Research Database

Actigraphy-based sleep estimation in adolescents and adults: a comparison with polysomnography using two scoring algorithms

  • Published on Jan 18, 2018

Objectives: Actigraphy is widely used to estimate sleep-wake time, despite limited information regarding the comparability of different devices and algorithms. We compared estimates of sleep-wake times determined by two wrist actigraphs (GT3X+ versus Actiwatch Spectrum [AWS]) to in-home polysomnography (PSG), using two algorithms (Sadeh and Cole-Kripke) for the GT3...


Correlates of accelerometer-assessed physical activity and sedentary time among adults with type 2 diabetes

  • Published on Nov 9, 2017

Objectives: The aims of this study were to describe the volume and patterns of objectively assessed sedentary behavior, light intensity physical activity (LPA) and moderate-vigorous physical activity (MVPA), and to examine socio-demographic correlates, among adults living with type 2 diabetes. Methods: Participants (n = 166) wore an accelerometer (Actigraph® GT3X+) for seven ...


Effect of ActiGraph’s low frequency extension for estimating steps and physical activity intensity

  • Published on Nov 20, 2017

Abstract: This study examined the effects of the ActiGraph's (AG) low-frequency extension (LFE) filter on steps and physical activity classification in the free-living environment. Thirty-four African-American women (age, 24.5±5.2 years; BMI, 24.9±4.5 kg/m2) had daily activity measured simultaneously with an AG-GT3X+ accelerometer and a New Lifestyles NL-800 pedometer for seven ...



Using Bluetooth proximity sensing to determine where office workers spend time at work

  • Published on Mar 7, 2018

Background: Most wearable devices that measure movement in workplaces cannot determine the context in which people spend time. This study examined the accuracy of Bluetooth sensing (10-second intervals) via the ActiGraph GT9X Link monitor to determine location in an office setting, using two simple, bespoke algorithms. Methods: For one ...


Estimating Energy Expenditure with ActiGraph GT9X Inertial Measurement Unit.

  • Published on May 2018

Purpose: The purpose of this study was to explore whether gyroscope and magnetometer data from the ActiGraph GT9X improved accelerometer-based predictions of energy expenditure (EE). Methods: Thirty participants (mean ± SD: age, 23.0 ± 2.3 yr; body mass index, 25.2 ± 3.9 kg·m) volunteered to complete the study. Participants wore five GT9X monitors (right ...



Measurement of Active and Sedentary Behavior in Context of Large Epidemiologic Studies

  • Published on Feb 2018

Introduction/Purpose: To assess the utility of measurement methods that may be more accurate and precise than traditional questionnaire-based estimates of habitual physical activity and sedentary behavior we compared the measurement properties of a past year questionnaire (AARP) and more comprehensive measures: an internet-based 24-h recall (ACT24), and a variety ...


Association between physical activity in daily life and pulmonary function in adult smokers

  • Published on Apr 2016

Objective: To determine whether the level of physical activity in daily life (PADL) is associated with pulmonary function in adult smokers. Methods: We selected 62 adult smokers from among the participants of an epidemiological study conducted in the city of Santos, Brazil. The subjects underwent forced spirometry for pulmonary function assessment. ...