Effects of a home-based exercise program after supervised resistance training in patients with chronic obstructive pulmonary disease

Design of the study: clinical Trial. Objective: This study aimed to evaluate the effects of a homebased resistance exercise program with elastic tubing after supervised resistance training on peripheral muscle strength and quality of life in patients with chronic obstructive pulmonary disease (COPD). Methods: The study included 22 COPD patients, aged 55-70 years. Peripheral muscle strength and quality of life were evaluated through digital dynamometer and Chronic Respiratory Disease Questionnaire (CRDQ) respectively after supervised resistance training program, and then the patients were divided into two groups: home-based treatment (n = 10) and control (n = 12). After 16 weeks the assessments were repeated. Results: The home resistance training showed no significant increase in peripheral muscle strength and quality of life, however, was able to maintain the gains made in the previous supervised training. Conclusion: The continuity of home-based treatment did not promote additional improvements to supervised training after the protocol, since the gains were maintained in both assessed groups after 4 months.


Participants
The sample consisted of volunteers in primary, sent both the public system and the private system to the Study Centre and Service in Physical Therapy and Rehabilitation, Faculty of Science and Technology -FCT / UNESP -Presidente Prudente campus.
The recruited subjects participated in another original study of pulmonary rehabilitation, whose exclusion criteria were: not to be in smoking abstinence for at least a year, presence of disabling and / or unstable heart disease that could influence the performance of physical activity, exacerbations or changes in medication in the last 30 days and use of home oxygen therapy.
The study evaluated the effect of a 16 weeks home-based program after supervised resistance training on peripheral muscle strength and quality of life of 22 patients diagnosed with COPD according to the criteria established by the Global Initiative for Obstructive Lung.Disease. 1 Patients were informed about all the procedures and objectives of the study and, after agreeing, signed a consent form.All procedures used in this study were approved by the Institutional Ethics Committee (Protocol: 104/2010).Universal Trial Number: U1111-1159-7179.

Experimental Design
At the end of a supervised resistance, training program 13 patients were invited to continue their resistance training with elastic tubing at home for 16 weeks.Patients who chose willingly to continuing treatment in the home environment made up the home-based treatment group and those who did not want to continue agreed to participate of the evaluations proposed thus composing the control group.
The study was conducted from July to October 2013 and the experimental protocol consisted of an evaluation performed at baseline and after 16 weeks of home-based resistance training.We per-

Introduction
Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease with significant systemic effects which contributes to the severity of symptoms. 1The disease affects 85% of smokers aged over 40 years and is estimated to be the third leading cause of death worldwide by 2020. 1 The management of COPD involves drug therapy, smoking cessation, and participation in pulmonary rehabilitation programs. 2ulmonary rehabilitation is widely recommended for patients with COPD and aims to improve peripheral muscle strength and quality of life. 3However, not all patients adhere to rehabilitation programs.Travel and transportation are often cited as barriers to achieving center-based programs.Other models of pulmonary rehabilitation, including home-based programs, have been proposed to improve access in the treatment to COPD patients. 4,1 major component of pulmonary rehabilitation is exercise.Among its modalities, resistance training proves to be able to improve functional performance, quality of life, reduce sensitivity to dyspnea and reverse, partially, peripheral muscle dysfunction in COPD. 5,6,7owever, these benefits begin to decrease after 30 days of discontinuing rehabilitation program. 8,9Thereby; home-based training programs have been proposed for the maintenance of gains after conclusion of supervised rehabilitation programs. 10,11,12t is known that the equipment commonly used to practice resistance training require large physical space, are difficult to move, and present a high cost, which difficult its acquisition in a home environment.Thus, the elastic tubing appears as an additional alternative, presenting a viable treatment for these patients 13,14 and has proved to be a safety feature, easy to manipulate and inexpensive. 15Despite these advantages, not much is known about the effects of this tool in a home-based resistance program in patients with COPD.
Therefore, this study aimed to evaluate the effects of a home-based resistance exercises program with elastic tubing, after supervised training on peripheral muscle strength and quality of life in patients with COPD.In patients in home-based training group, the fatigue resistance test with elastic tubing was performed to determine the initial training load.This test was repeated every 4 weeks for load increase.The control group was instructed not to perform any type of physical activity during the 16 weeks.

Pulmonary Function
For the evaluation of Lung.function, spirometry was performed using spirometer MIR-Spirobank version 3.6 coupled to a microcomputer.The data interpretation was in accordance with the standards of the American Thoracic Society and European Respiratory Society. 16The normality values were considered to the Brazilian population. 17

Resistance to fatigue test
The determination of the training load through the fatigue resistance test was obtained from the higher number of repetitions of each performed movement (knee extension and knee flexion, shoulder abduction and shoulder flexion), until it was reached muscle fatigue.The number of repetitions and the time were timed (40-60 seconds) until the patient reached exhaustion.This was used as a reference value to obtain the number of repeats proportionate to 20 seconds.This is the time which the adenosine triphosphate-creatine phosphate (ATP-CP) system is consumed by muscle cells for energy. 18atex elastic ropes tube-type was used for test execution.It was standardized thickness of two millimeters for upper limbs and four millimeters to lower limbs.The test was considered ideal when the reported fatigue was at the time of 45 ± 5 seconds.From the results obtained in the fatigue resistance test, we determined the number of sets and repetitions for each specific muscle group trained. 13

