Effects of traditional Chinese eight brocade exercise with same frequency and different durations on the quality of life, 6-min walk and brain natriuretic peptide in patients with chronic heart failure

Background: Traditional Chinese eight brocade exercise (TCEBE) with same cycle and frequency and different durations has an effect on patients with chronic heart failure (CHF). However, relevant reports on the topic are lacking. Objective: This study aims to explore the differences of rehabilitation effect by conducting TCEBE with the same cycle and frequency and different single exercise time for patients with CHF. Methods: A total of 103 patients with CHF were randomly divided into long-time group (LTG), short-time group (STG) and control group (CG). The subjects in the three groups were given corresponding routine treatment. In addition, under the guidance of professional TCEBE coaches and nurses, TCEBE was conducted for 12 weeks (3 times/week) for LTG (60 min/time) and STG (30 min/time). Minnesota living with heart failure questionnaire (MLHFQ) was used, and 6-min walk (6MWK) and brain nautical peptide (BNP) were tested. Results: 1) At 12 weeks, the comparison between groups obtained the following results: For the LTG, MLHFQ was less than that of the CG (P < 0.01), 6MWT was greater than that of the CG (P < 0.05), and 6MWT was greater than that of the STG (P < 0.05); for the STG, MLHFQ was less than that of the CG (P < 0.05); no significant difference in BNP was found among the three groups; 2) At 12 weeks and 0 weeks, the comparison obtained the following results: For the LTG, MLHFQ decreased by 37.7 %, and 6MWT increased by 46.7 % (P < 0.01); for the STG, MLHFQ decreased by 31.7 %, and 6MWT increased by 31.5 % (P < 0.01); for the CG, MLHFQ decreased by 14.6 %, and 6MWT increased by 19.7 % (P < 0.05); no significant change in BNP was found in each group. Conclusion: TCEBE of two kinds of duration improves the quality of life and 6MWT of patients with CHF but has no positive effect on BNP. Compared with 30-min/time, 60-min/time further improves 6MWT in patients with CHF but has no additional benefit on quality of life.


Introduction
Chronic heart failure (CHF) is a group of clinical syndromes caused by various aetiologies, such as cardiac diastolic and systolic dysfunction, venous system congestion, arterial system hypoperfusion and secondary neurohormonal activation (McDonagh et al., 2021;Moradi et al., 2020;Jones et al., 2019). Most patients have dyspnoea, fatigue, fluid storage and reduced exercise tolerance (Seferovic et al., 2019;Hersberger et al., 2021;Veenis et al., 2020), and their quality of life is seriously affected (Agostoni and Dumitrescu, 2019;Wiśnicka et al., 2022). Physical exercise can improve exercise tolerance, improve the symptoms of patients with CHF and reduce mortality and rehospitalisation rate (Taylor et al., 2019a;Taylor et al., 2019b;Sties et al., 2018).
Traditional Chinese eight brocade exercise (TCEBE) is a traditional rehabilitation exercise recommended by the General Administration of Sport of China (Zou et al., 2020). It includes eight simple, slow and relaxing movements. Its movements are simple and easy to learn (He, 2021). In addition, it pays attention to the extension of trunk and limbs and the coordination of nerve and muscle (Sheng, 2020). It is a suitable exercise for middle-aged and elderly people (Zou et al., 2020;He, 2021;Sheng, 2020). Previous studies have suggested that regular TCEBE has a positive effect on patients with CHF (Yao et al., 2021;Li et al., 2019;Li et al., 2021). However, to the best of our knowledge, no literature has reported on the effect of TCEBE with the same frequency and different exercise duration on patients with CHF. Whether the length of a single exercise affects the exercise effect is worth exploring.
Therefore, this study conducted TCEBE with the same frequency and different durations of single exercise for patients with CHF to explore its rehabilitation effect. This study could serve as reference for designing TCEBE prescription for patients with CHF. This study hypothesised that TCEBE with the same frequency (12 weeks, 3 times/week) and different exercise durations (30 and 60 min/time) has a positive effect on the quality of life, 6-min walk (6MWK) and brain nautical peptide (BNP) of patients with CHF. Moreover, the longer the duration of a single exercise, the more evident the effect.

