Document Type : Review article
Subjects
Abstract
Pulmonary rehabilitation is an effective method to improve the clinical conditions of patients with Chronic Obstructive Pulmonary Disease (COPD), which includes providing a supervised exercise program at home or in a treatment center according to the patient’s conditions and abilities. Despite the many benefits of pulmonary rehabilitation, it has not received much attention in different countries. Pulmonary rehabilitation is done according to international general guidelines, but it is very important to develop center-based programs according to existing facilities and conditions. Currently, very few pulmonary rehabilitation centers are active in Iran. Considering the limitations in access to patients, and the importance of pulmonary rehabilitation in the treatment process of patients with COPD, in the present study, the pulmonary rehabilitation protocol, localized by National Research Institute of Tuberculosis and Lung Disease (NRITLD) in Tehran, Iran, has been presented.
Keywords: Attention, Chronic obstructive, Exercise therapy, Humans, Iran, Pulmonary disease, Rehabilitation centers, Tuberculosis
Introduction
An overview of what is common in the world
Various conventional methods for exercise training of patients with Chronic Obstructive Pulmonary Disease (COPD) who participate in pulmonary rehabilitation programs mainly include endurance training (continuous or intermittent) and strength training.
Endurance training
Endurance training is the most common exercise method in patients with COPD. The main goal of endurance training is to improve aerobic exercise capacity, since aerobic activities are part of many daily tasks in these patients. Endurance training has also been shown to improve peripheral muscle function in patients with COPD (1). In addition, there is evidence that high-intensity endurance exercise produces greater physiological benefits than lower-intensity exercise (2). However, most patients with severe COPD are unable to continue high-intensity exercise due to serious symptoms such as dyspnea and fatigue (3). Therefore, alternative exercise protocols, such as interval training, have received increasing attention, especially in patients with advanced COPD.
Continuous training versus intermittent training
Historically, interval training involves the ability of high-intensity exercise on the peripheral muscles without putting too much strain on the cardiorespiratory system. As previously mentioned, people with COPD have a different response to exercise compared to healthy people due to the factors that limit physical activity.
A systematic review including eight randomized controlled trials with 388 COPD patients compared the effects of continuous and intermittent exercise (4). It was found that both methods led to comparable improvements in exercise capacity and health-related quality of life. However, in patients with very severe COPD, there is evidence that interval training is associated with fewer symptoms of dyspnea during exercise and fewer unwanted interruptions (5-7).
Interval training consists of a sequence of pressures applied to the muscles alternately (on and off), however, it has been revealed that it is easier to tolerate for the respiratory and peripheral muscles than training with a constant load (9).
In general, many patients suffer from physical limitations in daily life. To avoid patients’ disappointment in doing sports exercises, providing specific exercise protocols for each patient can help in this field. It seems that this can improve patients’ motivation and in some cases increase long-term adherence to exercise programs. However, in patients with COPD, especially older people, patients should familiarize themselves with the state of exercises and rest intervals first so that they can follow the proper order of work and rest intervals for the required period.
An easy approach to target training intensity for continuous training [60%: Peak Work Rate (PWR)] and interval endurance training (80% PWR) on the bicycle is to derive the training intensity from a certain percentage of peak workload. For more effective and feasible cycling load adjustment, patients’ modified Borg scale (0-10) should be between 4 and 6. Table 1 shows some practical recommendations for implementing continuous and interval endurance training programs.
Table 2 shows the parameters that determine when to use the interval training protocol. If the patient is borderline at some of these points, it is recommended that the patient be allowed to decide which exercise protocol they prefer. The patient can try both methods in the first days of the pulmonary rehabilitation program and share his opinion. Using patients’ opinions in planning the exercise program can improve their willingness to adhere to the intervention.
Oxygen supplement consumption during exercise
The benefits of Long-Term Oxygen Therapy (LTOT) in patients with COPD associated with hypoxemia are well known. In these patients, LTOT prolongs survival and reduces hospitalization as well as the risk of comorbidities (18,19). Recently, the usefulness of oxygen therapy in improving pulmonary rehabilitation outcomes in patients with COPD has been evaluated in several studies. Supplemental oxygen therapy has been studied in patients who are severely hypoxemic at rest or with exercise as an adjunct to exercise training. The rationale of these studies is that supplemental oxygen therapy improves peripheral muscle oxygenation (20), dyspnea (21), and exercise capacity (22) in patients with COPD and hypoxemia, possibly allowing them to exercise at a higher intensity. The oxygen saturation level measured by pulse oximeter should be more than 90% or arterial oxygen pressure should be more than 55 mmHg (24).
