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

Meta-analysis of the impact of physical activity on the recovery of physical function in COVID-19 patients

Background

The decrease in physical function resulting from COVID-19 infection exerts a substantial negative influence on the quality of life of individuals. Physical activity plays a crucial and irreplaceable role in hastening the elimination of adverse effects on the body caused by acute and chronic diseases. Nevertheless, there have been reports of unfavorable events following physical activity post-COVID-19 infection, sparking debate regarding the efficacy of physical activity as a rehabilitation method to enhance the physical function of COVID-19 patients.

Objective

The aim of this study is to investigate the impact of physical activity on promoting the restoration of physical function among individuals with COVID-19, and to offer guidance for the advancement and consideration of physical activity in the rehabilitation treatment of COVID-19 patients.

Methods

A search was conducted on the PubMed and Web of Science core collection databases, with the search period set from January 1, 2020, to February 6, 2023. The included literature was assessed for risk of bias and methodological quality according to the Cochrane Handbook for Systematic Reviews of Interventions, utilizing Review Manager 5.1 software. The outcome measures from the included studies were analyzed, and the quality of evidence for the outcome measures was graded using the GRADE classification criteria.

Results

The effect of physical activity intervention on improving the 6-Minute Walk Test score in COVID-19 patients was better than that of conventional treatment [WMD = 69.19(95%CI = 39.38, 98.99), I2 = 57%(p = 0.03)]. The effect of physical activity on improving the 30-Second Sit-to-Stand Test score was better than that of conventional treatment [WMD = 2.98(95%CI = 1.91, 4.04), I2 = 0%(p = 0.56)]. There was no significant difference between physical activity and conventional treatment in improving Grip strength in COVID-19 patients [WMD = 2.35(95%CI = -0.49, 5.20), I2 = 0%(p = 0.80)]. The effect of physical activity on improving the Timed Up and Go test score in COVID-19 patients was better than that of conventional treatment [WMD = -1.16(95%CI = -1.98, -0.34), I2 = 4%(p = 0.35)]. The effect of physical activity on improving Forced Vital Capacity in COVID-19 patients was better than that of conventional treatment [WMD = 0.14(95%CI = 0.08, 0.21), I2 = 0%(p = 0.45)]. The effect of physical activity on improving Forced Expiratory Volume in the first second in COVID-19 patients was better than that of conventional treatment [WMD = 0.08(95%CI = 0.02, 0.15), I2 = 52%(p = 0.10)].

Conclusions

Physical activity plays a crucial role in facilitating the recovery of exercise capacity and pulmonary function in COVID-19 patients, helping to expedite the restoration of overall physical health. It is crucial for COVID-19 patients to undergo an accurate assessment of their physical condition before engaging in any physical activity.

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.

Mapping the global research landscape and hotspot of exercise therapy and chronic obstructive pulmonary disease: A bibliometric study based on the web of science database from 2011 to 2020

Background: The application of exercise therapy (ET) in chronic obstructive pulmonary disease (COPD) is generating increasing clinical efficacy and social-economic value. In this study, research trends, evolutionary processes and hot topics in this field are detailed, as well as predictions of future development directions.

Methods: Search for literature in the field of COPD and ET and analyze data to generate knowledge graphs using VOSiewer and CiteSpace software. The time frame for the search was from 2011 to January 2021. Then we extracted full-text key information (such as title, journal category, publication date, author, country and institution, abstract, and keyword) and obtained the co-citation analysis. Use hierarchal clustering analysis software developed by VOSviewer to map common citations, and use Citespace software to plot trend networks.

Results: The United States topped the list with 27.91% of the number of articles posted, followed by the UK at 25.44%. Imperial College London was the highest number of article publications in institutions, followed by Maastricht University and the University of Toronto. The Royal Brompton Harefield NHS Foundation Trust was one of many research institutions and currently holds the highest average citations per item (ACI) value, followed by Imperial College London and the University of Leuven. Judging from the number of publications related to ET and COPD, it is mainly published in cell biology, respiratory pulmonary diseases, and rehabilitation experiments study medicine. The European Respiration Journal is the most widely published in this field, followed by the International Journal of Chronic Obstructive Pulmonary Disease and Respiratory Medicine.

