What can we learn from the Baduanjin rehabilitation as COVID‐19 treatment?: A narrative review

Abstract Aim To understand Baduanjin rehabilitation therapy in mild COVID‐19 patients. Design A narrative review. Methods A literature search for COVID‐19 and Baduanjin treatments was conducted on Chinese and English electronic databases: China National Knowledge Infrastructure, Wanfang Data, Embase, PubMed, Scopus, Science Direct, Ebscohost, SPORTDiscus and ProQuest. Results Twelve studies on the Baduanjin rehabilitation for COVID‐19 patients have been included. We acknowledged the considerable published research and current clinical practice using Baduanjin for COVID‐19 treatment in the following areas: anxiety, depression, insomnia, lung function rehabilitation, immunity and activity endurance. Conclusion The use of Baduanjin as adjuvant therapy for COVID‐19 patients' rehabilitation is still limited, therefore, more clinical studies are needed to confirm its efficacy.


| BACKG ROU N D
Traditional Chinese medicine (TCM) played an important role in the Hubei Province during the COVID-19 pandemic as it was included in the guideline for COVID-19 diagnosis and treatment in China . TCM therapies, such as Chinese herbal decoction, massage, Guasha-scraping, pressure point application, acupuncture, TCM nursing technology techniques and Baduanjin exercise therapy, were widely used in "fangcang" hospitals, which were set up to block the spread of infection and treat mild patients Yang, Islam, et al., 2020;Yang, Luo, et al., 2020). In a quote, TCM research led by the top respiratory expert, Dr Zhong Nanshan, suggested that the best way to resist diseases was to exercise and improve immunity. Hence, he advocated practising Baduanjin, a medical sports and therapy treasure that originated 800 years ago in the Northern Song Dynasty (Tengxun news, 2020).
Baduanjin is a traditional Chinese low-impact aerobic exercise therapy for enhancing physical and mental health and has been used to rehabilitate COVID-19 patients as an effective and safe therapeutic method (Jing et al., 2018;Ma et al., 2020). This narrative review's objective was to explore the evidence of using Baduanjin exercise rehabilitation to improve the health outcomes of COVID-19 patients.

| THE HE ALTH OUTCOME S DUE TO COVID -19 ISOL ATI ON AND RECOVERY
The sudden outbreak of COVID-19 causes an emotional response of extreme fear and uncertainty in public could affect COVID-19 patients directly or indirectly. Isolation practices may have led to negative social behaviour and mental health even after discharging from the hospital. In recent studies, "long COVID" has been coined to describe people who recovered from COVID-19 but still have lasting symptoms after the clinical onset of the infection, such as anxiety, depression, sleep difficulties, fatigue and muscle weakness (Bellan et al., 2021;Huang et al., 2021).
Considering that huge physical and psychological impact COVID-19 has caused, there is an urgent need for a simple, reliable and feasible treatment to improve the physical and mental health of recovered COVID-19 patients, including medical staff and family members. One such treatment that can often be performed by oneself at home with limited supervision is Baduanjin.

| INTRODUC TI ON TO BADUANJ IN
Baduanjin exercise has been described as a combination of Confucianism, Buddhism and Taoism, known as the "three pillars" of ancient Chinese society's philosophical and religious teachings and TCM (Li, 2015). Therefore, the influence of these teachings has produced a manner in which, when practising Baduanjin, the primary focus is self-regulation. To sense the flow of Qi through the body, the practitioner must clear their mind of all thoughts and concentrate on a specific body location (Chen et al., 2006;Koh, 1982). Baduanjin consists of eight movements, each of which takes 2-3 min to complete, and the whole set of movements lasts about 20 min. During practice, it emphasizes firm yet gentle body and limb movements, guided by a calm mind and awareness of spontaneous breathing to cultivate the coordination between the mind and body (Ng & Tsang, 2009).
The low-intensity nature, relatively comfortable physical posture, and movements of Baduanjin are considered appropriate without fatiguing and aggravating the mild symptoms of COVID-19 patients performing the exercise (Li et al., 2014). In addition, there were no statistically significant adverse events associated with practising Baduanjin in previous studies, such as falls or physical injuries, which suggested that Baduanjin exercise is safe for the public, especially for the elders, which make up most of the COVID-19 patients (Fan et al., 2020).
The rationale for using Baduanjin to treat COVID-19 symptoms, stems from the concept of Qi, which is involved in regulating the body's physiological and pathological mechanisms. Baduanjin rehabilitation is given as an adjuvant mind-body exercise therapy based on regulating Qi movement through the body channels known as the meridians. These meridians are distributed at the surface areas of the limbs and trunk, which are connected to the internal organs.
Hence, Baduanjin exercise is geared towards meridian conditioning, which regulates the physical function and thus promotes disease recovery (Han et al., 2020). Given the impact of COVID-19 on patients' quality of life, mental and physical health, meridian conditioning may improve mental and physical functioning. Baduanjin is seen as a lowcost, convenient and conducive method to rehabilitate patients due to its appeal as a non-invasive method with characteristics of good analgesic effects .
Baduanjin, which translates to "eight pieces of brocade" or "eight silken movements," has eight fundamental fluid movements. The first movement is the "two hands holding up the heavens,", which according to TCM, this form can relieve fatigue and eliminate weariness and also helps to rebuild an erect posture of the chest and back.
The second movement, called "drawing a bow on both sides like shooting an eagle," is believed to enhance the functions of the respiratory and circulatory systems. The third movement, "raising single arms up" is said to regulate the spleen and stomach to strengthen the digestive system and the muscles in the arms and shoulders. The fourth movement, "looking back to treat five strains and seven impairments," is said to help strengthen the neck muscles and stimulate the central nervous system, including preventing cervical-vertebral fatigue. The fifth movement, "shaking head and tail to get out angry" relieves tension in the nervous system and adjusts the spine. The sixth movement, "climbing feet with both hands to strengthen kidney and waist," stretches the waist and strengthens the kidney function. The seventh movement, "clenching fist and glare to increase strength," is believed to improve muscular strength and endurance.
The last movement, "putting hands behind the back and standing tiptoe," helps strengthen the spine's ligaments (Qiu, 2009)

