Influence of the resistance training on heart rate ...

EUR J PHYS REHABIL MED 2013;49:1-9

Influence of the resistance training on heart rate variability, functional capacity and muscle strength in the chronic obstructive pulmonary disease A. L. RICCI-VITOR ¹, R. BONFIM ¹, L. C. FOSCO ¹, G. N. BERTOLINI ¹ E. M. C. RAMOS ¹, D. RAMOS ¹, C. M. PASTRE ¹, M. GODOY ², L. C. M. VANDERLEI ¹

Background. The chronic obstructive pulmonary disease (COPD) is associated with the strength and resistance decreasing in addition to the dysfunction on autonomic nervous system (ANS). The aerobic training isolated or in association with the resistance training showed evidence of beneficial effects on an autonomic modulation of COPD; however, there are no studies addressing the effect of isolated resistance training. Aims. This study aims at investigating the influence of resistance training on an autonomic modulation through heart rate variability (HRV), functional capacity and muscle strength in individuals with COPD. Design. Clinical series study. Setting. Outpatients. Population. The study involved 13 individuals with COPD. Methods. The experimental protocol was composed by an initial and final evaluation that consisted in autonomic evaluations (HRV), cardiopulmonary functional capacity evaluation (6-minute walk test) and strength evaluation (dynamometry) in addition by the resistance training performed by 24 sessions lasted 60 minutes each one and on a frequency of three times a week. The intensity was determined initially with 60% of one maximum repetition and was progressively increased in each five sessions until 80%. Results. The HRV temporal and spectral indexes analysis demonstrates improvement of autonomic modulation, with significant statistical increases to sympathetic and parasympathetic components of ANS representing by SDNN, LF and HF. In addition, it was observed significant statistical increases to shoulder abduction and knee flexion strength and functional capacity. Corresponding author: A. L. Ricci Vitor, Departamento de Fisioterapia, Faculdade de Ciências e Tecnologia da Universidade Estadual Paulista (UNESP), Rua Roberto Simonsen 305, Centro Educacional, 19060-900 Presidente Prudente, Brasil. E-mail: [email protected]

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1Departamento

de Fisioterapia, Faculdade de Ciências e Tecnologia da Universidade Estadual Paulista (UNESP) Presidente Prudente, São Paulo, Brazil ²Departamento de Cardiologia e Cirurgia Cardiovascular da Faculdade de Medicina de São José do Rio Preto (FAMERP), São José do Rio Preto, São Paulo, Brazil

Conclusion. The exclusive resistance training performed was able to positively influence the autonomic modulation; in addition it promoted benefits on cardiorespiratory functional capacity and strength benefits in individuals with COPD. Clinical Rehabilitation Impact. This study could contribute to clinical and professionals researchers that act with COPD, even though the resistance component of pulmonary rehabilitation presents consensual benefits on several healthy indicators parameters. There is no evidence about the effects on HRV before. Moreover, this study showed, on clinical practice, the HRV uses as an ANS activity on sinus node evaluation and highlights further importance on scientific context. Key words: Autonomic nervous system - Resistance training - Pulmonary disease, chronic obstructive - Parasympathetic nervous system - Exercise.

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hronic obstructive pulmonary disease (COPD) defined as a progressive and not fully reversible chronic airflow limitation, is usually caused by the inhalation of cigarette smoke,1 and is among the major causes of morbidity and mortality, affecting around three million individuals worldwide and resulting in a heavy economical and social burden.1, 2 Among the systemic manifestations commonly observed in COPD are the reduction in type I muscle fibers, atrophy of fibers types I and II, a reduc-

EUROPEAN JOURNAL OF PHYSICAL AND REHABILITATION MEDICINE

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Resistance training in the chronic obstructive pulmonary disease

tion in capillarization and changes in metabolic enzyme levels that produce a decrease in strength and resistance and impact on functional limitations and on patient prognosis.3, 4 Furthermore, dysfunction of the autonomic nervous system is observed.5-9 Because of these alterations, signs and limiting symptoms such as dyspnea, fatigue and exercise intolerance presented by these patients, pulmonary rehabilitation is highly indicated in their treatment, with evidence of benefits in dyspnea, reduced hospitalizations, and improvements in psychosocial aspects, among others.1, 10-12 Regular physical exercise is an important component in pulmonary rehabilitation, and specifically on the impact of physical exercise programs on autonomic modulation, Borgui-Silva et al.13 studied the effects of an aerobic training program carried out on an ergometric treadmill, three times a week for six weeks, in patients with COPD and observed an increase in heart rate variability (HRV) indexes, indicating improved autonomic modulation. Camillo et al.14 evaluated the effects of high-intensity circuit training, which involved an aerobic component associated with a component resisted in these patients, and an improvement was also observed in the autonomic modulation on the Tilt maneuver. Yet, despite the beneficial effects induced by aerobic training in isolation or in association with resistance training on the autonomic modulation of COPD described in the literature, no studies were found which addressed the effects of resistance training in isolation; and the results in the few studies that have evaluated this in other populations 15-19 present no consensus. The hypothesis is that the autonomic modulation of patients with COPD could be improved by resistance training alone. Therefore, this study aims to investigate the influence of resistance training on autonomic modulation through HRV, functional capacity and muscle strength in individuals with COPD.