Conclusion: COPD combined with ET is widely used in clinical practice and is on the rise. A distinctive feature of the field is multidisciplinary integration. Rehabilitation research for COPD involves multidisciplinary collaboration, tissue engineering, and molecular biology mechanism studies to help patients remodel healthy breathing. Multidisciplinary rehabilitation measures provide a solid foundation for advancing clinical efficacy in the field of COPD.

Minimal important difference of two methods for assessment of quadriceps femoris strength post exercise program in individuals with COPD

BACKGROUND

The assessment of quadriceps femoris (QF) strength is recommended by international guidelines as an outcome of exercise training (ET) programs in patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To identify the minimal important difference (MID) of two methods for the assessment of improvement of QF strength after a high-intensity ET program in individuals with COPD: 1-repetition maximum (1RM) and maximal voluntary contraction (MVC).

METHODS

Individuals with moderate to very-severe stable COPD were submitted to high-intensity ET (3 days/week, 36 sessions). Lung function (spirometry), exercise capacity (6-minute walk test [6MWT]) and QF strength (1RM test and MVC by using a strain-gauge) were assessed before and after the ET program.

RESULTS

Twenty-one individuals were studied (65±8 years, BMI 27±6; FEV₁ 51±16%predicted). At the end of the ET program, QF strength improved significantly (10±4 Nm for MVC and 8 ± 6 kg for 1RM) (P<0.05 for both). The MID for improvement of the QF strength calculated by distribution-based methods ranged from 9.4 to 16 Nm (between 7.4% and 12.6% increase from baseline) for the MVC and from 2.5 to 3 kg (between 12% and 15% increase from baseline) for the 1RM test. Anchor-based MIDs could not be calculated since there was no correlation between the improvement of QF strength and the improvement of the proposed anchor (6MWT).

CONCLUSIONS

The MID for improvement of QF strength after a high-intensity ET program in individuals with moderate-to-severe stable COPD ranges between 9.4 and 16 Nm for the MVC assessed with a strain gauge and between 2.5 and 3 kg for the 1RM test.

Resistance Training before, during, and after COVID-19 Infection: What Have We Learned So Far?

At the end of 2019, a severe acute respiratory syndrome caused by SARS-CoV-2 started a pandemic, leading to millions of deaths and many important political and social changes. Even in the absence of contamination, the mobility reduction, social distancing and closing of exercise facilities negatively affected physical activity and conditioning, which is associated with muscle atrophy, loss of muscle strength, and reductions in functional capacity. In cases of infection, it has been shown that increased physical capacity is associated with decreased hospitalization and mortality risk. Although millions of people have died from COVID-19, most contaminated individuals survived the infection, but carried different sequelae, such as the severe loss of physical function and a reduced quality of life. Among different physical exercise models that might help to prevent and treat COVID-19-related conditions, resistance training (RT) might be particularly relevant. Among its benefits, RT can be adapted to be performed in many different situations, even with limited space and equipment, and is easily adapted to an individual's characteristics and health status. The current narrative review aims to provide insights into how RT can be used in different scenarios to counteract the negative effects of COVID-19. By doing this, the authors expect to provide insights to help deal with the current pandemic and similar events the world may face in the future.

Handgrip Strength in People With Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study was to systematically review the association between handgrip strength (HGS) and mortality, morbidity, and health-related quality of life (HRQL) in individuals with chronic obstructive pulmonary disease (COPD).

