of trials (which included the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Allied and Complementary Medicine Database (AMED) and PsycINFO); handsearched respiratory journals and meeting abstracts; and searched Chinese medical databases including Wanfang Data, Chinese Medical Current Contents (CMCC), Chinese Biomedical Database (CBM), China Journal Net (CJN) and China Medical Academic Conference (CMAC), from inception to September 2015. We checked the reference lists of all primary studies and review articles for relevant additional references.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing Tai Chi (Tai Chi alone or Tai Chi in addition to another intervention) versus control (usual care or another intervention identical to that used in the Tai Chi group) in people with COPD. Two independent review authors screened and selected studies.

DATA COLLECTION AND ANALYSIS

Two independent review authors extracted data from included studies and assessed risk of bias on the basis of suggested criteria listed in the Cochrane Handbook for Systematic Reviews of Interventions. We extracted post-programme data and entered them into RevMan software (version 5.3) for data synthesis and analysis.

MAIN RESULTS

We included a total of 984 participants from 12 studies (23 references) in this analysis. We included only those involved in Tai Chi and the control group (i.e. 811 participants) in the final analysis. Study sample size ranged from 10 to 206, and mean age ranged from 61 to 74 years. Programmes lasted for six weeks to one year. All included studies were RCTs; three studies used allocation concealment, six reported blinded outcome assessors and three studies adopted an intention-to-treat approach to statistical analysis. No adverse events were reported. Quality of evidence of the outcomes ranged from very low to moderate.Analysis was split into three comparisons: (1) Tai Chi versus usual care; (2) Tai Chi and breathing exercise versus breathing exercise alone; and (3) Tai Chi and exercise versus exercise alone.Comparison of Tai Chi versus usual care revealed that Tai Chi demonstrated a longer six-minute walk distance (mean difference (MD) 29.64 metres, 95% confidence interval (CI) 10.52 to 48.77 metres; participants = 318; I(2) = 59%) and better pulmonary function (i.e. forced expiratory volume in one second, MD 0.11 L, 95% CI 0.02 to 0.20 L; participants = 258; I(2) = 0%) in post-programme data. However, the effects of Tai Chi in reducing dyspnoea level and improving quality of life remain inconclusive. Data are currently insufficient for evaluating the impact of Tai Chi on maximal exercise capacity, balance and muscle strength in people with COPD. Comparison of Tai Chi and other interventions (i.e. breathing exercise or exercise) versus other interventions shows no superiority and no additional effects on symptom improvement nor on physical and psychosocial outcomes with Tai Chi.

AUTHORS' CONCLUSIONS

No adverse events were reported, implying that Tai Chi is safe to practise in people with COPD. Evidence of very low to moderate quality suggests better functional capacity and pulmonary function in post-programme data for Tai Chi versus usual care. When Tai Chi in addition to other interventions was compared with other interventions alone, Tai Chi did not show superiority and showed no additional effects on symptoms nor on physical and psychosocial function improvement in people with COPD. With the diverse style and number of forms being adopted in different studies, the most beneficial protocol of Tai Chi style and number of forms could not be commented upon. Hence, future studies are warranted to address these topics.

Challenges and Current Efforts in the Development of Biomarkers for Chronic Inflammatory and Remodeling Conditions of the Lungs

This review discusses biomarkers that are being researched for their usefulness to phenotype chronic inflammatory lung diseases that cause remodeling of the lung's architecture. The review focuses on asthma, chronic obstructive pulmonary disease (COPD), and pulmonary hypertension. Bio-markers of environmental exposure and specific classes of biomarkers (noncoding RNA, metabolism, vitamin, coagulation, and microbiome related) are also discussed. Examples of biomarkers that are in clinical use, biomarkers that are under development, and biomarkers that are still in the research phase are discussed. We chose to present examples of the research in biomarker development by diseases, because asthma, COPD, and pulmonary hypertension are distinct entities, although they clearly share processes of inflammation and remodeling.

Effect of endurance training on expiratory flow limitation and dynamic hyperinflation in patients with stable chronic obstructive pulmonary disease

BACKGROUND

Expiratory flow limitation (EFL) is the primary pathophysiological hallmark of chronic obstructive pulmonary disease (COPD). However, the effect of lower-extremity endurance training alone on EFL in patients with COPD remains largely unknown.

