Nationwide estimates of all-cause and cause-specific mortality among individuals with gender dysphoria in Sweden, 2001-2023: a register-based cohort study.

Chronic obstructive pulmonary disease (COPD) is a common, preventable, and treatable yet noncurable heterogeneous lung disease characterized by persistent dysfunction of the airways, alveoli, and pulmonary vasculature, leading to progressively worsening symptoms such as dyspnea, cough, and sputum production []. The global burden of COPD continues to rise, largely attributable to heightened exposure to air pollutants and the progressive aging of the population []. COPD has become a major contributor to the global disease burden and is currently the third leading cause of death worldwide [,]. Epidemiological data indicate that between 1990 and 2019, the growth rates of COPD prevalence and incidence in China were lower than the global average, reflecting notable achievements in COPD prevention and control during this period [,]. However, key indicators, including the age-standardized mortality rate, age-standardized incidence rate, and disability-adjusted life years associated with COPD in China, remain at high levels, likely due to accelerated industrialization, urbanization, and population aging. Based on the research conducted by Academician Chen Wang [], the prevalence of COPD among Chinese adults aged 40 years and older is as high as 13.7%, with an estimated patient population exceeding 100 million. Despite notable progress in prevention and control, COPD remains a major public health challenge in China. Respiratory muscle dysfunction is a key pathological mechanism contributing to respiratory impairment in patients with COPD. Under the combined influence of multiple pathological factors, including pulmonary hyperinflation, increased ventilatory demand, inflammation, and oxidative stress, the primary respiratory muscles, such as the diaphragm and internal intercostal muscles, are subjected to both abnormal mechanical loading and metabolic imbalance. This sustained pathological burden induces microstructural alterations, including muscle fiber type transformation and mitochondrial dysfunction, ultimately leading to muscle atrophy and reductions in muscle strength and endurance [,]. Such alterations not only directly impair the function of the primary respiratory muscles but also indirectly exacerbate dyspnea by diminishing ventilatory reserve capacity. This, in turn, initiates a vicious cycle of worsening dyspnea, activity limitation, and progressive loss of muscle strength, thereby markedly increasing the risk of respiratory failure and systemic sarcopenia [,]. A previous study [] has demonstrated a significant association between respiratory muscle strength and disease progression in COPD. Specifically, in the early stages of the disease (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stages I-II), patients mainly present with respiratory muscle dysfunction, such as weakness of the internal intercostal muscles, while in the advanced stages (GOLD stages III-IV), the function of the primary inspiratory muscles, particularly the diaphragm, becomes significantly impaired []. Therefore, improving respiratory muscle function has become one of the key targets in the clinical rehabilitation of patients with COPD. Clinically, common approaches to improving respiratory muscle function include pharmacological treatment, physical factor therapy, and respiratory muscle strength training. Although evidence from a study [] demonstrating the benefits of targeted training supports the potential of these approaches to improve respiratory muscle function in COPD, it must be acknowledged that their overall impact is substantially limited by inherent methodological shortcomings. Pharmacological interventions, such as carbonic anhydrase inhibitors, while enhancing respiratory drive, may induce or exacerbate respiratory acidosis []. Physical modality therapy requires specialized equipment and professional operation, making clinical applications cumbersome and limiting patient adherence to long-term treatment []. Moreover, improper load control during respiratory muscle strength training may lead to adverse events such as headache, coughing, and muscle pain []. Therefore, there is a need to explore safer, more effective, and better-tolerated respiratory muscle training programs to further alleviate COPD-related symptoms and improve quality of life. In recent years, traditional Chinese health-preserving exercises have been widely used as nonpharmacological interventions in COPD rehabilitation, including Tai Chi, Baduanjin, Wuqinxi, and Yijinjing, which are notable for their simplicity, safety, and minimal risk of adverse effects []. Through a combination of physical movements, breathing regulation, and psychological adjustment, these exercises reflect a holistic rehabilitation concept. Existing studies [-] suggest that such exercises not only improve pulmonary ventilation and respiratory muscle strength in patients with stable COPD but also contribute to enhanced quality of life. Consequently, Chinese exercises ha