METHODS

The following databases were used: CENTRAL, CINAHL, EMBASE, MEDLINE Ovid, SPORTDiscus, and PsycINFO. Studies published between 2000 and 2020 in English, Portuguese, or French that examined the association of HGS with mortality, morbidity, and HRQL in individuals with stable COPD were selected. Two authors independently extracted data and assessed the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation framework. The study effects were pooled using random effects meta-analysis models after assessing heterogeneity. The search generated 710 studies, and 18 were included in the review. Studies evaluated a total of 12,046 individuals with stable COPD (mean percent of the predicted forced expiratory volume in 1 second = 34%-80%) using over 10 diverse protocols for HGS measurement. Statistically significant, small, and negative relationships were found between HGS and mortality (r = -0.03; 95% CI = -0.05 to -0.02). Independent of the outcome measure used to assess morbidity, the estimate of the overall relationship was small to moderate and negative: Body Mass Index, Airflow Obstruction, Dyspnea, and Exercise Index Updated (r = -0.42; 95% CI = -0.61 to -0.03); exacerbations (r = -0.02; 95% CI = -0.04 to -0.00); and hospitalizations (r = -0.69; 95% CI = -1.70 to 0.32). Similarly, for HRQL, independent of the outcome measure, the estimate of the overall relationship was small to fair and negative: COPD Assessment Test (weighted r = -0.22; 95% CI = -0.32 to -0.12), Chronic Respiratory Disease Questionnaire domains (-0.24 < r < -0.14), EuroQol Five-Dimension Questionnaire (utility score) (r = -0.17; 95% CI = -0.26 to -0.07), EuroQol Five-Dimension Questionnaire domains (-0.32 < r < -0.06), and St George Respiratory Questionnaire total (r = -0.26; 95% CI = -0.33 to -0.17). The quality of the evidence ranged from low to very low across outcomes.

CONCLUSION

Although heterogeneity was present among HGS measurement protocols, small to moderate associations were found, indicating that those with lower HGS have an increased likelihood of death, a higher risk of increased COPD morbidity (as assessed with Body Mass Index, Airflow Obstruction, Dyspnea and Exercise Capacity indexes), and poorer HRQL.

The association of objectively measured physical activity and sedentary behavior with skeletal muscle strength and muscle power in older adults: A systematic review and meta-analysis

BACKGROUND

Engaging in physical activity (PA) and avoiding sedentary behavior (SB) are important for healthy ageing with benefits including the mitigation of disability and mortality. Whether benefits extend to key determinants of disability and mortality, namely muscle strength and muscle power, is unclear.

AIMS

This systematic review aimed to describe the association of objective measures of PA and SB with measures of skeletal muscle strength and muscle power in community-dwelling older adults.

METHODS

Six databases were searched from their inception to June 21^st, 2020 for articles reporting associations between objectively measured PA and SB and upper body or lower body muscle strength or muscle power in community dwelling adults aged 60 years and older. An overview of associations was visualized by effect direction heat maps, standardized effect sizes were estimated with albatross plots and summarized in box plots. Articles reporting adjusted standardized regression coefficients (β) were included in meta-analyses.

RESULTS

A total of 112 articles were included representing 43,796 individuals (range: 21 to 3726 per article) with a mean or median age from 61.0 to 88.0 years (mean 56.4 % female). Higher PA measures and lower SB were associated with better upper body muscle strength (hand grip strength), upper body muscle power (arm curl), lower body muscle strength, and lower body muscle power (chair stand test). Median standardized effect sizes were consistently larger for measures of PA and SB with lower compared to upper body muscle strength and muscle power. The meta-analyses of adjusted β coefficients confirmed the associations between total PA (TPA), moderate-to-vigorous PA (MVPA) and light PA (LPA) with hand grip strength (β = 0.041, β = 0.057, and β = 0.070, respectively, all p ≤ 0.001), and TPA and MVPA with chair stand test (β = 0.199 and β = 0.211, respectively, all p ≤ 0.001).

CONCLUSIONS

Higher PA and lower SB are associated with greater skeletal muscle strength and muscle power, particularly with the chair stand test.

