Stride length determination during overground running using a single foot-mounted inertial measurement unit

Area of Science:

• Biomechanics
• Sports Science
• Wearable Technology

Background:

• Stride length (SL) is vital for understanding locomotion speed and running gait control.
• Estimating SL using body-mounted inertial measurement units (IMUs) shows promise, but often requires multiple sensors or focuses on walking.

Purpose of the Study:

• To assess the concurrent validity of a single, foot-mounted 9-degree of freedom IMU for estimating running stride length (SL).
• To evaluate the accuracy of a running-specific Kalman filter based zero-velocity update (ZUPT) algorithm for SL vector calculation.

Main Methods:

• A single, foot-mounted 9-degree of freedom IMU was used to estimate SL vectors during running.
• A running-specific Kalman filter based ZUPT algorithm was employed for stride detection and SL calculation.
• IMU-derived SLs were compared against a 6-camera 3D motion capture system.

Main Results:

• The analytical procedures successfully identified all strides captured by the motion capture system.
• Excellent absolute agreement was found between the IMU method and the 3D motion capture system (ICC(3,1) = 0.955).

Conclusions:

• A single, foot-mounted IMU can accurately estimate individual stride length vectors during running.
• This validates the use of wearable IMUs for precise gait analysis in controlled laboratory settings.