strength. It involved 13 out-patients referred to the Pulmonary Rehabilitation Center for Studies and Treatment in the School of Physiotherapy, of the Faculty of Sciences and Technology, UNESP, Presidente Prudente, São Paulo, Brazil, who presented the medical and spirometric diagnosis of COPD 1 and reported the absence of severe cardiovascular diseases, that could interfere with the performance of any parameter evaluated or with the conduct of the experimental protocol. Thirty-two volunteers participated in the initial evaluation. Among them, seven were excluded because they failed to meet the inclusion criteria; six were excluded for abandoning the exercise protocol for personal reasons; a further volunteer was excluded due to exacerbation with the process, along with five others who did not present 95% of sinus beats in the temporal series of intervals between consecutive cardiac beats used for analysis of HRV, as can be seen in diagram representing the flow of losses in Figure 1, as recommended by Martins et al.20 Those individuals who met the inclusion criteria were given an explanation of the objectives and procedures of the study and signed an informed consent form. All of the procedures used in this study were approved by the Research Ethics Committee of the same institution (Protocol No 42/2010).

Materials and methods Subjects This study is a longitudinal clinical trial that evaluated the effects of a 24-session resistance training program on HRV, functional capacity and muscle

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Figure 1.—Diagram representing the participants flow for steps of the study.


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height² (meters). The body weight was measured on a digital balance (Welmy, R/I 200, Brazil) with the volunteers wearing light clothes and barefoot in the orthostatic position. Height was measured using a stadiometer (Sanny, Brazil).21 Spirometry

Figure 2.—Time line representing the study design.

Study design The experimental protocol consisted of an initial evaluation, a program of resistance training, followed by a final evaluation (Figure 2). During the initial evaluation, details were taken of the volunteers’ medical history to determine whether they fulfilled the inclusion criteria; anthropometric, spirometric and autonomic evaluations were conducted, and measurements were taken of cardiopulmonary functional capacity and strength. Subsequently, the volunteers were subjected to resistance exercise which consisted of a one repetition maximum test (1RM). At the end of the resistance training program, the final evaluations consisted of autonomic, cardiopulmonary functional capacity and strength evaluations. Medical history The volunteer was identified and a thorough medical history was noted, with questions regarding any severe cardiovascular, neuromuscular, skeletal or lung associated diseases, any history of diseases and current clinical state (medications currently prescribed, the presence of diabetes, arterial hypertension and smoking risk factors). Anthropometry Anthropometry was performed to characterize the population and to investigate the presence of excess weight and obesity. The mass and the height were checked and the body mass index (BMI) was calculated by the following formula: mass (kilograms)/

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Spirometry was performed to confirm the diagnosis of COPD and to classify the severity of the airflow symptom 1 using the forced vital capacity test pre- and post-bronchodilator 22, 23 undertaken using a portable spirometer (MIR, Spirobank version 3.6, Italy) coupled to a microcomputer for analysis using Ocean and WinSpiro for Windows, version 1.04ª software. Heart rate variability The evaluations of heart rate variability in the initial and final period were performed to verify the autonomic modulation and volunteers were assessed individually in a room at a temperature of between 21 °C and 23 °C and humidity between 40% and 60% in the morning, between 8.00 and 12.00 to minimize the circadian rhythm interference. The volunteers were instructed to avoid alcoholic and/ or stimulant drinks such as coffee or tea, and those on continued used medication, such as bronchodilators, mucolytics and anti-inflammatory medicines, were requested to suspend their medication for a period of 12 hours prior to the autonomic evaluation. During the autonomic evaluation, the volunteers were instructed to remain alert, in silence, with spontaneous breathing resting in the supine position for 30 minutes on a couch. After receiving an explanation of the data collection procedures, an electrode was placed on the volunteer’s chest at the sternal angle using an elastic strap, and the heart rate receiver (Polar Electro, model S810i, Finland) was attached to the patient’s wrist. The equipment had previously been validated to record beat-to-beat heart rate and for use in collecting HRV data for analysis.24, 25 To analyze HRV indexes, 256 intervals of consecutive cardiac beats were used, selected after digital filtering, complemented by manual filtering to eliminate artifact and ectopic beats, and only series with more than 95% of sinus beats were included in the study; the analysis was processed by the Kubios


