Gait event detection using a thigh-worn accelerometer.
Reed D Gurchiek, Cole P Garabed, Ryan S McGinnis
PMID 32535399WHAT IT FOUND
A thigh-worn accelerometer estimates gait events with small errors, averaging 39 ms for foot contact and 28 ms for foot off.
For biomechanical analyses, assume stance begins 91 ms after estimated foot contact and swing ends 70 ms before estimated foot off to maintain 95% confidence.
Key findings
01The mean absolute error for estimating foot contact events was 39 ms and for foot off events was 28 ms across 3,898 strides.
02To apply stance-phase assumptions with 95% confidence, data must be taken at least 51 ms after the estimated foot contact event; for swing-phase assumptions, data must be taken at least 70 ms before the estimated foot off event.
03Spatiotemporal variables like stride, stance, and swing times showed strong correlations with ground truth (r ≥ 0.80) and low absolute errors (11 to 46 ms).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study tested only healthy young adults (21 ± 3 years old). It did not include patients with neurological or musculoskeletal conditions, so error margins may differ in clinical populations. Walking occurred on a treadmill, which may not fully replicate overground gait variability. The study focused on algorithmic accuracy, not clinical outcomes or patient management strategies.
Declared interests
One author owns stock in MC10, Inc., a conflict managed by the University of Vermont.
The easy way to misread this
Do not interpret the small average errors as meaning the event timing is exact for every step. The 95% limits of agreement show that estimated foot contact can be off by up to 91 ms in either direction, so strict adherence to the recommended time margins is necessary for accurate phase-dependent analysis.