Repeatability of Inertial Measurements of Spinal Posture in Daily Life

Area of Science:

• Biomechanics
• Wearable technology
• Health monitoring

Background:

• Posture, physical activity, and sleep are crucial health indicators but challenging to measure long-term.
• Inertial measurement units (IMUs) offer potential for longitudinal monitoring of these behaviors.
• Characterizing IMU measurement repeatability in real-world settings is essential.

Purpose of the Study:

• To assess the repeatability of IMU-based spine posture and movement measurements.
• To compare lab-based versus home-based standardized tasks for IMU measurements.
• To identify factors affecting data quality for real-world IMU applications.

Main Methods:

• Utilized IMUs to measure spine posture and movement during standardized tasks.
• Compared repeatability of measurements performed in a lab versus at home.
• Evaluated five methods for estimating reference spine posture.
• Assessed data quality issues, including magnetic interference, over 2-day periods.

Main Results:

• Moderate repeatability was found for spinal motion range (ICC = 0.67).
• Absolute spine angles were more variable; reference posture estimation was critical.
• A composite set of standardized tasks yielded the best reference posture estimation (ICC = 0.72 ± 0.17).
• Magnetic interference significantly impacted data quality in 43% of analyzed daily life data.

Conclusions:

• IMUs show promise for assessing spinal motion but require robust methods for reference posture.
• Standardized task protocols can enhance measurement repeatability.
• Further research and sensor cross-validation are needed to optimize IMU methodology for health monitoring.
• Strategies to mitigate magnetic interference are crucial for reliable long-term data collection.