The major limitation to exercise performance in COPD is inadequate energy supply to the respiratory and locomotor muscles vs. lower limb muscle dysfunction vs. dynamic hyperinflation

Association of peak expiratory flow with motoric cognitive risk syndrome among older adults

Background

The association between lung function and motoric cognitive risk syndrome (MCR) is unclear. We aimed to explore the association of peak expiratory flow (PEF) with MCR using cross-sectional and longitudinal analyses.

Methods

Within the CHARLS, 5095 participants were included in the cross-sectional analysis, and 4340 MCR-free participants were included in the longitudinal analysis. The PEF was assessed with a lung peak flow meter. MCR was characterized by cognitive complaints and a slow walking speed with normal mobility and without dementia. Logistic regression, Cox regression, and Laplace regression models were employed for data analysis.

Results

In this cross-sectional study, logistic regression analyses revealed that continuous PEF was associated with MCR (odds ratio [OR], 0.998; 95% confidence interval [CI], 0.998, 0.999), and the ORs (95% CIs) of MCR prevalence were 0.857 (0.693, 1.061) for the middle tertile and 0.665 (0.524, 0.845) for the highest tertile compared to the lowest tertile. In a longitudinal cohort study, continuous PEF was dose-dependently associated with the risk of MCR. Compared with those in the lowest tertile of PEF, the hazard ratios (95% CIs) of incident MCR were 0.827 (0.661, 1,036) for the middle tertile and 0.576 (0.432, 0.767) for the highest tertile. Furthermore, compared with the lowest tertile, the highest tertile was associated with a delayed onset time of MCR of 0.484 (95% CI: 0.151, 0.817) years.

Conclusion

A higher PEF was related to a lower prevalence of MCR and a lower risk for MCR, and a higher PEF also prolonged the onset time of MCR.

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.

Physical activity associates with disease characteristics of severe asthma, bronchiectasis and COPD

BACKGROUND AND OBJECTIVE

Physical activity (PA) in obstructive airway diseases (OAD) is likely to be impaired but this has not been extensively studied outside of chronic obstructive pulmonary disease (COPD). We describe PA levels in severe asthma and bronchiectasis compared to moderate-severe COPD and to controls, and tested the cross-sectional associations of PA (steps/day) with shared disease characteristics in the OAD group.

METHODS

Adults with OAD (severe asthma = 62, COPD = 67, bronchiectasis = 60) and controls (n = 63) underwent a multidimensional assessment, including device-measured PA levels.

RESULTS

The OAD group included 189 participants (58.7% females), with median (interquartile range) age of 67 (58-72) years and mean forced expiratory volume in the first second (FEV₁ ) % predicted of 69.4%. Demographic characteristics differed between groups. Compared to controls (52.4% females, aged 55 (34-64) years, median 7640 steps/day), those with severe asthma, bronchiectasis and COPD accumulated less steps/day: median difference of -2255, -2289, and -4782, respectively (P ≤ 0.001). Compared to COPD, severe asthma and bronchiectasis participants accumulated more steps/day: median difference of 2375 and 2341, respectively (P ≤ 0.001). No significant differences were found between the severe asthma and bronchiectasis group. Exercise capacity, FEV₁ % predicted, dyspnoea and systemic inflammation differed between groups, but were each significantly associated with steps/day in OAD. In the multivariable model adjusted for all disease characteristics, exercise capacity and FEV₁ % predicted remained significantly associated.

CONCLUSION

PA impairment is common in OAD. The activity level was associated with shared characteristics of these diseases. Interventions to improve PA should be multifactorial and consider the level of impairment and the associated characteristics.

High oxygen extraction and slow recovery of muscle deoxygenation kinetics after neuromuscular electrical stimulation in COPD patients

PURPOSE

It was hypothesized that patients with chronic obstructive pulmonary disease (COPD) would exhibit a slow muscle deoxygenation (HHb) recovery time when compared with sedentary controls.