Strength training
Peripheral muscle dysfunction and muscle weakness are among the most common comorbidities in COPD patients that lead to exercise intolerance and worsening symptoms (26,27). It is hypothesized that resistance training can reverse peripheral muscle dysfunction and thereby, at least partially, reduce the burden of COPD (28). Resistance training is recommended as an adjunct to improve endurance in all patients, especially those with peripheral muscle weakness. Considering that strength training has a greater potential to improve muscle mass and strength than endurance training (29,30), a combination of these two exercise methods is highly recommended. Strength training also produces less dyspnea during exercise, likely making it easier to tolerate than aerobic exercise (31).
A systematic review that included 18 randomized controlled trials demonstrated consistent improvements in muscle strength despite wide variation in training characteristics, such as the number of repetitions, training intensity, or the strength training method itself (32). Another important and clinically relevant finding of this article was that the effects of strength training can lead to significant changes in the patient’s functional activities such as climbing stairs or lifting objects (32).
Table 3 lists the parameters related to strength training (33). The principle of deriving strength training intensity from 1RM (repetition maximum) should be carefully considered. Due to the large inter-individual variability and the wide range of variation in the number of repetitions possible at a given percentage of 1RM, the degree of muscle fatigue was considered carefully for more precision in achieving the intensity of strength training (34,35). Therefore, the main focus can be on targeting local muscle fatigue in the 6-12 repetition range (or setting a 6-12 repetition maximum). An easy and very practical way to determine the optimal resistance for strength training is for the physiotherapist to set the training load based on 1RM so that the patient can repeat an exercise six to a maximum of 12 times before stopping due to muscle fatigue. When the subject can perform the current workload for one or two more repetitions than the desired number of six to 12 repetitions in two consecutive training sessions, it is recommended to apply a 2 to 10% increase in load (36).
Table 1. Practical recommendations for the implementation of continuous and periodic endurance training programs
|
|
Continuous endurance training |
Interval endurance training |
|
Frequency |
All days of the week |
All days of the week |
|
Moderate |
Continuous |
Interval Modes: 30 s exercise, 30 s rest 20 s exercise, 40 s rest |
|
Intensity |
- Initially with 60-70% PWR - Increase workload with 5-10% tolerance - Advance training and effort until reaching ~ 80-90% of initial power |
- Start with 80-100% PWR for the third or fourth session - Increased workload up to 5-10% tolerance - Advance until reaching ~ 150% of initial power |
|
Duration |
- Start with 10-15 min for the first 3 or 4 sessions - Advancing exercises by increasing the duration of 30-40 min |
- Start with 15-20 min for the first three or four sessions - Advancement of exercises by increasing the duration up to 15-60 min (with rest time) |
|
Perceived exertion |
Trying to maintain Borg scale 4 to 6 |
Trying to maintain Borg scale 4 to 6 |
|
Breathing technique |
Suggest breathing with pursed lips or using PEP devices to prevent dynamic hyper infiltration and reduce breathing frequency |
Suggest breathing with pursed lips or using PEP devices to prevent dynamic hyper infiltration and reduce breathing frequency |
PWR: Peak Work Rate, PEP: Positive Expiratory Pressure.
Table 2. Practical indications for considering the use of interval training approach
|
Interval training may be more appropriate when the patient presents with: |
|
Severe airflow obstruction (FEV1 <40% pred) |
|
Low training capacity (peak work rate <60% pred) |
|
Total time in a constant work rate test <10 min |
|
Significant oxygen desaturation during exercise (SpO2 <85%) |
|
Unbearable dyspnea during sustained endurance exercise |
FEV1: Forced Expiratory Volume in the first second.
Table 3. Practical recommendations for performing the strength training
|
Frequency |
2-3 days per week |
|
Purpose |
Targeting localized muscle fatigue at a specified number of repetitions for major muscle groups of the upper and lower limbs |
|
Moderate |
2-4 sets of 6-12 repetitions |
|
Intensity |
50-85% of one repetition maximum as a reference point, if possible one to two repetitions more than desired in two consecutive training sessions, increase the workload by 2-10% |
|
Speed |
Medium (1-2 s concentric and 1-2 s eccentric) |
Table 4. The difference between National institute of tuberculosis and lung disease of Masih Daneshvari Hospital pulmonary rehabilitation protocol and the international protocol
|
|
Type of patient |
The duration of rehabilitation |
Number of rehabilitation sessions per week |
Exercise intensity |
Duration of each training session |
Type of rehabilitation exercises |
|
NRITLD protocol |
Inpatients |
≥2 weeks |
6 times |
80% of the 6MWT test |
10 to 40 min |
Treadmill, bicycle, walking, strength exercises, stretching, dumbbells, exercise stretch, breathing exercises |
|
Common protocol |
Outpatient |
≥4 weeks |
3 times |
60-70% PWR |
15 to 60 min |
Treadmill, bicycle, strength training |
NRITLD: National Institute of Tuberculosis and Lung Disease, 6MWT: Six Minute Walk Test, PWR: Peak Work Rate
Pulmonary rehabilitation at Masih Daneshvari Hospital
The pulmonary rehabilitation team of Masih Daneshvari Hospital, Tehran, Iran, consisting of pulmonary therapists, physical medicine, physiotherapists, and nurses, has been working as the first pulmonary rehabilitation center in Iran for nearly 10 years. Therefore, based on the results of treatment experiences, while modeling the international trend, they have taken a kind of localization of the rehabilitation protocol for patients with COPD, which is optimized and implemented according to the conditions governing the treatment team and the clinical condition of the patients.