Home-based Resistance Exercise Protocol
After the initial assessments, we conducted home visits for the training group aiming to adapt the place for the exercises.Besides, a book of guidance and control of physical activity was provided to the patients.Also we weekly contacted the patients through phone to control the routine of exercises and their general health.
During the 16-week treatment, home-based group performed a resistance exercise protocol with elastic tubing (Lemgruber ® brand, Brazil), with a frequency of three times a week, without direct supervision.The patients were previously informed about the correct way to perform each one of the exercises.The following movements were executed: knee flexion, knee extension, shoulder flexion and shoulder abduction.
The prescription of repetitions and the determination of the exercise load were based on resistance of fatigue test with elastic tubing, performed individually and specific to each movement.The protocol started with 2 sets and the load was progressively increased by adding one more set every two sessions, ending with 7 sets, completing 4 weeks of training.Then, a new fatigue resistance test was performed and carried out a new prescription.The new prescription was always performed after the end of 4 weeks of training. 13

Quality of life
To assess quality of life, the Chronic Respiratory Disease Questionnaire (CRDQ) was applied. 19he questionnaire contains 20 questions divided into four domains: dyspnea (5 questions), fatigue (4 questions), emotional function (7 questions) and illness control (4 questions).The questionnaire was administered by a single interviewer in all periods.The evaluation was performed at baseline, after completion of the supervised program and after four months of home monitoring.

Measurement of peripheral muscle strength
The measurement of peripheral muscle strength was performed unilaterally (dominant limb) through digital dynamometer Force Gauge® brand, model FG-100 kg.The results were expressed in Newtons.The patient was instructed to perform the movement (knee extension, knee flexion, shoulder flexion and shoulder abduction) against the resistance of a steel cable attached to the dynamometer.The patient underwent his maximal voluntary isometric contraction (MVIC) for 6 seconds, followed by relaxation of the limb.The measurement was repeated three times, with an interval of 1 minute between them, and the highest value was recorded. 20

Statistical Analysis
Data analysis was performed in GraphPad Prism® software.The normality of data was per-
Table 1 demonstrates that there was no difference among the groups in relation to anthropometric and spirometric data.
Table 2 shows baseline values and after 16 weeks of training of peripheral muscle strength and CRDQ domains.No change during the protocol was observed in both groups.Table 3 shows the values of peripheral muscle strength and CRDQ domains after home-based training, which showed similar behavior.No significant differences were observed between groups.

Discussion
The study showed that during the 16 weeks of monitoring, the home-based exercise and control groups maintained the values obtained after a period of supervised training on peripheral muscle strength and quality of life.Data presented as mean and standard deviation.N = Newton.Our results corroborate with the findings of O 'Shea et al., (2007) that assessed COPD patients undergoing domiciliary resistance training with progressive load (elastic bands) for a period of 12 weeks, after a supervised training period and observed no significant differences in peripheral muscle strength and quality of life for these patients compared with the control group. 15nother study by Spencer et al., (2010) also showed maintenance of the gains on quality of life after a supervised rehabilitation program.In this study the home-based training was combined, 30 minutes of walking and 30 minutes of exercises for upper and lower limbs with free weights.The follow-up was for 12 months. 21n the other side, Brooks et al., (2002) showed a decline in CRDQ domains over 12 months for a home-based exercise program with monthly supervision.The study indicated that the frequency of supervision was insufficient to maintain the gains achieved after the supervised program. 22oulin et al., (2009) found gains on quality of life, through CRDQ, during six months of treatment with aerobic exercises at home in patients with COPD who have previously participated in a supervised pulmonary rehabilitation program. 23revious studies in patients with COPD that performed home-based intervention programs, demonstrated a variation in the frequency of supervision: once a week, 24,25 three times a week, 26 and once a month. 27,22The frequency of supervision appears to be related to the results obtained in this mentioned studies.Dodd et al., (2007) demonstrated that a home-based rehabilitation program for healthy elderly, showed lower results compared to center-based rehabilitation programs 28 , which may be a consequence of lack of supervision.
The impact of exercise training programs at home may be influenced by several factors, such as age, sex, socioeconomic status and anxiety. 29nother important factor demonstrated in the study of Brooks et al., (2002) was the decline in the number of patients in the course of home treatment.The purpose of the study was a 12 months follow-up, although it was observed a decrease in adherence, near half the patients dropped the program nine months after starting the treatment. 22 the present study we also observed a decrease in the number of patients who completed the homebased training, but these aspects were not the primary objective of this study.
Limitations of the study should be considered: First, the number of patients who completed the study protocol was relatively low.Second, we note the difficulty of adjusting the elastic tubing on conventional chairs found in patients homes, since in the supervised training the chair of the rehabilitation center were taller, which facilitated the execution of flexion and knee extension.This factor may have limited the performance of patients and difficult the achievement of better results.
In addition, we believe that no supervision of exercises in the household may have been a limiting factor in relation to patient compliance and therefore the results obtained.Considering that they had conducted a supervised training program, where we observed that patients trust the therapist and feel encouraged by the treatment group.So when made the proposal to continue at home without supervision we could observe accepted limitations on the continuation of the protocol.
Although gains in the evaluated periods were not evidenced in the home-based treatment, the proposed protocol has shown to be viable, safe and able to offer patients the ease and comfort of carrying out their treatment at home.Caring for adequacy for performing movements must be observed, as well as more frequent monitoring during the first days of the exercise protocol.The continuation of treatment, motivation, monitoring and supervision are critical aspects for patients after conclusion of a pulmonary rehabilitation program.
The study concluded that the continuity of home-based treatment, instructed but unsupervised, did not promote additional improvements to supervised training after the protocol, since the gains were maintained in both assessed groups after 4 months.

Table 1 . Anthropometric and spirometric data of patients with COPD.
Bertolini GN, Ramos D, Leite MR, Carvalho Junior LCS, Freire APCF, Lima FF, Silva BSA, Pastre CM, Ramos EMC.Home-Based exercise program and resistance training.