Practical Recommendations Relevant to the Use of Resistance Training for COVID-19 Survivors

The novel coronavirus disease (COVID-19) has emerged at the end of 2019 and caused a global pandemic. The disease predominantly affects the respiratory system; however, there is evidence that it is a multisystem disease that also impacts the cardiovascular system. Although the long-term consequences of COVID-19 are not well-known, evidence from similar diseases alerts for the possibility of long-term impaired physical function and reduced quality of life, especially in those requiring critical care. Therefore, rehabilitation strategies are needed to improve outcomes in COVID-19 survivors. Among the possible strategies, resistance training (RT) might be particularly interesting, since it has been shown to increase functional capacity both in acute and chronic respiratory conditions and in cardiac patients. The present article aims to propose evidence-based and practical suggestions for RT prescription for people who have been diagnosed with COVID-19 with a special focus on immune, respiratory, and cardiovascular systems. Based on the current literature, we present RT as a possible safe and feasible activity that can be time-efficient and easy to be implemented in different settings.

Reliability of quadriceps muscle power and explosive force, and relationship to physical function in people with chronic obstructive pulmonary disease: an observational prospective multicenter study

Background: Muscle power declines with age and is a stronger determinant of physical function than strength. Muscle power using computerized dynamometry has not been investigated in COPD.Objectives: To determine: 1) test-retest reliability of quadriceps power using a standardized protocol with computerized dynamometry; and 2) associations between quadriceps strength and power, and functional capacity.Design/Setting: Prospective observational study in four Canadian research labs.Participants: People with mild to very severe COPD.Methods: Tests were conducted on two days. Quadriceps muscle maximal strength was evaluated during a static maneuver using maximal voluntary isometric contractions (MVIC). Rate of torque development (RTD) during MVIC was used to assess explosive force. Muscle power was measured using a dynamic, isotonic protocol from which peak and average power and peak velocity were derived. Functional capacity was assessed with the Short Physical Performance Battery (SPPB). Reliability was assessed using intraclass correlation coefficients (ICC), standard error of measurements (SEM), and Bland Altman plots. Spearman and Pearson correlation coefficients were used for associations.Results: 65 patients (age 69 ± 8 years; FEV₁ 48 ± 21% of predicted) were included. ICC was 0.77 for RTD and 0.87-0.98 for isotonic power measures (95%CI 0.63-0.99, p < .001); SEM < 10% for average/peak power and peak velocity, and > 30% for RTD. SPPB had moderate correlation with average power, but not with MVIC or RTD.Conclusion: The standardized isotonic protocol with computerized dynamometry was reliable in assessing quadriceps power in COPD. Our data highlights that average power correlates best with functional capacity, indicating higher relevance than static measures when investigating determinants of function.

The efficacy of mindfulness-based interventions for patients with COPD: a systematic review and meta-analysis protocol

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease. It has adverse effects on patients' physical health, mental well-being and quality of life. The purpose of mindfulness-based interventions (MBIs) is to raise non-judgemental awareness and attention to current internal and external experiences. This means the attention is shifted from perceived and involuntary inner activities to current experience, keeping more curious, open and accepting attitudes towards current experience. Although some studies on the intervention effect of MBIs in patients with COPD have been conducted, the results are controversial, especially on dyspnoea, level of mindfulness and quality of life. Therefore, a systematic review of MBIs in patients with COPD is required to provide available evidence for further study.

METHODS AND ANALYSIS

In this study, different studies from various databases will be involved. Randomised controlled trials(RCTs)/quantitative studies, qualitative studies and case studies on the effect of MBIs in patients with COPD aged over 18 years will be included. We will search the literature in the databases of PubMed, Excepta Medica Base (EMBASE), Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Cochrane Library, PsycINFO and China National Knowledge Infrastructure(CNKI). The primary outcomes will include efficacy of MBIs for patients with COPD in terms of dyspnoea, depression and anxiety. The secondary outcomes will include efficacy of MBIs in terms of quality of life, mindful awareness, 6-minute walk test(6MWT) and nutritional risk index. Data extraction will be conducted by two researchers independently, and risk of bias of the meta-analysis will be evaluated based on the Cochrane Handbook for Systematic Reviews of Interventions. All data analysis will be conducted by data statistics software Review Manager V.5.3. and Stata V.12.0.

ETHICS AND DISSEMINATION

Since this study is a systematic review, the findings are based on the published evidence. Therefore, examination and agreement by the ethics committee are not required in this study. We intend to publish the study results in a journal or conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42018102323.