METHODS

Neuromuscular electrical stimulation (NMES 40 and 50 mA, 50 Hz, 400 µs) was employed to induce isometric contraction of the quadriceps. Microvascular oxygen extraction (µO2EF) and HHb were estimated by near-infrared spectroscopy (NIRS). Recovery kinetic was characterized by measuring the time constant Tau (HHb-τ). Torque and work were measured by isokinetic dynamometry in 13 non-hypoxaemic patients with moderate-to-severe COPD [SpO2 = 94.1 ± 1.6 %; FEV1 (% predict) 48.0 ± 9.6; GOLD II-III] and 13 age- and sex-matched sedentary controls.

RESULTS

There was no desaturation in either group during NMES. Torque and work were reduced in COPD versus control for 40 and 50 mA [torque (Nm) 50 mA = 28.9 ± 6.9 vs 46.1 ± 14.2; work (J) 50 mA = 437.2 ± 130.0 vs. 608.3 ± 136.8; P < 0.05 for all]. High µO2EF values were observed in the COPD group at both NMES intensities (corrected by muscle mass 50 mA = 6.18 ± 1.1 vs. 4.68 ± 1.0 %/kg; corrected by work 50 mA = 0.12 ± 0.05 vs. 0.07 ± 0.02 %/J; P < 0.05 for all). Absolute values of HHb-τ (50 mA = 31.11 ± 9.27 vs. 18.08 ± 10.70 s), corrected for muscle mass (50 mA 3.80 ± 1.28 vs. 2.05 ± 1.45 s/kg) and corrected for work (50 mA = 0.08 ± 0.04 vs. 0.03 ± 0.02 s/J) were reduced in COPD (P < 0.05 for all). The variables behaviour for 40 mA was similar to those of 50 mA.

CONCLUSIONS

COPD patients exhibited a slower muscle deoxygenation recovery time after NMES. The absence of desaturation, low torque and work, high µO2EF and high values for recovery time corrected by muscle mass and work suggest that intrinsic muscle dysfunction has an impact on muscle recovery capacity.

Autonomic dysfunction in patients with chronic obstructive pulmonary disease (COPD)

It has been recognized that chronic obstructive pulmonary disease (COPD) is a systemic disease which has been shown to negatively affect the cardiovascular and autonomic nerve system. The complexity of the physiologic basis by which autonomic dysfunction occurs in patients with COPD is considerable and the knowledge in this field remains elementary. The purpose of this review is to provide an overview of important potential mechanisms which might affect the autonomic nervous system in patients with COPD. This review aims to summarize the basic research in the field of autonomic dysfunction in patients with COPD. In COPD patients the activity of sympathetic nerves may be affected by recurrent hypoxemia, hypercapnia, increased intrathoracic pressure swings due to airway obstruction, increased respiratory effort, systemic inflammation and the use of betasympathomimetics. Furthermore, experimental findings suggest that autonomic dysfunction characterized by a predominance of sympathetic activity can significantly modulate further inflammatory reactions. The exact relationship between autonomic dysfunction and health status in COPD remains to be elucidated. Treatment aimed to restore the sympathovagal balance towards a reduction of resting sympathetic activity may modulate the inflammatory state, and possibly contributes to improved health status in COPD.

Addition of tiotropium to formoterol improves inspiratory muscle strength after exercise in COPD

BACKGROUND

The addition of tiotropium bromide (TIO) to formoterol fumarate (FOR) improves exercise performance in patients with chronic obstructive pulmonary disease (COPD). In this study, we test the hypothesis that the addition of TIO to FOR may improve respiratory muscle performance and oxygen uptake kinetics after exercise in patients with COPD.

METHODS

Thirty eight patients with COPD were randomized to a 2 week treatment with FOR 12 μg twice a day plus TIO 18 μg once a day (FOR + TIO) or FOR 12 μg twice a day plus placebo (FOR + PLA) once a day, using a double-blind crossover design. Inspiratory muscle. Strength was measured before, immediately after, as well as 2, 5, and 10 min during recovery of exercise. Time to limit of tolerance on a constant work load exercise test and oxygen uptake kinetics during recovery were evaluated before and after intervention.

