Presented here is a protocol to investigate the effects of home-based prescribed pulmonary exercise in stable chronic obstructive pulmonary disease (COPD) patients, which is modified based on traditional Chinese exercises according to dyspnea and limited exercise capacity observed in COPD patients.
As a systemic disease, chronic obstructive pulmonary disease (COPD) affects the respiratory system, inducing restless and exercise dyspnea. It also impacts exercise capacity and forms a vicious circle in which it further aggravates the condition of patients and accelerates disease progression. As a functional holistic exercise, traditional Chinese exercises (TCE) play an important role in the rehabilitation of COPD on the basis of adjusting the breath and performing coordinated movements. This study investigates the effects of prescribed pulmonary exercises (which are modified from TCE) on exercise capacity of upper and lower limbs, endurance exercise capacity, and quality of life in stable COPD patients. The goal is to determine the accessibility of these prescribed exercises in COPD rehabilitation. Participants are randomly divided into a non-exercise control group (CG) or prescribed pulmonary exercise group (PG) at a ratio of 1: 1. The PG receives intervention for 60 min twice per day, 7 days a week, for a total of 3 months. The intensity is measured using the Borg category-ratio 10 scale and with a heart-rate monitor. Then, an exercise capacity test and quality of life questionnaire are scheduled at 1 week before and after the formal intervention. After 3 months of intervention, the 30 s arm curl test, 30 s sit-to-stand test, 6 min walking test, and quality of life show significant improvement in COPD patients (p < 0.05). These findings indicate that prescribed pulmonary exercises can be applied as alternative, convenient, and effective home- and community-based exercises for stable COPD patients.
Chronic non-communicable diseases have gradually become the biggest threat to global health, accounting for 70% of global mortality. A majority of such deaths have been caused by four main diseases, while COPD ranks third and only falls behind cardiovascular disease and cancer. Moreover, the ranking of COPD in leading to years of life lost has risen from eleventh in 2007 to seventh in 20171. This change indicates unsatisfactory effects of current treatments in the rehabilitation of COPD progression. More studies have recognized that COPD is not only a respiratory disease but also a complex, multi-systemic, and multi-complicative condition2,3. COPD complications (i.e., skeletal muscle dysfunction) exist in all stages of the disease and play an important role in progression and prognosis4. Considering interactions between the respiratory symptoms and exercise capacity, rehabilitation of exercise capacity has received a lot of attention.
Pulmonary rehabilitation as a comprehensive intervention program, including but not limited to exercise training, health education, and self-management, has demonstrated effectiveness on physical and psychological condition of COPD patients5. Among the different types of exercise training, aerobic exercise plays a critical role in the improvement of endurance performance and muscle power6. In contrast, resistance exercise shows advantages in the improvement of muscle strength and functional exercise capacity7. Moreover, the interventional mechanisms of these two exercise types are distinct. Compared to resistance exercise, aerobic exercise is more effective in modulating inflammatory cytokine levels and inducing oxidized phenotypes of the quadriceps8,9.
Although the effects of these two conventional exercises in pulmonary rehabilitation has been demonstrated, regardless of the location (in hospital or at home)10,11, implementation of conventional exercise training is still limited due to the requirements of specific equipment, spacious room, and safety monitoring. These constraints not only inflict a burden on a patient’s family but also to the healthcare system. Alternative interventions such as neuromuscular electrical stimulation and whole-body vibration training share the same constraints12,13.
Traditional Chinese exercises (TCE), including tai chi, liu zi jue, wu qin xi, ba duan jin, and yi jin jing, belong to the self-exercise category, which focuses on adjustment of the breath accompanied with coordinated movement. These exercises also rely on psychological-physiological-morphological mechanisms to achieve health-related fitness. Previous studies have shown that 1) TCE as a low-and medium-intensity aerobic exercise induces a maximum heart rate of 43%–49%14, 2) exercise intensity ranges from 1.5 to 2.6 metabolic equivalents of energy (METs)15, and 3) it exerts positive effects in patients with stable COPD through clinical and family rehabilitation16,17,18,19. Compared to conventional exercise training, the advantage of TCE is that it is easy to execute at home without any equipment or spatial constraints.
As a modified TCE, the prescribed pulmonary exercise described in this protocol has been developed from the theory of traditional Chinese medicine and aims at the rehabilitation of COPD dyspnea and exercise capacity. Previous studies have showed significant improvements in the exercise capacity (assessed by 6 min walking test, 6MWT), daily life (Zhongshan COPD questionnaire for quality of life), and systemic inflammation levels in COPD patients after prescribed pulmonary exercise20. However, the effects of prescribed pulmonary exercise on the exercise capacity of upper and lower limbs and quality of life in COPD patients is still unclear.
This study compares 3 months of usual medicinal treatment without exercise intervention (control group, CG) vs. 3 months of prescribed pulmonary exercise intervention (PG) in stable COPD patients to investigate the effects of prescribed pulmonary exercise. The effects on upper limb exercise capacity are evaluated by the 30 s arm curl test, effects on lower limb exercise capacity evaluated by the 30 s sit-to-stand test (30 s SST), effects on endurance exercise capacity evaluated by the 6 min walking test (6MWT), and effects on quality of life evaluated by St. George’s Respiratory Questionnaire (SGRQ).