AIM

This study aims to determine the effects of endurance training on EFL and dynamic hyperinflation in patients with stable COPD.

METHODS

This was a prospective, single-blinded, non-randomised controlled 12-week study recruiting Chinese patients with stable COPD in an endurance training group (n = 15) or a control group (n = 13). Before and at the end of the study, we measured the EFL, pulmonary function, peak inspiratory flow (PIF) and maximum inspiratory pressure (MIP); moreover, the patients underwent a constant work rate exercise test in which Borg dyspnoea scale, tidal breathing flow volume curves and inspiratory capacity (IC) were determined every other minute.

RESULTS

Exercise training significantly improved the exercise endurance time (7.00 ± 3.05 vs 18.13 ± 6.44 min, P < 0.001), MIP (69.49 ± 16.03 vs 80.18 ± 15.97 cmH2 O, P < 0.001) and PIF (3.96 ± 1.01 vs 4.51 ± 1.13 L/s, P = 0.014), but not EFL (3.33 ± 0.49 vs 3.40 ± 0.51, P = 0.334). Subjects on training had decreased breathing frequency (26.26 ± 7.13 vs 23.15 ± 5.34 breaths/min, P = 0.002), minute ventilation (30.28 ± 7.52 vs 26.85 ± 4.17 L, P = 0.013), tidal peak expiratory flow (1.53 ± 0.22 vs 1.32 ± 0.20 L/s, P = 0.006), mean expiratory flow (0.87 ± 0.19 vs 0.68 ± 0.15 L/s, P = 0.011) and Borg dyspnoea score (7.20 ± 1.15 vs 3.93 ± 1.39, P < 0.001), as well as increased IC (1.50 ± 0.34 vs 1.67 ± 0.45 L, P = 0.002), expiratory time (1.47 ± 0.62 vs 1.72 ± 0.62 s, P = 0.004) and inspiratory flow reserve (2.05 ± 1.10 vs 2.95 ± 1.19 L/s, P = 0.002) at isotime. These changes were not observed in the control group.

CONCLUSION

Endurance training may benefit stable COPD patients in improving exercise endurance, inspiratory muscle strength, ventilatory requirements, exercise-induced hyperinflation and exertional dyspnoea.

Lung function in elderly subjects with metabolic syndrome and type II diabetes : Data from the Berlin Aging Study II

BACKGROUND

Previous studies have indicated a relationship between type II diabetes (T2D), metabolic syndrome (MetS) and pulmonary function but the pathological mechanism responsible remains unclear. The aim of the current analysis within the Berlin Aging Study II (BASE-II) was to investigate the influence of abdominal obesity and muscle mass on pulmonary function in subjects with T2D and MetS.

MATERIAL AND METHODS

A prebronchodilator pulmonary function test was carried out in 1369 subjects from the BASE-II (mean age 69 ± 4 years, 51.6 % women) where T2D was defined according to the German Diabetes Association (DDG) criteria, MetS according to the criteria of the International Diabetes Foundation (IDF), American Heart Association (AHA) and National Heart, Lung and Blood Institute (NHLBI) criteria from 2009 and pulmonary obstruction (obstructive lung disease, OLD) by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria of a forced expiratory volume in 1 s (FEV1 and forced vital capacity (FVC) ratio < 70 %.

RESULTS

Of the subjects 50.9 % achieved a sufficient level of quality according to the GOLD guidelines and were analyzed with respect to the research question. The FEV1 and FVC were decreased in study participants with T2D and MetS and the lung volume decreased with an increasing number of MetS criteria. Parameters of body composition, such as waist circumference and muscle mass had a significant influence on lung volumes, independent of MetS or T2D.

DISCUSSION

In this study MetS and T2D were associated with decreased lung volumes; however, muscle mass and abdominal obesity proved to be the most important factors influencing pulmonary function and could thus form the link between pulmonary function and MetS or T2D. Measurement of grip strength for the determination of muscle mass and waist circumference for determining abdominal obesity could contribute to the interpretation of the results of pulmonary function tests.

Effects of a six-month walking intervention on depression in inactive post-menopausal women: a randomized controlled trial

OBJECTIVES

Physical inactivity and advanced age are associated with risk of depressive disorders. Physical activity can reduce depressive symptoms in older subjects with depressive disorders. We investigated whether a walking intervention program may decrease the occurrence of depressive symptoms in inactive post-menopausal women without depression.