| Inclusion and exclusion criteria
Only original studies such as randomized controlled trials (RCT), pre and post-comparisons, cohort studies and retrospective analyses were included in this review. Other studies such as meta-analyses, meta-syntheses, scoping reviews, narrative reviews, rapid reviews, critical reviews, integrative reviews, guidelines and protocols were excluded. Citations retrieved from the initial database search were excluded if the publications were abstracts, conference proceedings, editorials, letters to editors, research letters or short communication and opinion articles.

| Data extraction
Key items from the included articles, including author (s), year of publication, study design, the number of participants (sample), setting, interventions and main outcomes, were extracted by ZZ. The articles and items were appraised by two investigators (MLYO and XP) based on the inclusion and exclusion criteria. Any disagreements were resolved by consensus in the presence of a third investigator (FZ). The team then critically discussed and approved the data from all the included studies. The process of the literature search and findings is given in Figure 2. The key information is summarized in Table 1.

| RE SULTS
Twelve articles were identified and included in this review's final stage of the screening procedure. One paper was published in English, while the other articles were published in Chinese. All the studies were implemented between January and March 2020, which is during the peak period of COVID-19 outbreak in Wuhan, China.
Six of the studies were conducted in the Wuhan Fangcang hospital, a temporary hospital built for isolation and treatment of COVID-

TA B L E 1 (Continued)
studies, 75%), while two were pre-post comparison studies (16.6%), and one was retrospective analysis (8.4%). The number of participants in the studies ranged from 16 to 120. In this review, the total number of participants was 810. The average sample size of each study was 68.
Twelve studies were included, seven of which only used Baduanjin, and the remaining five combined Baduanjin with other treatments (two are Baduanjin combined with five-element music, the other two are Baduanjin combined with acupoint massage, one is Baduanjin combined with auricular point massage). The duration of the programs ranged from seven to 30 days, and the frequency was between one and four times a day, 5-7 days a week. Each exercise lasted between 20 to 60 min.
From the main findings in Table 1, we found that the main efficacy of Baduanjin on patients with COVID-19 is reflected in four aspects: first, to improve anxiety and depression; second, to relieve the symptoms of dyspnoea. The third is to improve the symptoms of insomnia and sleep quality; the fourth is to strengthen immunity; the fourth is to enhance activity endurance.