The protocol has been approved by the Ethics Committee of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine affiliated with Shanghai University of Traditional Chinese Medicine (Shanghai, China).
1. Video construction and study design
2. Power calculation
3. Participant recruitment
NOTE: Participant recruitment in this example was conducted in the Department of Respiratory, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine.
4. Training
5. Outcome assessment
NOTE: Conduct an assessment session within 7 days before and after the formal intervention.
6. Statistical analysis
The protocol above describes a randomized controlled trial to investigate whether prescribed pulmonary exercise improves exercise capacity and quality of life in stable COPD patients. While 44 participants were recruited, only 37 (84%) participants completed the study (CG = 19, PG = 18). Thus, data analysis was carried out using the 37 participants, and the two groups showed no significant differences in basic characteristics including age, sex, BMI, duration, and disease grade (Table 1).
After 3 months of intervention, repetition of: the 30 s arm curl test increased from 21.3 ± 4.4 to 22.9 ± 4; the 30 s SST increased from 16.8 ± 1 to 19.7 ± 3.5 (p = 0.001, Figure 3); and the distance in meters of 6MWT increased from 501.26 ± 74.08 to 535.78 ± 55.09 (p = 0.005) in PG. Between-group comparisons found that the improvement of exercise capacity in PG was significantly different from CG (p < 0.01). In addition, the activity score of SGRQ in CG showed a significant increase (p = 0.01), while the total and item scores of SGRQ in PG showed significant decreases (p < 0.01, Figure 4). Between-group comparisons showed that improvement of SGRQ in the PG was significantly different from that in the CG (p < 0.01).
Figure 1: Main characteristics of prescribed pulmonary exercises.
These pictures were originally published in Liu et al.22
Figure 2: Schematic diagram of the protocol.
The pre- and post-tests are similar. Further details are given in the text. Please click here to view a larger version of this figure.
Figure 3: Exercise capacity before and after 3 months of intervention.
CG = control group; PG = prescribed pulmonary exercise group; 30 s SST = 30 seconds sit-to-stand test. Data are expressed as mean ± SD. Within-group comparisons were calculated using the paired sample t-test (**p < 0.01, meaning that the comparisons were significant within groups). Please click here to view a larger version of this figure.
Figure 4: Quality of life before and after 3 months of intervention.
CG = control group; PG = prescribed pulmonary exercise group; SGRQ = St. George's Respiratory Questionnaire. Data are expressed as mean ± SD. Within-group comparisons were calculated using the paired sample t-test (*p < 0.05, **p < 0.01, meaning that the comparisons were significant within groups). Please click here to view a larger version of this figure.
Parameter | CG (n=19) | PG (n=18) | P-value |
Age (years) | 64.58 ± 9.06 | 66.11 ± 9.08 | 0.61 |
Sex | |||
male (n/%) | 14 (74%) | 15 (83%) | 0.69 |
female (n/ %) | 5 (26%) | 3 (17%) | |
BMI (kg/m2) | 22.90 ± 3.71 | 25.22 ± 0.82 | 0.61 |
Disease duration (years) | 11.12 ± 4.66 | 10.28 ± 5.67 | 0.64 |
AECOPD (repetitions) | 1.16 ± 0.21 | 1.06 ± 0.31 | 0.5 |
Disease grade | |||
I (n/%) | 2 (11%) | 1 (6%) | 0.64 |
II (n/%) | 11 (58%) | 10 (55%) | |
III (n/%) | 5 (26%) | 7 (39%) | |
IV (n/%) | 1 (5%) | 0 (0) | |
Treatments | |||
Long-acting cholinergic (n/%) | 9 (47%) | 9 (50%) | 0.76 |
Inhaled corticosteroids associated with long-acting β2-agonists (n/%) | 9 (47%) | 7 (39%) | |
No treatments (n/%) | 1 (6%) | 2 (11%) | |
Comorbidities | |||
Hypertension (n/%) | 10 (53%) | 9 (50%) | 0.88 |
Diabetes (n/%) | 5 (26%) | 6 (33%) | |
No comorbidities (n/%) | 4 (21%) | 3 (17%) |
Table 1: Basic characteristics. CG = control group; PG = prescribed pulmonary exercise group; AECOPD = acute exacerbation of chronic obstructive pulmonary disease.
In this study, a modified TCE referred to as prescribed pulmonary exercise is used in an intervention program, and a number of fitness tests are used to investigate the effects of home-based prescribed pulmonary exercise on exercise capacity and quality of life in stable COPD patients. The main finding is that many improvements occurred in upper and lower limb exercise capacity, endurance exercise capacity, and quality of life after 3 months of intervention. The results indicate that prescribed pulmonary exercise as a COPD-targeted and easy-to-study TCM can be used in home- and community-based COPD rehabilitation programs.