Effect and feasibility of non-linear periodized resistance training in people with COPD: study protocol for a randomized controlled trial

BACKGROUND

In people with chronic obstructive pulmonary disease (COPD), limb-muscle dysfunction is one of the most troublesome systemic manifestations of the disease, which at the functional level is evidenced by reduced strength and endurance of limb muscles. Improving limb-muscle function is an important therapeutic goal of COPD management, for which resistance training is recommended. However, current guidelines for resistance training in COPD mainly focus on improving muscle strength which only reflects one aspect of limb-muscle function and does not address the issue of reduced muscle endurance. The latter is of importance considering that the reduction in limb-muscle endurance often is greater than that of muscle weakness, and also, limb-muscle endurance seems to be closer related to walking capacity as well as arm function than to limb-muscle strength within this group of people. Thus, strategies targeting multiple aspects of the decreased muscle function are warranted to increase the possibility for an optimal effect for the individual patient. Periodized resistance training, which represents a planned variation of resistance training variables (i.e., volume, intensity, frequency, etc.), is one strategy that could be used to target limb-muscle strength as well as limb-muscle endurance within the same exercise regimen.

METHODS

This is an international, multicenter, randomized controlled trial comparing the effect and feasibility of non-linear periodized resistance training to traditional non-periodized resistance training in people with COPD. Primary outcomes are dynamic limb-muscle strength and endurance. Secondary outcomes include static limb-muscle strength and endurance, functional performance, quality of life, dyspnea, intramuscular adaptations as well as the proportion of responders. Feasibility of the training programs will be assessed and compared on attendance rate, duration, satisfaction, drop-outs as well as occurrence and severity of any adverse events.

DISCUSSION

The proposed trial will provide new knowledge to this research area by investigating and comparing the feasibility and effects of non-linear periodized resistance training compared to traditional non-periodized resistance training. If the former strategy produces larger physiological adaptations than non-periodized resistance training, this project may influence the prescription of resistance training in people with COPD.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT03518723 . Registered on 13 April 2018.

Ischiocrural Strength May Be a Better Prognostic Marker Than Quadriceps Strength in COPD

It is well known that chronic obstructive pulmonary disease (COPD) patients present with muscle dysfunction that may not correlate with the degree of severity of airflow obstruction. Historically, the strength deficit of the knee extensor musculature (quadriceps) has been described as an independent factor of mortality in COPD. We present the results of a retrospective study with longitudinal follow-up of 60 patients with severe COPD followed for 7 years. During follow-up 22 patients died, mainly of respiratory cause. We have observed that the strength of knee flexor muscles (ischiocrural) and dominant handgrip were independent predictors of mortality in severe COPD patients. However, knee extensor strength (quadriceps) was not an independent predictor of mortality. This is the first study which highlights the importance of knee flexor musculature as a prognostic factor in COPD.

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.

Changes in lower limb muscle function and muscle mass following exercise-based interventions in patients with chronic obstructive pulmonary disease: A review of the English-language literature

Chronic obstructive pulmonary disease (COPD) patients often experience lower limb muscle dysfunction and wasting. Exercise-based training has potential to improve muscle function and mass, but literature on this topic is extensive and heterogeneous including numerous interventions and outcome measures. This review uses a detailed systematic approach to investigate the effect of this wide range of exercise-based interventions on muscle function and mass. PUBMED and PEDro databases were searched. In all, 70 studies (n = 2504 COPD patients) that implemented an exercise-based intervention and reported muscle strength, endurance, or mass in clinically stable COPD patients were critically appraised. Aerobic and/or resistance training, high-intensity interval training, electrical or magnetic muscle stimulation, whole-body vibration, and water-based training were investigated. Muscle strength increased in 78%, muscle endurance in 92%, and muscle mass in 88% of the cases where that specific outcome was measured. Despite large heterogeneity in exercise-based interventions and outcome measures used, most exercise-based trials showed improvements in muscle strength, endurance, and mass in COPD patients. Which intervention(s) is (are) best for which subgroup of patients remains currently unknown. Furthermore, this literature review identifies gaps in the current knowledge and generates recommendations for future research to enhance our knowledge on exercise-based interventions in COPD patients.

