Effects of respiratory muscle training on respiratory function and functional outcomes in patients with myasthenia gravis: a systematic review

Zi-Ting Bi¹Jing-Hua Xiao¹Jing-Xue Wei¹Lang Huang¹Ying-Dong Li²Yue-Mi Zhang²Jian Huang³Chao-Song Luo³Jia-Mei Zhang⁴Yunshan Zhang^1*

• ¹First Affiliated Hospital, Guangxi Medical University, Nanning, China
• ²The Guangxi Zhuang Autonomous Region workers’ Hospital, Nanning, China
• ³Jiangbin Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
• ⁴Guangxi International Zhuang Medicine Hospital, Nanning, China

Background: Respiratory muscle training constitutes a structured regimen aimed at enhancing the functionality of respiratory muscles, but the existing literature is deficient in robust evidence regarding its impact on individuals with myasthenia gravis. This systematic review seeks to investigate the influence of respiratory muscle training on respiratory function and functional outcomes in patients with myasthenia gravis. Methods: A comprehensive search of six prominent databases was conducted without any date restrictions until May 1, 2025, targeting studies that met the inclusion criteria: 1) myasthenia gravis patients with age ≥18 years old, 2) respiratory muscle training includes inspiratory and expiratory muscle training, 3) outcomes on respiratory function, respiratory muscle endurance, pulmonary function tests, and functional outcome, 4) randomised controlled trials, cohort studies, case-control trials, and quasi-controlled study. Two independent reviewers conducted qualification review, extracted data from studies that met the eligibility criteria, and assessed methodological quality and quality level of evidence. Given the limited number of RCTs and significant heterogeneit in participant demography, intervention details, and outcome types, a descriptive synthesis was performed. Results: A total of seven studies fulfilled the eligibility requirements, involving 233 participants with an average age of 57.5 years. Two studies demonstrate good methodological quality, one study exhibits high quality, while four studies reflect a moderate standard of quality. The level of evidence of the trials included in this systematic review was 2 to 4. Five studies showed that respiratory muscle training improved respiratory muscle endurance and functional outcomes in patients with myasthenia gravis (p<0.05). Six studies evaluated MIP, while three studies focused on MEP. Additionally, six studies measured FEV1, and three studies examined PEF and FVC separately. However, the results across these studies have not converged on a unified conclusion. Conclusions: This systematic review indicates that respiratory muscle training has the potential to enhance respiratory muscle endurance and functional outcomes in individuals with myasthenia gravis. Nevertheless, the evidence pertaining to its impact on respiratory muscle strength and pulmonary function is still varied and lacks sufficient robustness.