IMU positioning affects range of motion measurement during squat motion analysis

Area of Science:

• Biomechanics and Sports Science
• Rehabilitation Engineering
• Wearable Sensor Technology

Background:

• Inertial Measurement Units (IMUs) offer accessible motion analysis for sports and clinical use.
• IMU accuracy is often compromised by sensor errors, necessitating complex calibration.
• Simplified motion assessment protocols are needed for pragmatic clinical applications.

Purpose of the Study:

• To evaluate the impact of thigh sensor positioning on Inertial Measurement Unit (IMU) accuracy for squat range of motion (ROM) assessment.
• To determine if IMU-based squat ROM analysis is feasible without prior sensor calibration.
• To identify optimal IMU placement on the thigh for reliable kinematic data.

Main Methods:

• Three IMUs were attached along the thigh to record kinematics during squat motion.
• Data was compared against an optoelectronic reference system for validation.
• Analysis focused on range of motion, squat count, and timing without calibration.

Main Results:

• The IMU system demonstrated high concordance (coefficients > 0.944) with the reference system, even without calibration.
• Sensor placement on the distal thigh segment showed a preference for kinematic data accuracy.
• Reliable squat kinematics and timing were achieved with specific IMU placements.

Conclusions:

• IMUs can provide accurate, calibration-free squat range of motion assessment in a clinical setting.
• Strategic sensor positioning on the thigh is crucial for maximizing IMU accuracy.
• This approach simplifies motion analysis, enhancing accessibility for rehabilitation and sports applications.