Participants
This study was approved by the Human Experimental Ethics Committee of Chengdu Aeronautic Polytechnic (No. 202108). Patients with CHF who were hospitalized in Affiliated Sport Hospital of Chengdu Sport University from March 2021 to January 2022 were recruited. Inclusion criteria were as follows: (1) ≥60 years old; (2) meets the diagnostic criteria of CHF, NYHA cardiac function grade II-III (Yancy et al., 2013); (3) patients admitted on foot; (4) study is in accordance with the Declaration of Helsinki, and informed consent was signed. Exclusion criteria include the following: (1) movement obstacle, (2) unstable angina pectoris or acute myocardial infarction, (3) cognitive impairment and (4) other diseases prohibited from exercise.
In reference to a previous intervention scheme of TCEBE for patients with CHF (Hong, 2020;Tang, 2019), this experiment is 3 (number of groups) × 2 (number of measurements) and has a sample loss rate of about 15 %. G-Power software was used for calculation. Effect size was set to 0.3, and power was set to 0.8. Level α was set to 0.05, and at least 99 samples were calculated. A total of 120 patients who met the diagnosis and inclusion criteria were divided into long-time group (LTG), short-time group (STG) and control group (CG) by digital random allocation. At the beginning of the experiment, LTG had six patients, STG had five patients, and CG had six patients who withdrew due to personal reasons. The sample loss rate was 14.2 %. Finally, 103 subjects completed the entire experimental process. Among them, 34 cases belonged to the LTG (male/female: 15/19), 35 cases belonged to the STG (male/female: 16/19), and 34 cases belonged to the CG (male/female: 14/20). No significant difference in baseline data was found among the three groups (P > 0.05) ( Table 1).

Traditional Chinese eight brocade exercise
Firstly, the subjects in the three groups were given corresponding drug treatment, such as condition observation, oxygen inhalation, dietary care, psychological care, medication guidance, according to the routine. On this basis, patients in CG were guided to take proper activities and rest, patients with cardiac function level III can take proper bedside activities and self-care, and patients with cardiac function level II can take appropriate outdoor walks (Taylor et al., 2019a;Taylor et al., 2019b).
Secondly, LTG and STG were trained for 12 weeks under the guidance of professional TCEBE coaches and nurses. Introduction to TCEBE includes the following routines: (1) holding the hands high with palms up to regulate the internal organs, (2) posing as a shooting archer with the left and right hands, (3) holding one arm aloft to regulate the functions of the spleen and stomach, (4) looking backwards to prevent sickness and strain, (5) swinging the head and lowering the body to relieve stress, (6) moving the hands down the back and legs and touching the feet to strengthen the kidneys, (7) thrusting the fists and making the eyes glare to enhance strength and (8) raising and lowering the heels to cure diseases (Zou et al., 2020;He, 2021). Chen et al. (2020) studied TCEBE in the elderly and found that the relative oxygen consumption and heart rate were 44 % and 67 % of the exercise cardiopulmonary function test, respectively, and the average energy consumption was (23.3 ± 4.4) kcal, indicating that TCEBE is a moderate-intensity aerobic exercise.
For LTG (3 times/week, 60 min/time) and STG (3 times/week, 30 min/time), the first 2 weeks were the movement learning period, and the last 10 weeks were the movement consolidation and strengthening period. LTG and STG had 5 min of warm-up and relaxation time before and after TCEBE practice (not counting the TCEBE practice time), and the exercise time was arranged from 7:00 am to 8:30 am. During exercise, each subject was required to wear an exercise bracelet (Honour Aragorn-B19), connect to the computer through Bluetooth and monitor the exercise intensity according to the heart rate (55 %-70 % maximum heart rate) (Cheng et al., 2021a;Cheng et al., 2021b). During the process of exercise, one of the following situations needs to rest in time: >70 % of the maximum heart rate; symptoms include chest pain, shortness of breath, dizziness, cold sweat, nausea and vomiting. All the subjects were interviewed by telephone or face to face every week. During this period, subjects did not perform other forms of exercise (Cheng et al., 2021b;Cheng et al., 2022a).

Indicator testing
The following tests were performed at admission (baseline) and discharge (12 weeks). Quality of life was assessed using the Minnesota Living with Heart Failure Questionnaire (MLHFQ). This scale is composed of 21 subcategories, and each option adopts the Likert scoring method, with a full score of 105. The higher the score, the worse the quality of life (Rector and Cohn, 2004). For the elderly in China, Cronbach's α is between 0.73 and 0.93 (Cong et al., 2022).
For 6MWT assessment, the following procedure was conducted: In an outdoor 50-m closed corridor, the subjects walked back and forth. The timer was set to 6 min. The subjects were allowed to slow down and stop for rest when necessary. Nevertheless, the experimenters encouraged the subjects to continue walking as much as possible. The time was announced once every 1 min, and the subject was informed of the time again 15 s before 6 min. When the time was over, the subject stopped at the same place, and the total walking distance of the subject was measured in m. A 6-min walking distance of <150 m indicates severe CHF, 150-425 m indicates moderate CHF, and 426-550 m suggests mild CHF (Giannitsi et al., 2019).
For BNP assessment, the procedure was conducted as follows: Peripheral venous blood was drawn to measure BNP level. The BNP reagent introduced by Abbott company was determined on an AxSYM instrument by double monoclonal antibody and microparticle enzyme immunoassay.

