Assessment of Daily Physical Activity With Accelerometers, an Evaluation Against Doubly Labeled Water

The complex nature of physical activity makes it difficult to accurately measure its aspects and assess the impact on outcome parameters like energy expenditure. Here, the focus was on the ability of different accelerometers to assess daily physical activity as compared with the doubly labeled water technique, which is considered the golden standard to measure energy expenditure under free-living conditions. Six different accelerometers were identified: Lifecorder; Tritrac-R3D; Caltrac; Actigraph/CSA/MTI; Actiwatch AW16; and Tracmor. Many accelerometers have been tested under laboratory conditions during standardized activities, in field settings against portable calorimeters or in the controlled environment of a whole room calorimeter. Most accelerometers show good to very good correlations (r = 0.74 – 0.95) with energy expenditure during walking and running on a treadmill or with other defined activities. An increasing number of accelerometers has also been validated against DLW under unconfined conditions in daily life. The Actigraph/CSA/MTI and the Tracmor were the two most extensively validated accelerometers. The best results were found for the Tracmor, however, this accelerometer is not commercially available yet. Of those commercially available, only the Actigraph/CSA/MTI has been proven to correlate reasonably with doubly labeled water derived energy expenditure.