The relationship between a direct measure of physical activity against self-reported physical activity, muscle strength, quality of life and exercise capacity in pulmonary sarcoidosis

Background: Sarcoidosis is a diverse condition. The condition currently has a limited body of knowledge surrounding the effect and role of physical activity, diet and exercise on quality of life and disease management. Yet, physical activity is frequently suggested as beneficial within sarcoidosis however little is currently known about physical activity patterns within the condition as well as its role and effect on other key physiological and mental variables. Additionally, self-reported measures such as the IPAQ are regularly utilised within research due to their ease of use and low cost however their validity and accuracy within sarcoidosis in comparison to an objective measure (tri-axial accelerometer) is currently unknown. Methods: A lab-based approach was utilised with participants visiting twice to validate their variable measurements. Participants undertook exercise capacity (6 MWT), lung function (FEV1, FVC, PEF), muscle strength (HGS, QPT, HPT, EFMS), quality of life (SHQ) and fatigue (FAS) tests in addition to wearing a tri-axial accelerometer for five days between visits. Results: Participants recorded above recommended levels of physical activity via the accelerometer (152 mins MVPA per day) and was strongly correlated to self-reported MVPA (0.875, p=0.022) although a large difference was recorded (52 mins per day) between the two methods. Handgrip strength was strongly correlated with gender (0.809), body fat percentage (0.794), elbow flexor muscle strength (0.961) and forced vital capacity (0.865). Conclusions: Physical activity patterns are diverse within sarcoidosis much like the general public, while physical activity‘s relation to other variables appears limited although the variables are multi-faceted. Handgrip strength and six-minute walk distance may be a good indicator of a range of other key variables within the condition.