title: Estimating activity-related energy expenditure under sedentary conditions using a tri-axial seismic accelerometer.
abstract: Activity-related energy expenditure (AEE) is difficult to quantify, especially under sedentary conditions. Here, a model was developed using the detected type of physical activity (PA) and movement intensity (MI), based on a tri-axial seismic accelerometer (DynaPort MiniMod; McRoberts B.V., The Hague, the Netherlands), with energy expenditure for PA as a reference. The relation between AEE (J/min/kg), MI, and the type of PA was determined for standardized PAs as performed in a laboratory including: lying, sitting, standing, and walking. AEE (J/min/kg) was calculated from total energy expenditure (TEE) and sleeping metabolic rate (SMR) as assessed with indirect calorimetry ((TEEx0.9)-SMR). Subsequently, the model was validated over 23-h intervals in a respiration chamber. Subjects were 15 healthy women (age: 22+/-2 years; BMI: 24.0+/-4.0 kg/m2). Predicted AEE in the chamber was significantly related to measured AEE both within (r2=0.81+/-0.06, P<0.00001) and between (r2=0.70, P<0.001) subjects. The explained variation in AEE by the model was higher than the explained variation by MI alone. This shows that a tri-axial seismic accelerometer is a valid tool for estimating AEE under sedentary conditions.
authors.affiliation: Department of Human Biology, Maastricht University, Maastricht, The Netherlands.
authors.forename: Vincent T
authors.initials: VT
authors.lastname: van Hees
authors.forename: Rob C
authors.initials: RC
authors.lastname: van Lummel
authors.forename: Klaas R
authors.initials: KR
authors.lastname: Westerterp
mesh_terms: D000054:Acceleration; D000203:Activities of Daily Living; D000328:Adult; D000465:Algorithms; D001481:Basal Metabolism; D002153:Calorimetry, Indirect; D004734:Energy Metabolism; D004867:Equipment Design; D005260:Female; D006801:Humans; D008954:Models, Biological; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D005082:Physical Exertion; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult