Inspiratory muscle training improves autonomic modulation and exercise tolerance in chronic obstructive pulmonary disease subjects: A randomized-controlled trial
Introduction
Chronic Obstructive Pulmonary Disease (COPD) is one of the leading causes of death worldwide (Halbert et al., 2006; Prince et al., 2015). Recent estimates point out that in 2020, COPD will be the third largest cause of death in the world (Ford et al., 2015). In addition, COPD is directly related to the development of autonomic imbalance, atherosclerosis and other cardiovascular complications (Mazzuco et al., 2015; van Gestel and Steier, 2010). Recent data have shown that cardiovascular diseases can be responsible for the greater number of hospitalizations, as well as 25% mortality in COPD subjects (Choudhury et al., 2014).
Among the variables affected, COPD causes autonomic dysfunction, as well as, reduced forced expiratory volume, decreases in oxygen consumption (VO2), low exercise tolerance and decreased respiratory muscle strength (Lacasse et al., 2005; Leidy et al., 2014). This fact contributes to a marked respiratory muscle desynchrony, accompanied by a fast and superficial respiratory pattern in certain activities such as tying a shoe, teeth brushing, etc (Stjepanovic et al., 2016). Also, the simple sustained elevation of the upper limbs in these subjects may lead to a significant increase in dyspnea sensation (Janaudis-Ferreira et al., 2014; Stjepanovic et al., 2016).
COPD subjects present a increased vagal autonomic modulation, as shown by other studies, mainly during the acute exacerbations (Kabbach et al., 2017). This increased vagal modulation might be one of the mechanisms responsible for the bronchoconstriction, so markedly present in COPD subjects (Audrit et al., 2017; Chong et al., 2017).
Other studies have already demonstrated the beneficial impacts of exercise training, such as running or strength exercises on autonomic modulation and exercise tolerance of COPD subjects (Borghi-Silva et al., 2009; Mohammed et al., 2016). Other exercises, such as inspiratory muscle training (IMT) in COPD subjects have been extensively described for its benefits in respiratory capacity and exercise tolerance (Dellweg et al., 2017; Montemezzo et al., 2014).
In addition, IMT has been shown as an effective strategy to improve cardiac autonomic control in hypertensive subjects and peripheral sympathetic activity in subjects with heart failure, increasing their functional capacity, the overall quality of life and cardiorespiratory fitness (Sin and Paul Man, 2003).
The heart rate variability (HRV) is a clinical tool used to measure the balance between sympathetic and parasympathetic (vagal) modulation through the data collection of the RR intervals. The reduction in the HRV has been associated with increased risk for cardiovascular disease and acute cardiac events, such as myocardial infarction (La Rovere et al., 1998; Thayer et al., 2010).
Since COPD subjects are at a higher risk of developing cardiovascular diseases (Chen et al., 2015; Sin and Paul Man, 2003) and have a marked vagal modulation (Janaudis-Ferreira et al., 2014), efficient strategies for reducing vagal-mediated bronchoconstriction, increasing respiratory capacities and, increasing exercise tolerance in this population are urgent. However, to this date, no study has ever investigated the effect of IMT on autonomic modulation of COPD subjects.
With this insight, the aim of this study was to evaluate the effect of IMT in respiratory function, exercise capacity, and, autonomic function in COPD subjects.
Section snippets
Trial design and study place
This was a single-center, randomized-controlled study, with balanced randomization (1:1 for two groups). The sample was composed of subjects with diagnosed with COPD recruited at the Pulmonary Rehabilitation Program between 2016 and 2017 at the Hospital Universitario Presidente Dutra, a reference center in Sao Luis, Brazil, the capital of Maranhão’state (Fig. 1). The control group received no intervention and was evaluated before and 12 weeks after. The IMT group received an intervention with
Overall characteristics
Table 1 shows the hemodynamic parameters, submaximal exercise capacity, peak oxygen consumption and body mass index (BMI) variables. All subjects were classified GOLD A class with grade I-II airflow obstruction. The subjects had a mean of 1.3 ± 0.4 exacerbations, but all with no hospital admissions in the last month before the protocol.
