Background: Physical activity (PA) in patients with myasthenia gravis (MG) is considered safe and beneficial, and an active lifestyle is required to obtain the health benefits of exercise. However, as the disease leads to physical impairments an insight into the overall PA habits in this patient population is relevant but lacking.

Objective: To measure habitual physical activity in a Danish cohort of patients with MG measured by accelerometer and questionnaire, and to determine relevant predictors for PA intensities.

Methods: Habitual physical activity was assessed by; 1) the accelerometer ActiGraph in a cohort of patients recruited from our neuromuscular clinic, 2) the International Physical Activity Questionnaire (IPAQ) in a web-based survey. PA levels were compared to international recommendations. Predictors for PA (age, sex, body mass index, disease severity and duration) were included in the regression analyses.

Results: Habitual physical activity was measured by accelerometer for 7 days in 69 patients and by questionnaire in 691 patients. Measured by the accelerometer, 46% of the patients did not meet the international recommendations for PA at moderate/vigorous intensity and 57% were below the recommendations for steps per day. Measured by the IPAQ, 48% did not meet the recommendations. Disease severity and age were predictors for PA intensities.

Conclusions: This study found that around half of the included patients did not meet the recommendations for PA. This is a concern, as it increases the risk of life-style related diseases. Disease severity and age may be taking into consideration when counseling the patients about PA.