Microvascular oxygen extraction during maximal isometric contraction in patients with chronic obstructive pulmonary disease

Abstract Introduction: COPD presents decrease in oxidative metabolism with possible losses of cardiovascular adjustments, suggesting slow kinetics microvascular oxygen during intense exercise. Objective: To test the hypothesis that chronic obstructive pulmonary disease (COPD) patients have lower muscle performance in physical exercise not dependent on central factors, but also greater muscle oxygen extraction, regardless of muscle mass. Methods: Cross-sectional study with 11 COPD patients and nine healthy subjects, male, paired for age. Spirometry and body composition by DEXA were evaluated. Muscular performance was assessed by maximal voluntary isometric contraction (MVIC) in isokinetic dynamometer and muscle oxygen extraction by the NIRS technique. Student t-test and Pearson correlation were applied. A significance level of p<0.05 was adopted. Results: Patients had moderate to severe COPD (FEV1 = 44.5 ± 9.6% predicted; SpO2 = 94.6 ± 1.6%). Lean leg mass was 8.3 ± 0.9 vs. 8.9 ± 1.0 kg (p =0.033), when comparing COPD and control patients, respectively. The decreased muscle oxygen saturation corrected by muscle mass was 53.2% higher (p=0.044) in the COPD group in MVIC-1 and 149.6% higher (p=0.006) in the MVIC-2. Microvascular extraction rate of oxygen corrected by muscle mass and total work was found to be 114.5% higher (p=0.043) in the COPD group in MVIC-1 and 210.5% higher (p=0.015) in the MVIC-2. Conclusion: COPD patients have low muscle performance and high oxygen extraction per muscle mass unit and per unit of work. The high oxygen extraction suggests that quantitative and qualitative mechanisms can be determinants of muscle performance in patients with COPD.

Adaptations in limb muscle function following pulmonary rehabilitation in patients with COPD - a review

Even though chronic obstructive pulmonary disease (COPD) is primarily a disease of the respiratory system, limb muscle dysfunction characterized by muscle weakness, reduced muscle endurance and higher muscle fatigability, is a common secondary consequence and a major systemic manifestation of the disease. Muscle dysfunction is especially relevant in COPD because it is related to important clinical outcomes such as mortality, quality of life and exercise intolerance, independently of lung function impairment. Thus, improving muscle function is considered an important therapeutic goal in COPD management. Pulmonary rehabilitation (PR) is a multidisciplinary, evidence-based and comprehensive approach used to promote better self-management of the disease, minimize symptom burden, optimize functional status, and increase participation in activities of daily life. Exercise training, including cardiovascular and muscle exercises, is the cornerstone of PR and is considered the best available strategy to improve exercise tolerance and muscle function among patients with COPD. This paper addresses the various components of exercise training within PR used to improve limb muscle function in COPD, providing clinicians and health-care professionals with an overview and description of these various exercise modalities and of their effects on limb muscle function. Guidance and recommendations to help design optimal limb muscle training regimens for these patients are also presented.

Relationship between balance and physical activity measured by an activity monitor in elderly COPD patients

Background

Little is known regarding the relationship between balance impairments and physical activity in COPD. There has been no study investigating the relationship between balance and objectively measured physical activity. Here we investigated the association between balance and physical activity measured by an activity monitor in elderly COPD patients.

Materials and methods

Twenty-two outpatients with COPD (mean age, 72±7 years; forced expiratory volume in 1 second, 53%±21% predicted) and 13 age-matched healthy control subjects (mean age, 72±6 years) participated in the study. We assessed all 35 subjects’ balance (one-leg standing test [OLST] times, Short Physical Performance Battery total scores, standing balance test scores, 4 m gait speed, and five-times sit-to-stand test [5STST]) and physical activity (daily steps and time spent in moderate-to-vigorous physical activity per day [MV-PA]). Possible confounders were assessed in the COPD group. The between-group differences in balance test scores and physical activity were analyzed. A correlation analysis and multivariate regression analysis were conducted in the COPD group.

