Darcy Ummels

General introduction | 11 1 continuously and concurrently measure multiple variables, such as walked distance, heart rate, number of stairs climbed, and time spent in a given position (e.g., sitting). Activity trackers can be divided into three basic categories: pedometers, accelerometers, and apps. Pedometers generally only measure the number of steps, whereas accelerometers can measure more variables such as step count or heart rate. Both pedometers and accelerometers can typically be worn on several places such as the wrist, trouser pocket, and brassiere. Most smartphones and smartwatches include built ‐ in accelerometers. Apps on smartphones and smartwatches can then use this accelerometer and thus require no additional device (e.g., an accelerometer on the wrist), contrary to pedometers and accelerometers. Potential use of activity trackers in healthcare Insight into a patient’s physical activity level aids daily clinical practice for both healthcare professionals and patients, since these data can be used for diagnostic, prognostic, and evaluative purposes. 37 Clinical practice guidelines advise healthcare professionals, such as physiotherapists, to measure the physical activity level of their patients, most of whom are older adults or people with a chronic disease, with questionnaires and diaries. 38 ‐ 43 Activity trackers can serve as an alternative or supplement to such measurement tools. In particular, consumer ‐ grade activity trackers have potential, since they tend to be easy ‐ to ‐ use for both healthcare professionals and patients and, unlike non ‐ consumer ‐ grade activity trackers, do not require additional licenses or software costs. Consumer ‐ grade activity trackers can offer objective insight into patients’ physical activity level and could potentially support the clinical reasoning of healthcare professionals. Next to that, studies have shown that the use of activity trackers can enhance patients’ self ‐ management and self ‐ efficacy. 44,45 Self ‐ monitoring could also lead to improved patient’s coping, realistic goal setting, and improved quality of life. 46 Furthermore, using activity trackers in combination with regular exercise or life ‐ style guidance has been shown to improve the physical activity level of patients with a chronic disease and older adults. 47 ‐ 50 Healthcare professionals, such as physiotherapists, 51 nurses, 52 nutritionists, 53 and general practitioners, 54 are trained to provide lifestyle guidance. Hence, there are abundant advantages to integrating activity trackers into healthcare, yet they are seldom used. Validity of activity trackers in older adults and people with a chronic disease Several validity and reliability studies of consumer ‐ grade activity trackers have been performed in healthy adults. 55 ‐ 57 A systematic review showed that they offer good validity for step count, a lower validity for energy and sleep, and a high reliability for step