Standardizing accelerometer-based activity monitor calibration and output reporting

Area of Science:

• Biomechanics
• Wearable Technology
• Physical Activity Assessment

Background:

• Wearable activity monitors (AMs) estimate energy expenditure and biomechanical forces.
• Limited standardization in AM calibration and data reporting hinders utility in free-living settings.

Purpose of the Study:

• To design an inexpensive, reproducible AM testing system.
• To develop a standardized calibration method for accelerometer-based AMs.
• To evaluate the system's utility and the calibration method's accuracy.

Main Methods:

• A centrifuge-type device applied known accelerations (0-8g) to AMs.
• Matrix algebra and least squares determined a calibration matrix for custom AMs.
• Accuracy assessed by comparing applied vs. calculated accelerations.

Main Results:

• Developed an inexpensive (< $100) AM testing system.
• Achieved AM accuracy within 4% of applied accelerations.
• Demonstrated a reproducible calibration method.

Conclusions:

• The system and calibration method can enhance AM data sharing and comparability.
• Improved accuracy of AM-based models for physiological and biomechanical estimations.
• Facilitates more reliable field-based physical activity assessments.