Statistical analysis
SPSS 20 was used to process the measured data with mean ± standard deviation, and two-way ANOVA was conducted to determine whether interaction existed between time (2) and group (3). In case of interaction, one-way ANOVA was used to analyse the differences within the group and between the groups afterwards; if no interaction was observed, paired sample t-test was used for comparison at different time points within the group, and one-way ANOVA was used for comparison at the same time point between the groups. The post hoc comparison was adjusted by Bonferroni to ensure that the overall type I rate of each ANOVA was not >0.05 (Cheng et al., 2022b). α = 0.05 as considered statistically significant. Table 2 shows the two test results of the three groups of subjects. Firstly, two-way ANOVA was used to analyse whether interaction existed between time (2) and group (3). No interaction was observed between MLHFQ (F = 0.077, P = 0.962), 6MWT (F = 0.760, P = 0.514), BNP (F = 0.092, P = 0.886) time and group (P > 0.05). Therefore, paired sample t-test was used for comparison at different time points within the group, and one-way ANOVA was used for comparison at the same time point between the groups. Bonferroni adjustment was used for post hoc comparison.
At the end of intervention (12 weeks), the three groups were compared. BNP (F = 0.577, P = 0.610) had no significant difference between the groups (P > 0.05). The difference between MLHFQ (F = 7.865) and 6MWT (F = 11.706) was statistically significant (P < 0.05). Furthermore, Bonferroni comparison between the groups showed the following results: (1) for LTG, MLHFQ was less than that of CG (P < 0.01), the difference between 6MWT and CG was statistically significant (P < 0.05), the difference between 6MWT and STG was statistically significant (P < 0.05), and the difference between MLHFQ and STG was not statistically significant (P > 0.05); (2) for STG, MLHFQ was less than that of CG, and the difference was statistically significant (P < 0.05). No significant difference was found between 6MWT and CG (P > 0.05).

Discussion
This study aimed to explore the rehabilitation effect of TCEBE with the same frequency (12 weeks, 3 times/week) and single different exercise duration (30 and 60 min/time) on patients with CHF. The study could serves as a reference for designing TCEBE prescription for patients with CHF. This study validated some of the hypotheses. Firstly, TCEBE of both durations improved the quality of life and 6MWT of patients with CHF but had no positive effect on BNP. Secondly, compared with 30 min/time of exercise, a longer single exercise time of 60 min/time further improved 6MWT in patients with CHF but had no additional benefit on quality of life.

Quality of life of patients with CHF
This study found that under the fixed exercise cycle (12 weeks) and frequency (3 times/week), TCEBE, whether 30 or 60 min/time, improved the quality of life of patients with CHF to varying degrees. Previous studies mainly explored the change of TCEBE cycle and its effect on the quality of life of patients with CHF. Four weeks of TCEBE can cause positive changes in the quality of life of patients with CHF (Lu et al., 2020). Chen et al. (2018) found that compared with 4-and 8-week intervention, 12-week TCEBE significantly improved the quality of life of patients with CHF. Meta-analysis showed that TCEBE at 12-48 weeks decreased the MLHFQ score and improved quality of life in patients with CHF (Yao et al., 2021). These studies (Yao et al., 2021;Lu et al., 2020;Chen et al., 2018) support the results of the present study to a certain extent. The quality of life of patients with CHF was not further improved with the length of single exercise, indicating that the extension of single exercise time has no additional benefit for the improvement of the quality of life of patients with CHF. Our analysis may be related to the insufficient exercise cycle. This study provides some reference for the design of TCEBE prescription to improve the quality of life of patients with CHF.
Chinese medicine believes that the deficiency of Qi and Yang, blood stasis, stoppage of drinking and phlegm resistance are the main pathogenesis of CHF (Tang, 2019). TCEBE is simple and easy to learn and has a remarkable effect on strengthening the human body's physique and regulating the movement of Qi and blood of various viscera and meridians (Zou et al., 2020;He, 2021). This may be related to TCEBE improving dyspnoea symptoms; improving activity endurance; improving sleep; and alleviating anxiety, depression and other emotions in patients with CHF (Yao et al., 2021;Li et al., 2019;Li et al., 2021). TCEBE can reduce the heart load and improve the ability of oxygen transport and utilisation in the blood circulation of the human body, thereby reducing the oxygen consumption of the myocardium and alleviating the dyspnoea symptoms of CHF (Chen et al., 2020), eventually improving the quality of life of patients with CHF.

