Accelerometers

=__**Accelerometers**__=

Accelerometers are used to measure physical activity. PALMS supports accelerometers made by ActiGraph and Philips Respironics.

__**GT1M**__ (ActiGraph)

The ActiGraph GT1M is the successor to the uniaxial ActiGraph (first known as CSA and later MTI) model 7164. The GT1M is a lightweight (27g), biaxial accelerometer that measures 1.5" x 1.44" x 0.70" and has been shown to have an acceptable correlation with gold-standard energy expenditure measures.

__**GT3X**__ (ActiGraph)

The Actigraph GT3X uses a solid-state triaxial accelerometer to measure motion data on three axes. The GT3X has the same dimensions as the GT1M (27g; 1.5" x 1.44" x 0.70") and features 4MB of non-volatile flash memory. In addition, the GT3X has an extended battery life that allows for up to 20 consecutive days of data collection. The GT3X records accelerations ranging from 0.5 - 2.5 G's and the output is digitized at a rate of 30x per second (30 Hertz). The GT3X can be initialized to collect data in either GT3X or GT1M modes.

__**GT3X**__+ (ActiGraph)

The Actigraph GT3X uses a solid-state triaxial accelerometer to measure motion data on three axes. Unlike previous ActiGraph devices, the GT3X+ collects data in raw format at a user specified sample rate up to 100 Hertz. The water resistant GT3X+ can withstand submersion at depths to 1 meter for up to 30 minutes. The GT3X+ can store over 40 days of raw data, and its rechargeable battery is capable of providing power for 30 days between charges.

Details from ActiGraph

__**ActiCal**__ (Philips Respironics)

Actical Physical Activity Monitors provide an objective, quantifiable measure of Physical Activity and Energy (Caloric) Expenditure. Activity level thresholds (cut point) determination and quantitative activity analysis are recognized as being important components of weight management and sports medicine research. They can be a valuable measurement tool in any area where exercise plays a critical role.

Details from Respironics