Metabolic Holter Assessment

Metabolic Holter Assessment

Metabolic holter(armband), a comfortable, clinically-validated device that is worn on the back of the upper arm. The armband continuously records an array of physiological data. The collected data is then analyzed and organized into graphs and reports that clearly display your energy expenditure (calories burned), duration and level of physical activity, number of steps taken, and sleep/wake states. The slim design of the Armband minimizes interference with the day-to-day activity. It can be discreetly worn under clothing and, unlike other types of single-sensor monitors, you can comfortably wear the monitor while sleeping, exercising or simply going about their daily routine.


The wGT3X-BT based wireless activity monitors provide objective measurements of human activity and are used in many research and clinical applications. They include both a micro-electro-mechanical system (MEMS) based accelerometer and an ambient light sensor.

Acceleration: The acceleration data is sampled by a 12 bit analog to digital converter at rates ranging from 30 Hz to 100 Hz (user selectable) and stored in a raw, non-filtered/accumulated format in the units of gravity (G’s). This data is stored directly into non-volatile flash memory.

Ambient Light: Ambient light data is sampled and stored to memory at a 1 Hz rate. When a downloaded data file is converted into an accumulated *.agd format with epoch lengths greater than one second, the lux values for that epoch are averaged.

Post Processed Data: The collected activity data can be utilized in a post-processed environment (ActiLife 6) to determine steps per epoch as well as inclinometer information.

Steps: Step counts are accumulated on a per-epoch basis and are based on accelerometer data collected on the vertical axis. An algorithm present in the device firmware filters out the accelerometer’s baseline noise level to help accurately accumulate the steps-per-epoch.

Inclinometer: The post-processed inclinometer feature helps users identify the orientation of the device and, more importantly, when the device itself was taken off. Each epoch is flagged with a number (1 through 4) to indicate the orientation of the device during that epoch. More details are available in the Inclinometer Whitepaper

Low Frequency Extension: The Low Frequency Extension (LFE) option, though not a mode or channel, is another data collection option during post-processing for the GT3X+ and

wGT3X+. The standard proprietary filter algorithm used in ActiGraph products is used to eliminate any acceleration noise outside of the normal human activity frequency bandwidth. This filter is customized to work with ActiGraph’s Energy Expenditure Algorithms. The LFE option, when enabled, increases sensitivity to very low amplitude activities allowing for the study of population groups who move slowly or take very light steps (for example, the elderly). For more details, contact ActiGraph at

Data Collection

Initialize time options/selections have been reduced significantly due to the new data collection method used by the GT3X+ and beyond devices. During initialization, the user is now only required to select the desired raw data sample frequency (30Hz up to 100Hz in 10Hz increments). Data is automatically collected from all on-board sensors in raw data format. The data recorded includes:

  • Vertical Axis Activity Acceleration Data (Axis 1)
  • Horizontal Axis Activity Acceleration Data (Axis 2)
  • Perpendicular Axis Activity Acceleration Data (Axis 3)
  • Ambient Light (Lux)

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