METHOD

A total of 121 participants aged 57-75 years were randomly assigned to a six-month moderate intensity walking intervention (three times a week, 40 minutes per session, supervised and home-based) or to a control group (waiting list). Inactivity was assessed using the Physical Activity Questionnaire for the Elderly. Depression levels were measured pre- and post-intervention with the Beck depression inventory (BDI). Several baseline measures were considered as possible predictors of post-intervention BDI score.

RESULTS

Participants in the walking intervention showed a significant decrease in depression as compared with controls. Baseline cognitive-BDI subscore, subjective health status, body mass index and adherence were post-intervention BDI score predictors.

CONCLUSION

A six-month, three-session per week, moderate intensity walking intervention with a minimal 50% adherence rate reduces depression in post-menopausal women at risk for depression due to physical inactivity. This type of walking intervention could be considered as a widely accessible prevention strategy to prevent depressive symptoms in post-menopausal women at risk of depression.

Test-retest reliability of lower limb isokinetic endurance in COPD: A comparison of angular velocities

Background

The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD).

Methods

After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV₁) 55%±18% predicted) performed two quadriceps isokinetic endurance tests on two separate occasions within a 5–7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV₁ for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated.

Results

High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities.

Conclusion

Despite a limited sample size, our findings support the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work) at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index could also be assessed reliably at 90° per second. Evaluation of dyspnea and leg fatigue using the modified Borg scale of perceived exertion was poorly reliable and its clinical usefulness is questionable. These results should be useful in the design and interpretation of future interventions aimed at improving muscle endurance in COPD.

Muscular and functional effects of partitioning exercising muscle mass in patients with chronic obstructive pulmonary disease - a study protocol for a randomized controlled trial

BACKGROUND

Low-load, high-repetitive single-limb resistance training may increase limb muscle function and functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD) while minimizing the occurrence of limiting exertional symptoms. Whether high-repetitive single-limb resistance training would perform better than high-repetitive two-limb resistance training is unknown. In addition, the mechanisms underlying possible benefits of high-repetitive resistance training has not been investigated. The aims of this study are to compare single versus two-limb high-repetitive resistance training in patients with COPD and to investigate mechanisms of action of these training modalities.

METHODS/DESIGN

This trial is a prospective, assessor-blind, randomized controlled trial. The participants are patients with stable severe to very severe COPD who are older than 40 years of age and healthy controls. The intervention is single-limb, high-repetitive, resistance training with elastic bands, three times/week for 8 weeks. The control is two-limb high-repetitive resistance training with elastic bands, three times/week for 8 weeks. The primary outcomes is change in the 6-min walking distance after 8 weeks of single-limb or two-limb high-repetitive resistance training. The secondary outcomes are changes in limb muscle strength and endurance capacity, key protein involved in quadriceps anabolic/catabolic signalization, fiber-type distribution and capillarization, subjective dyspnea and muscle fatigue, muscle oxygenation, cardiorespiratory demand and health-related quality-of-life after 8 weeks of single-limb or two-limb high-repetitive resistance training. The acute effects of single-limb versus two-limb high-repetitive resistance training on contractile fatigue, exercise stimulus (the product of number of repetition and load), subjective dyspnea and muscle fatigue, muscle oxygenation, and cardiorespiratory demand during upper and lower limb exercises will also be investigated in patients with COPD and healthy controls. Randomization will be performed using a random number generator by a person independent of the recruitment process, using 1:1 allocation to the intervention and the control group using random block sizes.

BLINDING

All outcome assessors will be blinded to group assignment.

DISCUSSION

The results of this project will provide important information to help developing and implementing customized exercise training programs for patients with COPD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02283580 Registration date: 4 November 2014. First participant randomized: 10 November 2014.

