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JEPonline
Effects of Physical Exercise on an Amazonian Population with Chronic Obstructive Pulmonary Disease in Autonomic Heart Rate Modulation
Rodrigo Rocha1,2,3, Edivânia Silva3, Jairo Conceição 3, Larissa Rocha 3, Saul Carneiro4, Marlene A. Moreno1
1Postgraduate Program of Sciences of Human Movement of Methodist University of Piracicaba, São Paulo, Brazil, 2Department of Sciences of Human Movement of State University of Pará, Pará, Brazil, 3School of Physiotherapy of Amazon University, Pará, Brazil 4University Hospital João de Barros Barreto/Federal University of Pará, Pará, Brazil
ABSTRACT
Rocha R, Silva E, Conceição J, Rocha L, Carneiro S, Moreno M.
Effects of Physical Exercise on an Amazonian Population with Chronic Obstructive Pulmonary Disease in Autonomic Heart Rate Modulation. JEPonline 2017;20(3):156-167. The aim of this study was to verify the effect of an exercise protocol on the autonomic modulation of the heart rate of individuals with chronic obstructive pulmonary disease. Thirty-three of the initial 38 subjects with chronic obstructive pulmonary disease (COPD) completed the study. Heart rate variability (HRV) was evaluated using the POLAR® monitor. All subjects performed aerobic physical training and muscle strengthening. Rehabilitation occurred for 8 wks with 2 sessions·wk-1 lasting 50 min each. The variables in time domain (R-R interval, SDNN, RMSSD, and TINN), in frequency domain (LF, HF, and LF/HF), and nonlinear variables (SD1, SD2, Shannon Entropy, and Determinism) were analyzed. The findings indicate that in the frequency domain of variability, no variables were statistically significant. However, the RMSSD, SD1, and SD2 indices presented significant results after pulmonary rehabilitation, which positively influenced the autonomic modulation of the heart rate of COPD patients.
Key Words: Autonomic Nervous System, Chronic Obstructive Pulmonary Disease, Rehabilitation
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INTRODUCTION
Chronic obstructive pulmonary disease (COPD) is due to an inflammatory response that leads to respiratory muscle dysfunction that plays a key role in gas exchange abnormalities. It is associated with smoking and/or exposure to harmful airways (16). In the Brazilian Amazon, the effects of biomass burning on lung function and the development of respiratory diseases is still a relatively new area of study (34). However, it is clear that individuals with COPD have reduced peak expiratory flow, which is a condition that is also associated with quality of air (35) and living in cities around the arch of deforestation (such as Belém-Pará) (8).
Among the symptoms of COPD are dyspnea, nutritional changes, decreased strength of the muscular system (especially the muscles involved in respiratory function), low exercise capacity due to the muscle weakness and fatigue, and pulmonary hyperinflation (12), which may also be related to the alteration of autonomic heart rate modulation. One or more of these conditions will reduce the physical conditioning of the COPD population, making pulmonary rehabilitation essential in these patients (23) to help avoid the increased risk for repeated hospital admissions (33).
Pulmonary rehabilitation protocols tend to improve the COPD patient’s response to physical exercise and barroreflex performance. In addition, the rehabilitation protocols help to improve the patient’s autonomic heart rate modulation from the attenuation of dyspnea. The overall result is that the improvements help to produce a better chest mobilization with a positive influence on the sympathetic nervous system (31).
Patients with COPD have chronic characteristics that lead to several impairments in their autonomic function and intolerance to physical activities (14). Thus, the purpose of the present study was to verify the effect of a pulmonary rehabilitation with an exercise protocol on the autonomic modulation of the heart rate of individuals with COPD in Brazilian Amazon.
METHODS
Subjects
This study consisted of 38 volunteers with a clinical diagnosis of severe and very severe COPD. All subjects met the inclusion criteria to participate in this study. Volunteers with deformities, hemodynamic instability, cardiovascular diseases, uncontrolled hypertension, and beta pacemakers, and those who were diagnosed with associated diseases that could interfere with cardiac autonomic control or impede exercise tolerance were not considered for this study.
The study was conducted in the physiotherapy outpatient clinic of the University Hospital João de Barros Barreto between January 2016 and February 2017. The research was approved by the Research Ethics Committee of the University Hospital João de Barros Barreto under the number of opinion 1.322.578, with clinical trial registration in the Clinical Trials NCT02783326, as well as the agreement and signing of the Informed Consent Form by the volunteers before starting the study.
Procedures
All subjects had the same clinical prognosis with a similar degree of pulmonary dysfunction. It was an experimental and non-randomized clinical study that used physical training according to the criteria established by the Global Initiative for Chronic Obstructive Pulmonary Disease (GOLD) (14). Rehabilitation (i.e., aerobic training, muscle strengthening, and stretching of the involved muscles) was 8 wks in duration with 2 sessions·wk-1 for ~50 min each session.
