Assessment of physical activity and energy expenditure by GPS combined with accelerometry in real-life conditions.
BACKGROUND
Physical activity (PA) and related energy expenditure (EE) is often assessed by means of a single technique. Because of inherent limitations, single techniques may not allow for an accurate assessment both PA and related EE. The aim of this study was to develop a model to accurately assess common PA types and durations and thus EE in free-living conditions, combining data from global positioning system (GPS) and 2 accelerometers.


METHODS
Forty-one volunteers participated in the study. First, a model was developed and adjusted to measured EE with a first group of subjects (Protocol I, n = 12) who performed 6 structured and supervised PA. Then, the model was validated over 2 experimental phases with 2 groups (n = 12 and n = 17) performing scheduled (Protocol I) and spontaneous common activities in real-life condition (Protocol II). Predicted EE was compared with actual EE as measured by portable indirect calorimetry.


RESULTS
In protocol I, performed PA types could be recognized with little error. The duration of each PA type could be predicted with an accuracy below 1 minute. Measured and predicted EE were strongly associated (r = .97, P < .001).


CONCLUSIONS
Combining GPS and 2 accelerometers allows for an accurate assessment of PA and EE in free-living situations.
Dept of Cell Biology and Morphology, Lausanne University, Lausanne, Switzerland.
Dac Minh Tuan
DM
Nguyen
Virgile
V
Lecoultre
Yoshiyuki
Y
Sunami
Yves
Y
Schutz
D061725:Accelerometry; D000328:Adult; D002153:Calorimetry, Indirect; D004734:Energy Metabolism; D005260:Female; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D009043:Motor Activity; D011237:Predictive Value of Tests; D012044:Regression Analysis; D015203:Reproducibility of Results