Physical Activity and Sedentary Behaviour in People with Myasthenia Gravis: A Cross-Sectional Study

Background: Despite improvements in the medical management of myasthenia gravis (MG) in recent years, patients continue to report poor health and wellbeing outcomes such as high levels of fatigue, reduced quality of life (QoL), walking limitation and lowered balance confidence. Physical activity has been shown to be associated with these outcomes in other populations, however, there has been limited research in adults with MG. Objective: To describe physical activity and sedentary behaviour in adults with MG and to explore associations between these behaviours and fatigue, QoL, balance confidence and walking limitation. Methods: A self-report online survey was used to assess physical activity, sedentary behaviour, fatigue, QoL, balance confidence and walking limitation in adults with MG. Multiple linear regression was used to examine associations and descriptive statistics were used to analyse participant characteristics, physical activity, and sedentary behaviour. Results: Eighty-five adults with MG were included (mean age 48 +/- 16 years). Over half of participants (n = 53, 62.4%) reported sufficient physical activity to meet public health guidelines. Participants reported an average of 9 h/day of sedentary time (mean 9.0 +/- 3.5). Physical activity and fatigue (R-2 = 0.196), QoL (R-2 = 0.330), walking limitation (R-2 = 0.305) and balance confidence (R-2 = 0.304) were significantly (p < 0.05) and positively correlated, with no associations found for sedentary behaviour. When patterns of physical activity and sedentary behaviour were combined, lower fatigue (R-2 = 0.213), higher QoL (R-2 = 0.364), reduced walking limitation (R-2 = 0.341) and higher balance confidence (R-2 = 0.279) was observed in patients who had greater physical activity levels (> 150 mins/week) and lower sedentary time (< 10 h/day). Conclusions: Higher physical activity and lower sedentary behaviour is associated with favorable health and wellbeing outcomes in adults with MG. Further research is required to ascertain whether these behaviours may be an appropriate target intervention to improve outcomes in this population.