The completion rate of 84% after 3 months of intervention in this study is comparable to 90% in a previous study that adopted tai chi in COPD patients. The intervention program is 60 min each, once per day, 7 days a week (2 days in the hospital and 5 days at home), for a total of 12 weeks28. However, another study that applied the ba duan jin exercise as an intervention in COPD patients (age: 73.12 ± 1.33, FEV1%pred: 36.75 ± 2.11) only led to a completion rate of 65%, which was once per day, 4x per week, for a total of 6 months19. This may be attributed to the patients’ ages, in which all were above 70 years old, and that the FEV1%pred were all under 40%. In addition, a longer intervention with only four repetitions of instructions may be a reason for higher drop-out rates. Surprisingly, a study using liu zi jue as an intervention (with a similar program to the ba duan jin study mentioned above) reached a 94% complete rate16. It can be speculated that the duration of intervention and age of participants minimally affects the complete rate, while the type of intervention and severity of disease affects influences it comparatively more. However, a systemic and comprehensive method should be developed to investigate the possible factors affecting attrition rates when TCE is used as an intervention.
Elderly COPD patients may have difficulties with sustaining stable conditions during the 3 months of intervention. Researchers should be aware of the risk of acute exacerbation due to possible climate changes and various injuries due to training and testing. However, no injury or discomfort related to training or testing occurred during the intervention period among these participants. Modifications can be made regarding the specific motions in prescribed pulmonary disease according to the abilities of participants. Regarding the home-based intervention regime, the quality of accomplishment and compliance of participants is hard to guarantee. Therefore, the prescribed pulmonary exercise video, exercise record brochure registered by participants themselves, and encouragement and instruction from therapists play an irreplaceable role in the accomplishment of intervention.
During the upper limb exercise capacity test, it is important to avoid errors in the measurement procedure including activity of upper arm, movement of the wrist, and incomplete extension intermittent with the flexion, which ensures that participants perform maximally. Possible errors in lower limb exercise capacity are important to avoid, which are mainly present during the process of knee flexion intermittent with the extension. For this reason, it is valuable to require warm-up and familiarization exercises.
Furthermore, endurance exercise capacity was evaluated by 6MWT in an unobstructed 30 m straightway, which is more commonly used in clinical evaluation. Previous studies have found that the 6 min stepper test performed with no technical and spatial limitations can be used as a valid clinical exercise tolerance test for COPD patients. In this case, the results significantly correlated with the distance evaluated by 6MWT29. In particular, reproducibility and sensitivity of the 6 min stepper test used in COPD patients were demonstrated30. Considering that it is feasible, reliable, and easy to perform and requires minimal space, the 6MWT should be considered when evaluating the endurance exercise capacity of COPD patients.
Regarding the results of this study, improvement of the arm curl test was similar to a previous study that used 8 weeks of resistance exercise (pre: 10.3 ± 2.4, post: 12.4 ± 2.6) and pulmonary rehabilitation combined with resistance exercise (pre: 10.9 ± 2.5, post: 12.4 ± 2.8) in COPD patients31. The improvement of the sit-to-stand test was also consistent with a previous study that used home- and hospital-based resistance exercise programs32,33. Finally, improvement of the 6MWT achieved minimal clinical significance difference (MCID) of 33 m11. The speculated reason is that many different angles and contraction modes of isometric and isotonic exercise are contained in prescribed pulmonary exercise, which can effectively stimulate muscle contraction and achieve training effects. However, less attention was paid to the effects of TCE on skeletal muscle function in COPD patients; thus, more studies should be conducted to investigate the accurate effects and related mechanisms.
In addition, the limitations include concerns regarding the evaluation of quality of life. Although SGRQ is often used as a COPD-specific questionnaire to speculate prognosis and development of the disease5, the outcome is susceptible to subjective awareness and patients’ level of literacy. Hence, a specialized staff is crucial to the quality of life evaluation. The results in this study showed significantly decreases in SGRQ scores and surpassed the MCID of four scores21. The results are consistent with previous studies that applied tai chi, Liuzijue, Yijinjing, and Baduanjin as interventions in COPD patients16,18,19,34. In addition, a recent meta-analysis found similar improvements in quality of life of COPD patients when home- or hospital-based rehabilitation were applied35.
In conclusion, prescribed pulmonary exercise can be performed in clinics, homes, and in the community to improve the exercise capacity and quality of life in stable COPD patients. Further research is required to fully explore the effectiveness in COPD patients of different severity and the long-term outcomes in stable COPD patients.
The authors have nothing to disclose.
This study was supported by the national fitness project of General Administration of Sport of China (No. 2017B021), the key basic research grants from Science and Technology Commission of Shanghai Municipality (No. 16JC1400500), the directed research grants from Science and Technology Commission of Shanghai Municipality (No. 18DZ1200600), and National Natural Science Foundation of China (No. 81472163).
4643a | Tanita | Used for the evaluation of height, weight, and body mass index | |
Borg CR10 | None | Used for the evaluation of dyapnea | |
PASS 15.0 | NCSS, LLC | Used for power calculation | |
Polar team 2 | Polar | Used for supervising the heart rate of participants | |
SGRQ software | Developed by Peking Union Medical College | Used for calculating the score of quality of life | |
SPSS 24.0 | IBM Corporation | Used for statistical analysis |