| Baduanjin for relieving symptoms of COVID-19 related anxiety and depression
Baduanjin is a COVID-19 rehabilitation exercise method recommended by the Chinese Rehabilitation Society (Wu, 2020a(Wu, , 2020b. It has also been demonstrated to reduce depression and anxiety symptoms in patients with psychosomatic illnesses (Xu, 2020;Zhang et al., 2021), which may be appropriate as an alternative therapy for rehabilitation in COVID-19 patients with these symptoms .
During the outbreak of COVID-19, the nationwide lockdown imposed on the public led to a series of psychosocial problems, such as self-harm, domestic violence or aggression due to lockdown, grieving of family and friends who were infected or died due to COVID-19, separation from family and friends and social isolation (Choi et al., 2020;Taylor, 2019). These conditions led to a higher incidence of anxiety and depression than before the COVID-19 pandemic. One investigation reported that 402 adults surviving COVID-19 had 31% depression and 42% anxiety in Italy (Mazza et al., 2020). Preliminary data suggests that 19% of citizens had depression and 14% had anxiety in Hong Kong during the pandemic (Choi et al., 2020). Adverse emotions such as anxiety and depression have negatively affected the rehabilitation of patients. One study reported that Baduanjin could alleviate the anxiety symptoms of perimenopausal women more than walking exercises (Xiao et al., 2016). Another study identified that Baduanjin is a better method of exercise than jogging in delaying cognitive and physiological function decline in the elderly (Sun & Wang, 2008). Baduanjin has shown a statistically significant effect in improving patients' negative emotions. Xu (2020) (Lee et al., 2021;Wang, 2011). Research has shown that a MET-min/week range of 500 to 1000 is the most beneficial to COVID-19 patients (Lee et al., 2021). These positive effects can be attained when coordination between breathing, body movement and mind is achieved harmoniously after several Baduanjin practice sessions (Yang & Wei, 2012). There are also fewer cognitive demands when practicing Baduanjin. Therefore, it is considered beneficial to the mental health of COVID-19 patients (Han et al., 2020).
Compared to other aerobic exercises, Baduanjin exercise emphasizes slow and deep breathing, a calm mind and circulation of Qi in the body. Baduanjin exercise can coordinate the mind and body by controlling the flow of Qi in the body (Liu et al., 2014;Qi et al., 2018).
It focuses on the mobilization of functional potentialities, making the process of breathing smoother and unifying the mind and body by regulating breathing, thereby promoting the normal circulation of Qi (Zheng et al., 2015). The second movement of Baduanjin is "like shooting from left to right," which helps expand the thorax and mobilize the diaphragm. Subsequently, the range of motion is significantly increased, the diaphragm function is improved, and the vital capacity increases (Qi et al., 2018). Participants felt their bodies relaxed, moods calm, and passive emotions improved after regular Baduanjin training for several weeks (Yang, Islam, et al., 2020;Yang, Luo, et al., 2020).

| Baduanjin for easing COVID-19 related dyspnoea and wheezing symptoms
The chest imaging of moderate-to-severe COVID-19 patients showed multiple fibrous streaks and infiltrating lesions, which may progress to impaired lung function leading to dyspnoea and asthenia . However, radiographic imaging is insensitive to early or mild COVID-19 symptomatic infections, although the disease can be detected and monitored for abnormality or progression using computed tomography (CT) (Rubin et al., 2020). For mild patients, practicing Baduanjin exercise has a positive effect in alleviating the symptoms of dyspnoea and wheezing during the rehabilitation period (Zhang, He, & Li, 2020;Zhang, Lu, et al., 2020;Zhao et al., 2020). Cai et al. (2021) identified Baduanjin as an adjuvant treatment for COVID-19 to significantly improve the patient's shortness of breath symptoms. A study showed that pulmonary function improved after 3 months of Baduanjin intervention in the elderly Zhou et al., (2016) and Chen, Yu, et al. (2020) suggested that Baduanjin exercise could improve the fatigue state of COVID-19 patients and promote recovery. The improved recovery may be attributed to the practice of these Baduanjin exercises: "two hands hold up the heavens," "separate heaven and earth," and "two hands hold the feet to strengthen the kidneys and waist," in which the respiratory rate and depth may be enhanced through the increase in the diaphragm movement (Jing et al., 2018). By performing these particular exercises, the respiratory muscles are trained, thereby increasing lung capacity. Taken together, the combination of breathing movements of the chest and abdominal wall increases the activity of the diaphragm and abdominal muscles, thereby regulating the intercostal muscles and respiratory function, causing a further increase in pulmonary ventilation (Deng & Chen, 2015;Han & Lin, 2016;Zhang, 2012).

