Wearable Device Validity in Measuring Steps, Energy Expenditure, and Heart Rate Across Age, Gender, and Body Mass Index: Data Analysis From a Systematic Review.

Background: This paper examined whether the criterion validity of step count (SC), energy expenditure (EE), and heart rate (HR) varied across studies depending on the average age, body mass index (BMI), and predominant gender of participants.

Methods: Data from 1536 studies examining the validity of various wearable devices were used. Separate multilevel regression models examined the associations among age, gender, and BMI with device criterion validity assessed using mean absolute percent error (MAPE) at the study level.