RESULTS

Only FOR + TIO improved resting (63 ± 10 cm to 84 ± 11 cmH(2)O) and post-exercise (49 ± 7 cm to 84 ± 11 cmH(2)O) maximal inspiratory pressure. Time to limit of tolerance on the constant work load test was increased by FOR + PLA and by FOR + TIO, but the size of the increment was significantly larger with FOR + TIO (40.7 ± 7.6% vs. 84.5 ± 8.2%; p < 0.05). Only FOR + TIO improved oxygen uptake kinetics during recovery (69 ± 21 to 60 ± 18 s). The improvement in maximal inspiratory pressure (0.78, p < 0.001) and in oxygen uptake kinetics (-0.91, p < 0.001) correlated with the change in time to the limit of tolerance.

CONCLUSIONS

The addition of TIO to FOR improves inspiratory muscle strength and oxygen uptake kinetics after exercise in COPD patients.

Effect of pulmonary rehabilitation on peripheral muscle fiber remodeling in patients with COPD in GOLD stages II to IV

BACKGROUND

In most patients with COPD, rehabilitative exercise training partially reverses the morphologic and structural abnormalities of peripheral muscle fibers. However, whether the degree of improvement in muscle fiber morphology and typology with exercise training varies depending on disease severity remains unknown.

METHODS

Forty-six clinically stable patients with COPD classified by GOLD (Global Initiative for Obstructive Lung Disease) as stage II (n = 14), III (n = 18), and IV (n = 14) completed a 10-week comprehensive pulmonary rehabilitation program consisting of high-intensity exercise three times weekly.

RESULTS

At baseline, muscle fiber mean cross-sectional area and capillary density did not significantly differ between patients with COPD and healthy control subjects, whereas muscle fiber type I and II proportion was respectively lower (P < .001) and higher (P < .002) in patients with GOLD stage IV compared with healthy subjects and patients with GOLD stages II and III. Exercise training improved, to a comparable degree, functional capacity and the St. George Respiratory Questionnaire health-related quality of life score across all three GOLD stages. Vastus lateralis muscle fiber mean cross-sectional area was increased (P < .001) in all patient groups (stage II: from 4,507 ± 280 μm² to 5,091 ± 271 μm² [14% ± 3%]; stage III: from 3,753 ± 258 μm² to 4,212 ± 268 μm² [14% ± 3%]; stage IV: from 3,961 ± 266 μm² to 4,551 ± 262 μm² [17% ± 5%]), whereas all groups exhibited a comparable reduction (P < .001) in type IIb fiber proportion (stage II: by 6% ± 2%; stage III: by 6% ± 1%; stage IV: by 7% ± 1%) and an increase (P < .001) in capillary to fiber ratio (stage II: from 1.48 ± 0.10 to 1.81 ± 0.10 [23% ± 5%]; stage III: from 1.29 ± 0.06 to 1.56 ± 0.09 [21% ± 5%]; stage IV: from 1.43 ± 0.10 to 1.71 ± 0.13 [18 ± 3%]). The magnitude of changes in the aforementioned variables did not differ across GOLD stages.

CONCLUSIONS

Functional capacity and morphologic and typologic adaptations to rehabilitation in peripheral muscle fibers were similar across GOLD stages II to IV. Pulmonary rehabilitation should be implemented in patients at all COPD stages.

Exercise intolerance in cancer and the role of exercise therapy to reverse dysfunction

Exercise tolerance reflects the integrative capacity of components in the oxygen cascade to supply adequate oxygen for ATP resynthesis. Conventional cancer therapies can simultaneously affect one or more components of this cascade and reduce the body's ability to deliver or utilise oxygen and substrate, leading to exercise intolerance. We propose that molecularly-targeted therapy is associated with a further, more subtle, negative effect on the components that regulate exercise limitation. We outline possible causes of exercise intolerance in patients with cancer and the role of exercise therapy to mitigate or prevent dysfunction. We also discuss possible implications for exercise-regulated gene expression for cancer biology and treatment efficacy. A better understanding of these issues might lead to more effective integration of exercise therapy to optimise the treatment and management of patients with cancer.