title: A novel method for using accelerometer data to predict energy expenditure.
abstract: The purpose of this study was to develop a new two-regression model relating Actigraph activity counts to energy expenditure over a wide range of physical activities. Forty-eight participants [age 35 yr (11.4)] performed various activities chosen to represent sedentary, light, moderate, and vigorous intensities. Eighteen activities were split into three routines with each routine being performed by 20 individuals, for a total of 60 tests. Forty-five tests were randomly selected for the development of the new equation, and 15 tests were used to cross-validate the new equation and compare it against already existing equations. During each routine, the participant wore an Actigraph accelerometer on the hip, and oxygen consumption was simultaneously measured by a portable metabolic system. For each activity, the coefficient of variation (CV) for the counts per 10 s was calculated to determine whether the activity was walking/running or some other activity. If the CV was <or=10, then a walk/run regression equation was used, whereas if the CV was >10, a lifestyle/leisure time physical activity regression was used. In the cross-validation group, the mean estimates using the new algorithm (2-regression model with an inactivity threshold) were within 0.75 metabolic equivalents (METs) of measured METs for each of the activities performed (P >or= 0.05), which was a substantial improvement over the single-regression models. The new algorithm is more accurate for the prediction of energy expenditure than currently published regression equations using the Actigraph accelerometer.
authors.affiliation: Department of Exercise, Sport, and Leisure Studies, University of Tennessee, Knoxville, USA. sec62@cornell.edu
authors.forename: Scott E
authors.initials: SE
authors.lastname: Crouter
authors.forename: Kurt G
authors.initials: KG
authors.lastname: Clowers
authors.forename: David R
authors.initials: DR
authors.lastname: Bassett
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000465:Algorithms; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D010101:Oxygen Consumption; D012044:Regression Analysis; D015203:Reproducibility of Results; D012420:Running / Q000502:physiology; D016138:Walking / Q000502:physiology