Science News: Free-Living Physical Activity and Sedentary Behavior in Autoimmune Myasthenia Gravis: A Cross-Sectional Study

Submitted by: Pritikanta Paul, MD
Edited by: Milvia Y. Pleitez, MD

Birnbaum S, Bachasson D, Sharshar T, Porcher R, Hogrel JY, Portero P. Free-living physical activity and sedentary behaviour in autoimmune myasthenia gravis: A cross-sectional study. J Neuromuscul Dis. 2021;8(4):689-697. doi:10.3233/JND-210637

Summary: Physical activity in patients with myasthenia gravis (MG) can be limited due to fatigability and undertreated disease. However, patients with well controlled disease are recommended to participate in routine daily exercise to reduce risk of life-style related conditions.
 
This prospective cross-sectional study looked at physical activity patterns of women with MG. Free living physical activity (PA) and sedentary behavior (SB) were quantified using accelerometer device which study participants wore during waking hours for 7 consecutive days. PA was also graded based on level of intensity. Additionally, disease control was assessed by MG-specific evaluations and 6-minute walk test. Control data were obtained from manufacturer database from individuals without self-reported disease.
 
Data analysis included 33 MG patients and 66 controls. Patients with MG were more sedentary than control subjects and performed less vigorous intensity PA, less moderate-to-vigorous intensity PA (MVPA) and shorter duration of MVPA. Interestingly, there was no association between symptom severity, disease duration or lower limb strength with daily PA or sedentary behavior. However, negative correlation of BMI with SB and positive correlation of BMI with daily PA was noted highlighting how chronic steroid treatment may interfere with daily PA by causing weight gain. Overall, patients with stable MG participate in lesser PA compared to controls. Further studies may help understand the influencing factors and build strategies for the same.

Comments: This is an interesting study looking at physical activity patterns of MG patients with relatively controlled disease. Myasthenia gravis is a treatable condition where patients can live a normal to near-normal daily life with adequate disease control. However, physical activity should be encouraged to prevent life-style related comorbidities. This study highlights the importance of looking into different factors which may be influencing PA activity patterns in stable MG patients.

Article of Similar Interest: Andersen LK, Vissing J. Habitual physical activity in patients with myasthenia gravis assessed by accelerometry and questionnaire. J Neuromuscul Dis. 2022;9(1):161-169. doi:10.3233/JND-210693