Calibrating and validating accelerometry for use across early childhood (6-24 months) - Project Summary Accelerometry is standard for objectively measuring physical activity, yet there is surprisingly limited data for best practices when using accelerometry during early childhood, before the age of 2 years. Hip-based accelerometry may be uncomfortable for infants and toddlers particularly during periods of sleep, thus reducing compliance and limiting integrated 24-hour measurements. Wearing the device at the ankle may overcome such limitations, yet data on the performance of ankle-based accelerometry to classify physical activity intensity during early childhood is sparse. One study supports the validity of ankle-based accelerometry among toddlers as young as 14 months, yet the approach has yet to be replicated by an independent research group. Furthermore, data to calibrate physical activity intensity via accelerometry among mobile yet pre-ambulatory infants are lacking. Our long-term goal is to develop obesity-prevention interventions targeting physical activity and sleep during early childhood for families in our rural communities. The goal of this project is to assess the validity of ankle-based accelerometry in measuring physical activity among 6-24-month-olds, a critical stage to support developing physical activity behaviors. Our rationale is to provide a valid method to measure children’s 24-hour movement and sleep with one device over a multiple-day assessment with minimal burden on parents and children. Our specific aims are to 1) Calibrate and validate algorithms to classify physical activity intensity for pre-ambulatory and ambulatory infants and toddlers (6-24 months old) using ankle- and hip-based accelerometry and compare the performance between the two wear sites, and 2) Assess the feasibility of the wear protocol and classification of physical activity intensity for ankle- versus hip-based accelerometry among 6-24-month-olds during a multiple-day assessment in their natural settings. Both aims will use the ActiGraph GT3X+ accelerometer. In the first aim, children will be encouraged to engage in a series of semi-structured activities of varying intensities while wearing two accelerometers, one at the ankle and one at the hip. We will calibrate both devices against direct observation and assess the relative performance of each. In aim 2, another sample of 6-24-month-olds will be asked to wear an accelerometer at the ankle and hip continuously over four days in their natural settings, and we will compare parent satisfaction, compliance with the wear protocol, and estimates of daily physical activity intensity across the two wear sites. This proposed research is innovative, in our opinion, because it focuses on the possibility of ankle-based accelerometry to measure physical activity intensity during the early childhood stage and aims to classify physical activity intensity using accelerometry data for pre-ambulatory infants. This proposed research is significant because it will provide critical data needed to inform best practices for accelerometry for this age group and may facilitate integrated measurements of physical activity and sleep over 24-hours via ankle-based accelerometry.
