Inertial measurement units worn on the dorsum of the foot and proximal to the ankle can provide valid slip recovery measures.
Michelle A Morris, Christopher T Franck, Michael L Madigan
PMID 39514916WHAT IT FOUND
Wearable sensors on the top of the foot or just above the ankle accurately measured how far and fast an older adult's foot slid during a lab-induced slip.
They matched gold-standard camera data closely. Participants could put the foot sensors on themselves with similar accuracy to researchers.
Key findings
01IMU-based slip measures strongly correlated with motion capture measures (r >= 0.94) and differed significantly between falls and recoveries.
02Foot IMUs placed by participants still showed strong correlation with motion capture measures (r >= 0.92), despite greater variance in some metrics compared to researcher-placed units.
03Ankle IMUs generally underestimated slip measures compared to motion capture, likely due to foot movement during the slip, but remained valid alternatives.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The slip was induced in a highly controlled lab setting using oil on vinyl, which may not reflect the variety of real-world slipping surfaces or mechanisms. The sample size was small (27 analyzed slips) and derived from a prior study's resources. The oil application was not perfectly uniform, potentially introducing some inconsistency. The study only compared participant vs. researcher placement for foot IMUs, not ankle IMUs. Participants wore a safety harness, which might alter natural recovery responses compared to an unassisted slip.
Declared interests
The authors declared no conflicts of interest. The study was supported by NIH funding.
The easy way to misread this
Do not assume these sensors are validated for use in real-world, uncontrolled environments. The study only tested validity in a specific laboratory slip scenario with a safety harness, so generalizability to everyday falls is unclear.