Different methods of measuring physical activity in cystic fibrosis: accelerometer versus new electronic devices

Introduction: Physical activity (PA) and exercise are an important part of cystic fibrosis (CF) care. The accelerometer, SenseWear Armband (SWA), is a validated device and provides an accurate estimate of PA in the free-living environment. As the SWA is primarily for research purposes, different methods of measuring PA in daily practice are required. Aims and Objectives: The aim was to investigate if PA dertermined by smartphones (i.e., accelerometer vs new electronic devices) provides similar information. Methods: Twenty-four consecutive stable adults with CF (17 males, 7 females, mean age 37.5±11.5SD yrs; FEV1 58±19 % predicted, BMI 22.9±3.2) were studied. PA was monitored for seven consecutive days. All patients wore the accelerometer SWA and at the same time they monitored daily activity with the electronic device they used routinely. They were equally divided into four arms according to their device: iOS smartphones, android smartphones, smartwatches and fitbit. PA related measurements included: number of steps, duration of PA, energy expenditure. Results: We found evidence of difference between SWA and both android smartphones and smartwatches for all PA variables (p<0.001). There was no difference between SWA and iOS smartphones to monitor the number of steps (p=0.27). We did not found any difference between SWA and fitbit for number of steps (p=0.52), duration of PA (p=0.29), energy expenditure (p=0.24). Conclusions: iOS smartphone and fitbit seem to be a valuable approach to monitor PA. CF patients should be more motivated to use personal devices to control daily PA. This could be a pragmatic approach to monitor PA levels in clinical practice.