In terms of objective measures, uniaxial (single plane) accelerometers have been widely used for epidemiologic validation studies due to their size, ease of use, and durability.
Positioning over the hip allows the assessment of vertical acceleration associated with locomotion.
This photo shows a Manufacturing Technology Inc. (MTI) accelerometer (www.mtifwb.com). For adults, the typical sampling interval is 1 minute with
minute-by-minute samples stored in the internal memory; using this interval, 22 consecutive days of data can be collected before downloading.
Other available activity monitors include the triaxial RT3 accelerometer (www.stayhealthy.com) and the Sensewear Pro Armband which includes a 2 axis
accelerometer, and sensors to measure heat flux, skin temperature and near-body ambient temperature (www.bodymedia.com).