During each pulmonary rehabilitation session, the patients engaged in 20 min of aerobic training on a treadmill and/or exercise bicycle with a modified Borg effort perception scale at a tolerable intensity level of 4. Then, the patients worked on increasing muscle strength of their upper limbs using dumbbells, elastic bands, and open and closed kinetic chains exercises. Each session ended with the patients doing active stretching exercises.
Strength training consisted of 3 sets of 10 repetitions for each exercise. The load imposed was 1 kg for each subject to which the subject performed movements of diagonal upper limbs, as well as flexion and extension of the lower limb, adding 1 kg every 1 min until maximum effort was achieved. The strength treatment consisted of 50% of the maximum load of which the test was repeating every 2 wks for progression of the load.
The evaluation of heart rate variability (HRV) was performed one day before the start of the pulmonary rehabilitation protocol and 24 hrs at the end of the protocol to avoid the influence of physical exercise on the autonomic frequency modulation of the heart (11). The VFC was captured by means of a frequency meter of the POLAR® brand, model RS800cx. The heart rate signal was captured by a strap placed on the subjects’ chest at the xiphoid process while lying supine for 10 min. Subjects were instructed to maintain a normal breathing pattern. No talking was permitted so that the heart rate did not change. The data were transferred to a researcher who was not involved in the present study. The researcher transferred the data to the Polar®ProTrainer Software through an infrared signal transmission interface, which transformed into .txt text format so that it could be analyzed by a mathematical routine in the Kubios® HRV2.2 program to obtain each subject’s heart rate variability. Then, the data were tabulated in the Excell program to perform the statistical analysis. All subjects were identified by codes.
Statistical Analyses
The BioEstat® 5.2 application was used for statistical analysis. The Shapiro-Wilk test was used to verify the distribution of the data. The Student's t-test was used for the analysis of significance. For the nominal variables, the Binominal test was used. Statistical significance was set at an alpha level of P<0.05. The data are presented as mean and standard deviation.
RESULTS
Thirty-eight subjects (27 males and 11 females) with a mean age 67.94 ± 8.49 yrs were initially enrolled in the study. However, due to different reasons, 33 subjects with COPD completed the study. The flowchart of the study volunteers is shown in Figure 1. The demographic and clinical data are presented in Table 1 and Table 2.
Figure 1. Participation Flowchart of the Subjects in the Study.
Table 1 presents the mean values and standard deviations of the subjects’ age, body mass index (BMI), and forced expiratory volume in the first second (FEV1). Blood pressure (systolic and diastolic pressures), respiratory rate (RF), and frequency (HR) at rest before and after the application of pulmonary rehabilitation protocol were also measured, but are not presented in the Table.
Table 1. Demographic and Clinical Characteristics of the Subjects with Values Expressed as Means and Standard Deviations.
Categories / Mean ± SDAge / 68.46 ± 8.27
BMI (kg·m-²) / 21.90 ± 3.68
FEV1 / 4.67 ± 11.79
BMI = body mass index; FEV1 = Forced expiratory volume in the first second
Table 2 shows that ~80% of the subjects were smokers, and that the minority (i.e., 15.3%) needed oxygen supplementation in the treatment, as well as the predominance of subjects in the severe stage of COPD. In addition, the drugs bromide tiotropium (a long acting, 24-hr anticholinergic bronchodilator), salmeterol xinafoate (used with other medicines to treat bronchospasms), and fluticasone propianate (an oral inhaler used to manage asthma) were the most commonly used by the subjects, with more than 50% of the sample using additional drugs concomitant with them.
Table 2. Clinical Characteristics of Subjects.
Variables / Subject PercentageStage of Disease
Severe / 84.6
Very severe / 15.4
Drugs
Bromide Tiotropium / 84.6
Salmeterol Xinafoate / 76.9
Fluticasone Propionate / 53.8
Smoking
Yes / 76.9
No / 23.1
Oxygen Therapy
Yes / 15.3
No / 84.7
Comorbidities
Hypertension
Diabetes Mellitus / 53.8
7.6
As shown in Table 3, in regards to the linear variables in the time domain, only the RMSSD index was significant (P≤0.05). In the frequency domain, no significant variable was found. Regarding the nonlinear indices, the dispersion of points perpendicular to the line of identity (SD1) and the dispersion of points along the line of identity (SD2) presented significant results.
Table 3. Analysis of Pre- and Post-Pulmonary Rehabilitation Variables with Values Expressed as Means and Standard Deviations.