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(Biosignal Analysis and Medical Image Group, Department of Physics, University of Kuopio, Finland) software.26, 27 In the time domain, the following indexes were used: rMSSD (the root mean square of successive difference between normal intervals of consecutive cardiac beats in an interval of time expressed in milliseconds [ms]) and SDNN (the standard deviation of normal-to-normal intervals in an interval of time expressed in ms).24 In the frequency domain, the spectral components of low frequency (LF: 0.004 to 0.15 Hertz [Hz]) and high frequency (HF: 0.15 to 0.40Hz), expressed in ms² (ms squared) were calculated by the Fast Fourier Transform algorithm.28 6-minute walk test The 6-minute walk test (6MWT) was also performed at the initial and final evaluation to obtain the cardiorespiratory functional capacity in a safe manner.29 During the evaluation, the patients were informed of the test procedures and their arterial pressure, pulse oximetry, dyspnea level (Borg Scale), respiration and cardiac rate were all monitored. The test was performed in a space 30 meters in length, free of people in circulation. After each minute, standard words of encouragement were offered and the test was performed twice with the minimum interval of 30 minutes between them and the highest of the two values was considered. Dynamometry The measurement of strength was performed unilaterally (using the dominant member) at the initial and final assessment, using the digital dynamometer (Force Gauge®, model FG-100 kg, Brazil) with results expressed in Newton (N). The patients were instructed to execute maximum voluntary isometric contraction for six seconds resisted by a non-stretch strap attached to the dynamometer. One end of the strap was attached to the equipment and the other one to the body segment executing the movement. The measurement was repeated three to five times at an interval of one minute between them and the highest value was recorded. The positions of the individuals according to the movements evaluated are described below: a) knee flexion: sitting position, with hip flexion and knees at 90º. The strap was attached using the

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ankle adapter, and the patient was instructed to perform knee flexion against the resistance; b) knee extension: sitting position, with hip flexion and knees at 90º. The strap was attached using the ankle adapter, and the patient was instructed to perform knee extension against the resistance; c) shoulder flexion: standing position, with the shoulder at 70º and the elbow in prone position. The strap was attached to a hand grip and the patient was instructed to perform shoulder flexion against the resistance; d) shoulder abduction: standing position, with the shoulder at 70º and the elbow in prone. The strap was attached to a hand grip and the patient was instructed to perform shoulder abduction against the resistance; e) elbow flexion: standing position, with the arm attached to the lateral region of the body. The strap was attached to a hand grip and the patient was instructed to perform elbow flexion to 90º in supine position, against the resistance. 1RM test The 1RM test was performed before the resistance training to determine the work load using a pulley system (Ipiranga, Academia Hard, São Paulo, Brazil). The initial load was stipulated as 20% of body mass for the lower limbs and 5% for the upper limbs, with progressive 5% increments. The rest interval between each attempt was 5 minutes. The test was considered concluded when the volunteer attained the maximum load without mechanical failure. No more than 5 attempts were allowed for the establishment of the maximum load.30 The muscle groups tested to determine 1RM subsequently implemented were the same as those tested by dynamometry: knee flexion, knee extension, shoulder flexion, shoulder abduction, elbow flexion. Resistance training The resistance training was performed using the same equipment as in the 1RM test and was conducted over 24 morning sessions. Patients who missed any session continued the training until all sessions were completed. The sessions lasted 60 minutes and with a frequency of three times a week and were structured on: a) global stretching (muscles of body trunk, up-


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per and lower limbs) in the initial and final session; b) lower limb strength training (knee flexion and extension on leg bend or leg extension); c) upper limb strength training (shoulder flexion and extension and elbow flexion on a simple pulley equipment). The training intensity was determined initially with 60% of 1RM and was progressively increased in each five sessions up to 80%. Three sets of ten repetitions were undertaken for each of the muscle groups in training with two to three minutes between the sets.31-33 During all the training sessions the arterial pressure, pulse oximetry, dyspnea level (Borg Scale), respiration and cardiac rate were monitored with the aim of evaluating the clinical state and stability of the volunteers.

Table I.—Sample feature: gender, age, anthropometric and spirometric measures at mean, standard deviation, median, minimum and maximum. Feature

Gender (F/M) Age (years) Anthropometric measures Body mass (kg) Height (m) BMI (kg/m²) Spirometric measures FEV1/FVC (%) FEV1 (% predict) FVC (% predict) Stage II (moderate) Stage III (severe) Stage IV (very severe)

(N.=13)

5/8 67.15±7.34 (68) (56-82) 71.12±15.20 (74) (40-92) 1.64±0.08 (1.69) (1.47-1.74) 26.32±5.42 (27.18) (18.51-35.2) 54.06±8.99 (56) (40.10-67.90) 48.34±12.05 (46.93) (28.51-66.06) 69.02±15.12 (70.12) (41.33-91.92) 6 6 1

N.=number of sample; F/M: female/male; kg: kilograms; m: meters; BMI: body mass index; FEV1: forced expiratory volume in the first second postbronchodilator; FVC: forced vital capacity post-bronchodilator; %: percentage.

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Statistical analysis Statistical analysis was performed using the SPSS statistical package version 13.00 (SPSS, Inc. Chicago, IL, USA) software. Data were described to characterize the population as mean, standard deviation, median, minimum, maximum or absolute values and percentages. Data distribution was checked using the Shapiro-Wilk test and, depending on the data distribution, the paired t-test or Wilcoxon test were used. The level of statistical significance was set at P