New strategies of physical activity assessment in cystic fibrosis: a pilot study

Regular physical activity (PA) is a valued part of cystic fibrosis (CF) care. Although the accelerometer, SenseWear Armband (SWA), accurately measures habitual PA in CF, it is mostly used for research purposes. For the first time, we analyzed different methods of measuring PA in daily life by the use of smartphones and other electronic devices such as smartwatch and Fitbit.

Twenty-four stable adults with CF (mean age 37.5 ± 11.5SD yrs.; FEV₁ 58 ± 19% predicted, BMI 22.9 ± 3.2) were studied. Daily PA was monitored for seven consecutive days. All patients wore the accelerometer SWA and at the same time they monitored PA with the electronic device they used routinely. They were allocated into one of four arms according to their device: Smartwatch, Fitbit, Android smartphones and iOS smartphones. PA related measurements included: duration of PA, energy expenditure, number of steps.

There was a good agreement between SWA and Fitbit for number of steps (p = 0.605) and energy expenditure (p = 0.143). iOS smartphones were similar to SWA in monitoring the number of steps (p = 0.911). Significant differences were found between SWA and both Smartwatch and Android smartphones.

Fitbit and iOS smartphones seem to be a valuable approach to monitor daily PA. They provide a good performance to measure step number compared to SWA.