One of the unique features of lung rehabilitation in this hospital is the presence of an inpatient ward for lung rehabilitation. Chronic respiratory patients who need medical services, oxygen therapy, physiotherapy, and non-invasive ventilation are admitted to this department and receive these medical services on a regular basis. Generally, as soon as patients are admitted to the ward, they are visited by a pulmonologist and receive the necessary prescriptions for medication, oxygen therapy, and non-invasive ventilation. Then, if the patients reach a stable condition and have no acute condition (exacerbation), they are evaluated by a specialist physician. These evaluations include the following:
Investigating contraindications for physical therapy and exercise therapy, such as thrombosis, embolism, orthopedic or neurological problems, etc.
Examining the patient’s conditions in terms of the amount of oxygen needed in two states of rest and activity
Examining the patient’s conditions in terms of the need for airway clearing techniques
Examining the conditions of the patient’s breathing patterns and the function of the respiratory muscles
Examining the strength of the muscles of the lower limb (quadriceps muscle) and upper limb (grip strength of the hands)
Also, in order to check the effect of rehabilitation exercises, the following indicators are used:
The 6 Minute Walk Test (6MWT)
Sit to stand
modified Medical Research Council (mMRC)
The COPD Assessment Test (CAT)
St. George’s Questionnaire
After performing the initial evaluations and recording the results of the tests, the lung rehabilitation programs are implemented by the physiotherapist in the following order:
Implementation of airway clearance techniques of necessary and needed by the patient
Teaching correct breathing patterns, including diaphragmatic breathing, pursed lip breathing, chest expansion exercises, not using respiratory muscles, and teaching methods to overcome dyspnea.
Performing strength exercises according to the patient’s condition on the bed
Lowering the patient from the bed and performing balance exercises according to the patient’s condition
Referring the patient to a special hall for aerobic and resistance exercises
How to exercise in a special hall
At first, the method and purpose of exercise are explained to the patient by the physiotherapist, and aerobic exercise begins by using a stationary bike. In patients who have the condition to use a treadmill, exercise on a stationary bike is considered as a warm-up phase (for a maximum of 10 min) and then the main aerobic exercise begins on the treadmill. If the patients are unable to use a treadmill due to orthopedic problems or severe weakness, they use a stationary bike for 10 to 15 min with 1-2 load. If the patient’s conditions are suitable for using the treadmill, the procedure is as follows:
- Initial warm-up using a stationary bike for 5 to 10 min
- Performing pulse oximetry of the patient to check the need for oxygen therapy and the amount of oxygen flow
- Starting walking on the treadmill at a speed of 1 km/hr
- Increasing the speed according to the intensity obtained from the 6-min walking test
To determine the intensity of exercise based on the 6-min walking test, the distance obtained in this test is converted into kilometers per hour, and then 80% of it is used to start training on the treadmill.
- Exercise for 10 to 20 min according to the patient’s tolerance
- Gradual return to a speed of 1 km/h in the last 2 min as a cooling phase
- Doing stretching exercises on the upper and lower limbs after finishing the treadmill
All the steps of the above exercises are performed for patients 6 days a week. Usually, on 3 days out of these 6 days, resistance exercises including the use of elastic bands (any type) and light dumbbells are also performed in the gym for patients.
Normally, patients are hospitalized for an average of two weeks, and at the time of discharge, the indicators of lung rehabilitation are measured and recorded again. At the time of discharge, the required educational pamphlets are provided to the patients (Figure 1). The main differences between the pulmonary rehabilitation method in the rehabilitation department of Masih Daneshvari Hospital and the common international protocol are presented in table 4.
Conclusion
Pulmonary rehabilitation is one of the treatment lines of COPD, the most important part of which is providing exercise training. Novel and localized models of pulmonary rehabilitation help to optimally use local resources, strengthen the health system, and improve pulmonary rehabilitation outcomes. Considering the quality of pulmonary rehabilitation programs and providing suitable suggestions for when and how to perform exercises plays a significant role in the progress of pulmonary rehabilitation programs.
Acknowledgement
The current study was registered with ethics code IR.SBMU.NRITLD.REC.1402.139 by the ethics committee of Pulmonary Rehabilitation Research Center, Masih Daneshvari Hospital, Tehran, Iran.
Conflict of Interest
Authors declare no conflict of interest.
References