| Baduanjin for improving sleep quality in COVID-19 patients
Insomnia is the most notable mental health condition among the affected COVID-19 population, showing a 23.87% prevalence with reports of significantly higher insomnia among healthcare workers than in the general population (Cenat et al., 2020). Killgore et al. (2020) reported that people are experiencing more sleep-related problems due to pandemic-related anxieties in the United States. Additionally, statistical analysis revealed that insomnia severity was greater when associated with pandemic fears and suicidal thinking. Therefore, interventions aimed at improving sleep may be useful in reducing suicide risk during the current pandemic. Yang et al. (2021) described how COVID-19 causes people to feel anxious and uneasy, even causing or aggravating insomnia, particularly in middle-aged and older adults. In China, reports of insomnia in people aged 50 years or over account for 40% of total insomnia, whereas in the 60-90-year-old, the chronic insomnia rate was 90% (Li, 2020). Sleep deprivation will lead to a decline in natural killer (NK) cell activity and immune function. The NK cells are mainly involved in antiviral processes in vivo (Yang & Yu, 2017;Zhang et al., 2016). Therefore, COVID-19 patients with immunodeficiency will experience an increase in dyspnoea and wheezing symptoms, complicating the medical prognosis and subsequently causing a higher risk of death .
Baduanjin can improve sleep disorders by regulating negative emotions, priming immune function and regulating various neurotransmitters (China Association of Acupuncture-Moxibustion, 2020).
Baduanjin exercise is a feasible, safe and effective intervention program for improving sleep quality in community-dwelling older adults with sleep disturbances (Fan et al., 2020). Baduanjin's effect in promoting sleep quality may be due to enhanced levels of serum F I G U R E 3 Medical staff taught Baduanjin to the COVID-19 patients in Jiangxiao fangcang shelter hospital located in Hebei Province, China. Photo courtesy of Yinqin, a frontline nurse, working in the COVID-19 shelter hospital in Wuhan melatonin, an important hormone for regulating sleep-wake rhythm and modulating emotions (Simko et al., 2016). One research reported that Baduanjin exercise combined with ear acupoint stimulation could improve the sleep quality of COVID-19 patients with insomnia, and the effect is better than the oral administration of estazolam . Estazolam medication possesses hypnotic and anti-anxiety effects, but long-term use can cause the suppression of respiration and drug dependence (Zhu & Yin, 2016). Hence, the non-invasive nature of acupoint or pressure point (non-needle) stimulation of specific body areas has been one of the many fundamental treatments of TCM, which complements seamlessly with Baduanjin exercise therapy (Lu et al., 2019).

| Baduanjin for improving the immunity of COVID-19 patients
The immune system is an important defence against diseases.
Immunity in western medicine theory is known as "Positive Qi" in traditional Chinese medicine theory (Wang & Hao, 2020). According to the ancient traditional Chinese internal medicine book Huangdi's Internal Classic or "Huangdi Neijing", written during the period 475-225 BC, it was said that "If Qi is stored in the body, illness cannot occur" (Li, 2015). When the viscera function of the body is normal, the healthy Qi is sufficient, providing a solid and dense external body's immune defence system (first line of defence), thus the concept of "epidemic poison and evil Qi" is said to be presented with a difficult path to invade, and subsequently, the disease will not occur (Yao et al., 2020). peripheral blood (Liang, 2018). In addition, college students practising 16 weeks of Baduanjin showed a statistically significant increase in serum immunoglobulin, IgM, the antibody produced by the adaptive humoral immunity in response to infection .
These results provide strong evidence for Baduanjin to improve human immunity. Cao (2020) described how doctors and nurses led the COVID-19 patients in Wuhan shelter hospital to practice Baduanjin as rehabilitation to promote recovery (Figure 3).

| Baduanjin for improving the physical fitness of COVID-19 patients
Mild COVID-19 patients who are isolated without any form of physical rehabilitation may lead to poor physical fitness. Baduanjin exercise can be practised anywhere, even in a limited space such as the shelter hospital, hence it is suitable for COVID-19 patients during the rehabilitation period. Baduanjin, which combines the "Qigong" theory (work energy) and aerobic exercise, is used as an integrative and complementary therapy in TCM to improve the pulmonary function of COVID-19 patients (Ming, 2017;Wang & Meng, 2016) significantly. A meta-analysis showed that Baduanjin could effectively improve patients' lung function and exercise tolerance or physical fitness, preventing muscle atrophy and inactivity . COVID-19 patients' activity tolerance is closely related to lung function. Previous studies have shown that Baduanjin exercise helps improve pulmonary function, reduce fatigue and improve activity tolerance in mild or convalescent COVID-19 patients (Bi & Guo, 2020;Chen, Yu, et al., 2020;Wu, Pan, et al., 2020;Wu, Shan, & Tang, 2020  recovery, including research on socio-medical aspects such as cultural acceptance and health policies.

AUTH O R CO NTR I B UTI O N S
ZZ conceived the idea, gathered data, provided intellectual content and write the manuscript; XP provided intellectual content and support, appraised articles, wrote the manuscript. JT gathered the data, provided idea and reviewed the manuscript. MLYO provided idea, consultation and intellectual content, appraised articles, and wrote the manuscript; FZ provided idea, resolved disagreements and reviewed the manuscript. All authors approved the final version of the manuscript.

ACK N O WLE D G E M ENTS
The

CO N FLI C T O F I NTE R E S T
There are no other conflicts of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.