Relationship between vitamin D and lung function, physical performance and balance on patients with stage I-III chronic obstructive pulmonary disease

Summary Objectives: vitamin D is important for muscle function and it affects different aspects of muscle metabolism. This study aim to determine whether serum 25(OH) D levels are related to lung functions, physical performance and balance in patients with chronic obstructive pulmonary disease (COPD). Methods: in 90 patients with COPD and 57 healthy controls lung function tests, physical performance tests (time up and go, gait velocity test, sit-to-stand test, isometric strength, isokinetic strength), static (functional reach test) and dynamic (time up and go) balance tests and the association of 25(OH)D levels with lung functions, physical performance and balance were evaluated. Results: the COPD patients had significantly more deficit in physical function and balance parameters, and in dynamic balance test (p<0.005). Isokinetic knee muscle strength (flexor and extensor) in COPD patients was significantly lower than in the controls (p<0.05); FEV1 (p=0.008), FVC (p=0.02), FEV1/FVC (p=0.04), TLC (p=0.01) were lower in COPD patients with vitamin D deficiency [25(OH) D less than 15ng/mL] than in COPD patients without vitamin D deficiency. Hand grip test (p=0.000) and isokinetic knee muscle strength (flexor and extensor) (p<0.05) were also lower in COPD patients with vitamin D deficiency. Vitamin D deficiency was more pronounced in patients with stage III COPD (p<0.05). Conclusion: patients with COPD had worst physical functioning, poor balance and less muscle strength. Severe disturbed lung and peripheral muscle functions are more pronounced in COPD patients with vitamin D deficiency.

Improvements in patient-reported outcomes: A prospective, non-interventional study with aclidinium bromide for treatment of COPD

BACKGROUND

The inhaled long-acting muscarinic antagonist aclidinium bromide has been shown to significantly improve lung function parameters and symptom severity in patients with COPD in randomised placebo- and active-controlled clinical studies. To obtain a comprehensive view of the treatment effects, patient-reported outcomes were investigated in a real-life COPD population in routine clinical practice in Austria.

METHODS

Multicentre, prospective, non-interventional study in patients with COPD who were newly initiated on treatment with Eklira® Genuair® (aclidinium bromide; recommended dose 400 μg twice daily) as first-line or add-on therapy. Patients were either treatment naïve or switched from other COPD medications. Health-related quality of life by means of the COPD Assessment Test™ (CAT) and symptom-related variables were evaluated at the first visit (baseline) and after approximately 12 weeks of treatment. Features of the inhaler were assessed by patients and physicians at the follow-up visit.

RESULTS

A total of 795 COPD patients (56% male; median age: 64 years) were enrolled and treated. During the observational period, the proportion of patients with at least moderate nighttime symptoms, early-morning symptoms, and limitations in morning activities decreased from 45.0% to 21.4%, from 57.7% to 26.0%, and from 49.9% to 25.3%, respectively. All improvements from baseline in symptom severity and activity limitation were statistically significant (p < 0.0001, all tests). The mean (±SD) frequency of nocturnal awakenings decreased from 1.2 (±1.4) to 0.7 (±1.2) times per night (p < 0.0001). Quality of life improved significantly in patients treated with aclidinium bromide over 3 months compared to baseline (p < 0.0001; mean CAT total score: 18.5 ± 7.5 vs. 13.8 ± 7.3). Up to 90% of the patients and up to 91% of the physicians assessed individual features of the inhaler as 'very good' or 'good'. Aclidinium bromide was well tolerated; 6.9% of the patients reported adverse drug reactions, none of which were serious.

CONCLUSIONS

This non-interventional study indicated beneficial effects of Eklira® Genuair® in the treatment of COPD with regard to nighttime and early-morning symptoms, limitation of morning activities, and quality of life under routine conditions. The acceptance of the inhaler device was high, which is a prerequisite to ensure adherence in long-term therapy.

Vitamin D deficiency at 16 to 20 weeks' gestation is associated with impaired lung function and asthma at 6 years of age

RATIONALE

Vitamin D deficiency is associated with chronic lung disease. We have previously shown in an in vivo mouse model that maternal vitamin D deficiency is associated with alterations in early life lung structure and function. However, there are limited data to support a relationship between maternal vitamin D deficiency during the early stages of lung development and postnatal lung function in human populations.

OBJECTIVES

To assess the association between maternal vitamin D deficiency, postnatal lung function, and asthmatic status in a longitudinal birth cohort.

METHODS

Serum was collected at 16 to 20 weeks' gestation at the time of recruitment in a community-based prospective birth cohort for measurement of vitamin D (25[OH]D). Lung function was assessed by spirometry according to American Thoracic Society guidelines in children at 6 and 14 years of age. Demographic and clinical history data were collected by questionnaire at recruitment and at the follow-up visits.