6MWT in patients with CHF
This study found that under the condition of fixed exercise cycle and frequency, 30-and 60-min/time TCEBE improved the 6MWT of patients with CHF to varying degrees. 6MWT has certain predictive value for daily activities, mortality and survival rate of patients with CHF. The crucial symptoms of clinically stable patients with CHF include decreased exercise endurance (Chen et al., 2018). The study showed that the average metabolic equivalent of TCEBE was 3.96 ± 1.17, suggesting Note: MLHFQ: Minnesota Living with Heart Failure Questionnaire; 6MWT: 6 Minutes Walk; BNP: Brain Natriuretic Peptide. Intra-group comparison at 0 weeks and 12 weeks: a is P < 0.05, A is P < 0.01; After 12 weeks of intervention, Long-time group and Short-time group were each compared with the Control group: b is P < 0.05, B is P < 0.01; Long-time group compared with the Short-time groupt the same timepoint, c is P < 0.05.
that the exercise mode is of medium intensity (Xiong et al., 2015). After 12 weeks (Xiong et al., 2015) and 1 year (Chen et al., 2018) of TCEBE for patients with CHF, 6MWT significantly increased. Furthermore, metaanalysis results showed that TCEBE prolonged the 6MWT of patients with CHF compared with the CG (Yao et al., 2021). This study found that the 6MWT of patients with CHF was further improved with the increase in the duration of a single exercise. This result shows that the extension of single exercise time has additional benefits for the exercise ability of patients with CHF. This may be related to TCEBE characteristics. During exercise, maintaining soft and steady lower limb movements, which increase the endurance of lower limb skeletal muscle, enhance the strength of muscle fibres, improve the perfusion and metabolism of muscles, improve the aerobic metabolic capacity of muscles and increase the tolerance of the body to exercise, is emphasised (Wang et al., 2016). In addition, abdominal breathing is mainly used in TCEBE. Deep and long abdominal breathing can slow down the respiratory rate, enhance the muscle strength of the inspiratory muscle, increase the range of diaphragm movement, increase the maximum ventilation, reduce residual air volume, improve the hypoxia state during exercise and increase the tolerance to exercise; these benefits indicate the improvement of exercise ability (Ge et al., 2017).

BNP of patients with CHF
This study found that 12-week TCEBE intervention, whether 30 or 60 min/time, did not reduce BNP levels in patients with CHF. This result may be related to the short exercise cycle of the patients. The study period included in this study as 12 weeks, which may not be enough to make a considerable change in the serum BNP of patients with CHF.
Meta-analysis (Yao et al., 2021;Li et al., 2019) found that 12-month TCEBE intervention improved the BNP level of patients with CHF, indicating that the exercise cycle may influence the exercise effect. BNP is one of the indicators for the diagnosis and prognosis of CHF. Cardiac neurohormone excreted by cardiomyocytes and excessive pressure load stimulate the ventricular secretion of BNP, and its level is positively correlated with the classification of cardiac function of patients (Merkaš et al., 2021). In addition, evidence shows that exercise training in patients with CHF mainly affects peripheral muscles, thus improving body function and may not have a considerable effect on serum BNP (Kokkinos et al., 2000). Other studies have shown that although exercise training can effectively improve 6MWT in patients with CHF, it will not affect the serum BNP level (Arad et al., 2008). These findings are consistent with the results of the present study.
The present study has some limitations. Firstly, according to the NYHA cardiac function classification of patients with CHF, exploring the effect of TCEBE intervention may ignore the effect of exercise on different CHF phenotypes. Secondly, the exercise cycle is short, and only the short-term effect data of exercise on the quality of life, 6MWT and BNP of patients with CHF can be obtained. The long-term effect needs further study. Lastly, in the follow-up study of the mechanism of TCEBE intervention in heart failure, further attention must be paid to the establishment of the optimal exercise rehabilitation program and the tracking of long-term exercise effects.

Conclusions
Our results showed that under the premise of the same cycle and exercise frequency, TCEBE of both durations improved the quality of life and 6MWT of patients with CHF but had no positive effect on BNP. Compared with 30-min/time exercise, 60-min/time exercise further improved the 6MWT of patients with CHF but did not improve the quality of life.

Submission statement
The data reported in this manuscript have not been published elsewhere and the manuscript is not under consideration for publication in another journal.

Declaration of competing interest
The authors declare that there is no conflict of interest.