Physical Inactivity in Pulmonary Sarcoidosis

Purpose
Reduced physical activity in many chronic diseases is consistently associated with increased morbidity. Little is known about physical activity in sarcoidosis. The aim of this study was to objectively assess physical activity in patients with pulmonary sarcoidosis and investigate its relationship with lung function, exercise capacity, symptom burden, and health status.
Methods
Physical activity was assessed over one week in 15 patients with pulmonary sarcoidosis and 14 age-matched healthy controls with a tri-axial accelerometer (ActivPalᵀᴹ) and the International Physical Activity Questionnaire (IPAQ). All participants underwent pulmonary function tests, 6-minute walk test (6MWT) and completed the Fatigue Assessment Scale (FAS), Medical Research Council (MRC) Dyspnoea Scale and the King’s Sarcoidosis Questionnaire (KSQ).
Results
Patients with sarcoidosis had significantly lower daily step counts than healthy controls; mean(SD) 5624(1875) vs. 10429(2942) steps (p<0.01) and completed fewer sit-to-stand transitions each day (p=0.095). Only two patients (13%) self-reported undertaking vigorous physical activity (IPAQ) compared to half of healthy individuals (p<0.01). Daily step count was significantly associated with 6MWT distance in sarcoidosis (r=0.634, p=0.01), but not with forced vital capacity (r=0.290), fatigue (r=0.041), dyspnoea (r=-0.466) or KSQ health status (r=0.099-0.484). Time spent upright was associated with fatigue (r=-0.630, p=0.012) and health status (KSQ Lung scores r=0.524, p=0.045), and there was a significant correlation between the number of sit-to-stand transitions and MRC dyspnoea score (r=-0.527, p=0.044).
Conclusion
Physical activity is significantly reduced in sarcoidosis and is associated with reduced functional exercise capacity (6MWD). Fatigue, exertional symptoms and health status were more closely associated with time spent upright and the number of bouts of physical activity, as compared to step counts. Further studies are warranted to identify the factors that determine different physical activity profiles in sarcoidosis.