MEASUREMENTS AND MAIN RESULTS

FVC Z-scores in both sexes (β, 0.007 [95% confidence interval (CI), 0.001-0.013]; P = 0.02) and FEV1 Z-scores in girls (β, 0.007 [95% CI, 0.001-0.013]; P = 0.02) were positively associated with maternal serum 25(OH)D at 6 years of age. These associations were mostly absent at 14 years of age. Maternal vitamin D deficiency was positively associated with asthma at 6 years of age but only in boys (odds ratio, 3.03 [95% CI, 1.02-9.02]; P = 0.04).

CONCLUSIONS

This study supports the notion that vitamin D deficiency during lung development may impact on postnatal lung growth and increase the risk of developing lung disease.

Physical Activity Monitoring in Patients with Chronic Obstructive Pulmonary Disease

Reduced physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD) is associated with increased morbidity and mortality (e.g. exacerbations) and eventually leads to disability, depression, and social and physical isolation. Measuring PA in this population is important to accurately characterize COPD and to help clinicians during a baseline evaluation and patient follow-up. Also, it may help increase adherence to PA programs. There are reliable objective and subjective methods available to measure PA. Recently, several new monitors have been developed that have improved accuracy of such measurements. Because these devices provide real-time feedback, they may help to improve participant self-motivation strategies and reinforce daily lifestyle modifications, one of the main goals in COPD management. This review focuses on describing available instruments to measure PA, specifically in patients with COPD. The reliability, validity, advantages, limitations, and clinical applications of questionnaires, pedometers, and accelerometers are discussed. Finally, based on current published literature, we propose recommendations about which methods may be most useful in different research or clinical settings.

Changes in physical activity and all-cause mortality in COPD

Little is known about changes in physical activity in subjects with chronic obstructive pulmonary disease (COPD) and its impact on mortality. Therefore, we aimed to study changes in physical activity in subjects with and without COPD and the impact of physical activity on mortality risk.

Subjects from the Copenhagen City Heart Study with at least two consecutive examinations were selected. Each examination included a self-administered questionnaire and clinical examination.

1270 COPD subjects and 8734 subjects without COPD (forced expiratory volume in 1 s 67±18 and 91±15% predicted, respectively) were included. COPD subjects with moderate or high baseline physical activity who reported low physical activity level at follow-up had the highest hazard ratios of mortality (1.73 and 2.35, respectively; both p<0.001). In COPD subjects with low baseline physical activity, no differences were found in survival between unchanged or increased physical activity at follow-up. In addition, subjects without COPD with low physical activity at follow-up had the highest hazard ratio of mortality, irrespective of baseline physical activity level (p≤0.05).

A decline to low physical activity at follow-up was associated with an increased mortality risk in subjects with and without COPD. These observational data suggest that it is important to assess and encourage physical activity in the earliest stages of COPD in order to maintain a physical activity level that is as high as possible, as this is associated with better prognosis.

Association between peripheral muscle strength and daily physical activity in patients with COPD: a systematic literature review and meta-analysis

BACKGROUND

Patients with chronic obstructive pulmonary disease have skeletal muscle dysfunction and reduced daily physical activity (PA). Whether the reduction in quadriceps strength (QS) is directly linked to physical inactivity remains to be elucidated.

METHODS

A systematic review and a meta-analysis were conducted to determine the potential relationship between QS and the level of PA. The overall estimate of the correlation coefficient (r*) was calculated, and a subgroup analysis was conducted to analyze the association between QS and indices of PA separately.

RESULTS

A total of 8 studies were included in the meta-analysis. The overall association between QS and PA was low but highly significant (r * = 0.288, 95% CI = 0.180-0.389; P < .001). In the subgroup analysis, the association between QS and the number of steps per day was low (r = 0.260; 95% CI = 0.060-0.440) and the association between QS and the time spent walking was moderate (r = 0.418; 95% CI = 0.229-0.576).

CONCLUSIONS

Peripheral muscle strength is associated with PA as assessed by the number of steps per day and the time spent walking in patients with chronic obstructive pulmonary disease. The overall association between QS and PA was low to moderate and highly significant.