Results

The COPD patients exhibited significant reductions in OLST times (P=0.033), Short Physical Performance Battery scores (P=0.013), 4 m gait speed (P<0.001), five-times sit-to-stand times (P=0.002), daily steps (P=0.003), and MV-PA (P=0.022) compared to the controls; the exception was the standing balance test scores. The correlation and multivariate regression analyses revealed significant independent associations between OLST times and daily steps (P<0.001) and between OLST times and MV-PA (P=0.014) in the COPD group after adjusting for possible confounding factors.

Conclusion

Impairments in balance and reductions in physical activity were observed in the COPD group. Deficits in balance are independently associated with physical inactivity.

Why and How Limb Muscle Mass and Function Should Be Measured in Patients with Chronic Obstructive Pulmonary Disease

Impaired limb muscle function is a common occurrence in patients with chronic obstructive pulmonary disease (COPD), and it negatively influences exercise tolerance, quality of life, and even survival. Assessment of limb muscle mass and function in COPD is highly encouraged; it should include the quadriceps muscle, but other lower and upper limb muscles may also be evaluated to provide valuable information. Quantification of muscle mass as well as assessment of muscle strength and endurance are suggested. Bioelectrical impedance and dual-energy X-ray absorption can be realistically used in the clinical environment to monitor body composition. Although sophisticated computerized dynamometers provide the most accurate assessment, simple exercise and testing equipment are valid alternatives and they should help in implementing limb muscle function assessment in clinical settings. Isometric measurements, using strain-gauges or hand-held dynamometers, should be favored for their simplicity, availability, and quality of information provided. This perspective provides a rationale for the evaluation of limb muscle mass and function in COPD in routine clinical practice. In addition, measurement techniques used to assess limb muscle mass, strength, endurance, and fatigue in various clinical settings are discussed.

Activity limitation and exertional dyspnea in adult asthmatic patients: What do we know?

Limitation of activity is the most cited symptom described by uncontrolled asthma patients. Assessment of activity limitation can be undertaken through several ways, more or less complex, subjective or objective. Yet little is known about the link between patients sensations and objective measurements. The present review reports the current knowledge regarding activity limitation and symptom perception (i.e., exertional dyspnea) in adult patients with asthma. This work is based on references indexed by PubMed, irrespective of the year of publication. Overall, patients with stable asthma do not have a more sedentary lifestyle than healthy subjects. However, during a cycle ergometric test, the maximal load is reduced when FEV1, FVC and muscle strengths are decreased. Additionally, during the six-minute walking test, mild asthma patients walk less than healthy subjects even if the minimal clinically important difference is not reached. The major complaint of asthma patients when exercising is dyspnea that is mainly related to the inspiratory effort and also to dynamic hyperinflation in some circumstances. Finally, the administration of bronchodilator does not improve the ventilatory pattern and the exercise capacity of asthma patients and little is known on its effect on exertional dyspnea. The present review allows to conclude that until now there is no gold standard test allowing the objective assessment of "activity limitation and exertional dyspnea" in asthma patients.

Changes in structural and metabolic muscle characteristics following exercise-based interventions in patients with COPD: a systematic review

Patients with COPD suffer from lower-limb muscle dysfunction characterized by lower muscle oxidative capacity and muscle mass. Exercise-based training is expected to attenuate lower-limb intramuscular characteristics, but a detailed systematic approach to review the available evidence has not been performed yet. PUBMED and PEDro databases were searched. Twenty-five studies that implemented an exercise-based training program (aerobic and/or resistance training, high intensity interval training, electrical or magnetic stimulation) and reported muscle biopsy data of patients with COPD were critically appraised. The coverage of results includes changes in muscle structure, muscle protein turnover regulation, mitochondrial enzyme activity, oxidative and nitrosative stress, and inflammation after exercise-based training interventions. Study design and training modalities varied among studies, which partly explains the observed heterogeneous response in muscle characteristics. Gaps in the current knowledge are identified and recommendations for future research are made to enhance our knowledge on exercise training effects in patients with COPD.