Respiratory function and Inspiratory muscle strength
No differences were found between control and IMT groups for FVC (liters and % of predicted), FEV1 (liters), FEV1/FVC, and FEF25/75 both in baseline period as
Discussion
This study aimed to evaluate the effect of 12 weeks of IMT at 30% of the maximum inspiratory pressure (PImax) on respiratory function, exercise capacity, and autonomic function in COPD subjects. The main finding of our study shows that a regular protocol of IMT was effective to improve maximal inspiratory and expiratory muscle strength, cardiac autonomic modulation and, functional capacity measured by the 6MWT in COPD subjects. However, the IMT protocol failed in show any improvements in
Conclusion
In conclusion, our study demonstrated that IMT at 30% of PImax for 12 weeks positively affected exercise capacity, PImax, PEmax and, autonomic function in a group of GOLD II COPD subjects.
Conflicts of interest
All authors declare no conflicts of interest.
Acknowledgments
We would like to thank the “Fundação de Amparo à Pesquisa do Estado do Maranhão (FAPEMA)” for its grant support for this research project and, the ‘Hospital Universitário Presidente Dutra’ for their open-mind policy for research. Cristiano Mostarda received grants from CNPq (Universal 442374/2014-3) and FAPEMA (Bolsa Produtividade and Universal 00358/15).
References (53)
- et al.
Evidence for exercise training in autonomic function modulation in patients with chronic obstructive pulmonary disease (COPD): a systematic review
Physiotherapy
(2016) - et al.
Do GOLD stages of COPD severity really correspond to differences in health status?
Eur. Respir. J.
(2003) - et al.
The nervous system of airways and its remodeling in inflammatory lung diseases
Cell Tissue Res.
(2017) - et al.
Reduced heart rate variability in patients with chronic obstructive pulmonary disease independent of anticholinergic or β-agonist medications
COPD
(2010) - et al.
Autonomic and cerebrovascular abnormalities in mild COPD are worsened by chronic smoking
Eur. Respir. J.
(2008) - et al.
Inspiratory muscle training and whole-body reconditioning in chronic obstructive pulmonary disease
Am. J. Respir. Crit. Care Med.
(1996) - et al.
Aerobic exercise training improves autonomic nervous control in patients with COPD
Respir. Med.
(2009) - et al.
Risk of cardiovascular comorbidity in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis
Lancet Respir. Med.
(2015) - et al.
Acute exacerbations of chronic obstructive pulmonary disease: causes and impacts
Indian J. Chest Dis. Allied Sci.
(2014) - et al.
The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: the JNC 7 report
JAMA\.
(2003)
Phosphodiesterase 4 inhibitors for chronic obstructive pulmonary disease
Cochrane Database Syst. Rev.
Comorbidities and systemic effects of chronic obstructive pulmonary disease
Clin. Chest Med.
Inspiratory muscle training in type 2 diabetes with inspiratory muscle weakness
Med. Sci. Sports Exerc.
Cardiovascular disease in patients with chronic obstructive pulmonary disease, Saskatchewan Canada: cardiovascular disease in COPD patients
Ann. Epidemiol.
Inspiratory muscle training in patients with heart failure and inspiratory muscle weakness: a randomized trial
J. Am. Coll. Cardiol.
Effects of inspiratory muscle training on cardiovascular autonomic control: A systematic review
Auton. Neurosci. Basic Clin.
Inspiratory muscle training during rehabilitation in successfully weaned hypercapnic patients with COPD
Respir. Med.
BP variability and cardiovascular autonomic function in relation to forced expiratory volume: a population-based study
Chest
Reference equations for the six-minute walk in healthy adults
Am. J. Respir. Crit. Care Med.
The six-minute walk test
Respir. Care
Effects of inspiratory muscle exercise in the pulmonary function, autonomic modulation, and hemodynamic variables in older women with metabolic syndrome
J. Exerc. Rehabil.
Inspiratory muscle training reduces blood pressure and sympathetic activity in hypertensive patients: a randomized controlled trial
Int. J. Cardiol.
Total and state-specific medical and absenteeism costs of COPD among adults aged ≥ 18 years in the United States for 2010 and projections through 2020
Chest
Applicability of a threshold loading device for inspiratory muscle testing and training in patients with COPD
Chest
Respiratory modulation of muscle sympathetic nerve activity in patients with chronic heart failure
Circulation
Heart rate variability and heart rate turbulence in patients with chronic obstructive pulmonary disease
Cardiol. J.
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