Variables / Pre-Program / Post-Program / P ValueRR (ms) / 786.3 ± 130.74 / 761.10 ± 129.56 / 0.0653
SDNN (ms) / 27.03 ± 15.28 / 24.43 ± 14.39 / 0.0555
RMSSD (ms) / 19.90 ± 15.09 / 20.76 ± 20.70 / 0.0095*
TINN (ms) / 135 ± 85.07 / 114.61 ± 64.14 / 0.0989
LF (nu) / 63.73 ± 25.45 / 54.79 ± 25.82 / 0.1390
HF (nu) / 36.26 ± 25.45 / 45.20 ± 25.82 / 0.1425
LF/HF / 3.8 ± 4.0 / 2.2 ± 3.1 / 0.1731
SD1 (ms) / 14.13 ± 10.71 / 14,76 ± 14.75 / 0.0031*
SD2 (ms) / 36.34 ± 20.67 / 30.98 ± 16.76 / 0.0032*
Det (%) / 97.83 ± 1.75 / 97.84 ± 1.48 / 0.0896
SE / 3.1 ± 3.02 / 3.1 ± 3.2 / 0.1815
RR = R-R interval (R-Ri); SDNN = Standard deviation of the mean of the normal iR-R; RMSSD = Square root of the mean square of the differences between consecutive iR-Rs; TINN = Triangular interpolation of RR intervals; LF = Low frequency; HF = High Frequency; LF/HF = Ratio between low frequency and high frequency; SD1 = Dispersion of points perpendicular to the line of identity; SD2 = Dispersion of points along the identity line; Det = Determinism; SE = Entropy Shannon; Normalized Units (nu); Milliseconds (ms). *P≤0.05
DISCUSSION
The purpose of this study was to evaluate the effects of exercise in patients with COPD on cardiac autonomic modulation. A number of studies have tested the effects of exercise on heart rate variability in COPD (15,32), but none has tested in Amazonian population with COPD.
The demographic characteristics presented by Handa et al. (15) and Vasiliki et al. (32) indicate the prevalence of males with COPD. Also, the data presented by Azambuja et al. (2) report that active smoking is the primary cause of the disease. This is a pathology that first affected the male gender, reflecting the increase in the mortality rate among men. However, it is important to point out that women may be more susceptible to cigarette smoke and more likely to develop COPD than previously realized. In the United States,COPD in womenis actually higher in every age group except for people older than 74, which is in contrast to Brazil.
The subjects in the present study were classified as having low body weight, which is in agreement with the BMI analysis as reported by Costa et al. (10). They explained that patients with COPD usually present changes in their body composition that are associated the loss of lean muscle mass, the presence of sarcopenia, and physical intolerance to exercise and daily physical activities. In addition to the subjects’ mean age of 68 yrs and no regular exercise, the physiological deterioration (18) may explain why the subjects struggled to perform everyday activities such as walking and performing basic self-care. Also, for these reasons, there is an increase in the risk of mortality in people with COPD.
The prevalence of smokers in the present sample is notorious, since smoking is indicated as the main risk factor for COPD (27). However, this pathology may also occur by genetic etiology, such as alpha-1-antitrypsin deficiency; whereas it is responsible for the regulation of elastase synthesis that plays a protective role in the lungs in the presence of inflammation or irritants (16). This may explain the presence of non-smokers with a diagnosis of COPD in the present study.
Regarding the presence of comorbidities, studies have demonstrated a strong relationship between the metabolic syndrome and COPD. This indicates that such an association may be due to the continuous inflammatory response presented in COPD, where in response to inflammatory changes the immune system ends up performing metabolic compensations that may lead to hyperlipidemia and increased gluconeogenesis that predisposes an individual to cardiovascular alterations or even diabetes mellitus (1,34).
It is noteworthy that 53.8% of subjects in this study had high blood pressure. The presence of this comorbidity is not uncommon among COPD patients, which is in agreement with the findings of Simonovska et al. (27). Mazzocchi et al. (19) when analyzing the behavior of the physiological variables of the COPD patients submitted to a walking test of 6 min followed by a ladder test to verify that the patients’ HR change occurs due to the variation of load during the rehabilitation protocol. Lung damage from the disease causes the heart to work harder to send blood and oxygen to the musculature.
According to GOLD (14), drug therapy is an important treatment in the different stages of COPD. In fact, in the present study, 84.6% of the subjects were taking bromide triotropium. Baker et al. (3), it is associated with a decrease in the occurrence of exacerbation of the disease when compared to placebos. Approximately 77% of the subjects were taking salmeterol xinafoate and ~54% were taking fluticasone propionate; both medications help to decrease the number of deaths from COPD (26).