What happens before the first step? A New Approach to Quantifying Gait Initiation Using a Wearable Sensor

Area of Science:

• Biomechanics
• Wearable Technology
• Gerontology

Background:

• Gait initiation is a complex volitional behavior involving planning and execution.
• Laboratory studies identify three phases of gait initiation: anticipatory postural adjustment (APA) and step execution.
• Current routine gait testing outside labs primarily focuses on gait execution, excluding initiation measures.

Purpose of the Study:

• To determine if a single inertial measurement unit (IMU) sensor can effectively evaluate gait initiation outside laboratory settings.
• To assess the feasibility of using wearable sensors for gait initiation analysis in both young and older adults.

Main Methods:

• Young (N=41) and older (N=26) adults walked following an auditory cue.
• A 3D accelerometer (IMU) on the lower back and an instrumented gait mat recorded walking.
• An algorithm extracted gait initiation time, time-to-APA, APA duration, and swing time from sensor data.

Main Results:

• The wearable sensor demonstrated good to excellent agreement (mean ICC=0.88) with the gait mat for gait initiation metrics.
• Older adults exhibited longer gait initiation time, time-to-APA, and APA duration compared to young adults (p<0.01).
• Swing time did not significantly differ between age groups.

Conclusions:

• A single IMU sensor is a viable tool for assessing gait initiation outside the lab.
• This approach can enhance research into mobility impairments by including gait planning and execution measures.
• Findings suggest potential age-related differences in gait initiation processes beyond simple execution.