Abstract: The pairing of dynamical systems theory and complexity science brings novel concepts and methods to the study of infant motor development. Accordingly, this longitudinal case study presents a new approach to characterizing the dynamics of infant limb and vocalization behaviors. A single infant's vocalizations and limb movements were recorded ...
Abstract: Simple methods to quantify ground reaction forces (GRFs) outside a laboratory setting are needed to understand daily loading sustained by the body. Here, we present methods to estimate peak vertical GRF (pGRFvert) and peak braking GRF (pGRFbrake) in adults using raw hip activity monitor (AM) acceleration data. The purpose ...
Abstract: Accelerometer step count accuracy may be affected by gait speed, device positioning, and analysis algorithm selection. We assessed ActiGraph GT3X+ step count accuracy related to device placement and analysis algorithm in older adults with walking aids (n = 13) and without walking aids (n = 22). Participants (81.5 ± 5.0 years of age) completed a ...
Purpose: Data comparability is an important question in longitudinal studies using different models of accelerometers to measure physical activity. Although studies have been done with adults to compare 7164 and GT3X+ Actigraph accelerometers, comparability in youth has not been demonstrated. The purpose of this study was to determine whether the 7164 ...
Purpose: The aim of this study was to compare common reduction algorithms for ActiGraph accelerometer data using three software packages in order to identify their impact on the number of subjects with valid data. Methods: 200 adolescents from the UP&DOWN Study wore the GT1M and GT3X ActiGraph ...
Purpose: This study aims to establish evidence-based accelerometer data reduction criteria to accurately assess sedentary patterns in children. We not only examined total sedentary time, but also duration and number of breaks and uninterrupted sedentary bouts. Methods: Participants (n=1057 European children; aged 10-12 yrs) wore an ActiGraph accelerometer for at ...
Purpose: Use of accelerometers in research studies has increased over the past 25 years. The first accelerometer, the Caltrac, was worn on the waist and estimated physical activity EE (kcal). Subsequently, the emphasis shifted to measuring minutes of moderate-to-vigorous PA (MVPA) done in 10-min bouts. However, light PA and intermittent MVPA ...
Background: Multiple cutpoints exist for reducing raw accelerometry data into specific intensity categories (i.e. light, moderate, and vigorous). Historically, Freedson et al. (1998) uniaxial cutpoints have been most readily used. Multiple triaxial cutpoints now exist, but no standard interpretation methods have been accepted. Theoretically, using different interpretation methods may ...
Background: A recent technological advancement in accelerometers has enabled the researchers to examine the cadence (i.e., steps/minute) in a free-living environment, which can be used to quantify the intensity of walking activity (i.e., peak cadence). However, little is known about the optimal measurement conditions (i.e., the ...
Background: Cut-points for physical activity intensity are developed from the relationship between oxygen uptake (VO2) and rate of activity counts determined with accelerometry. This practice assumes that the relationship between VO2 and activity-count rate is stable within people, but this has not been directly examined. Purpose: To examine whether the ...