Variables influencing wearable sensor outcome estimates in individuals with stroke and incomplete spinal cord injury: a pilot investigation validating two research grade sensors.
Chandrasekaran Jayaraman, Chaithanya Krishna Mummidisetty, Alannah Mannix-Slobig and 2 others
PMID 29534737WHAT IT FOUND
Wearable step counts were accurate in healthy adults but often undercounted in stroke and incomplete spinal cord injury.
Energy expenditure estimates were often inaccurate, so sensor choice and placement matter before using these numbers clinically.
Key findings
01For lying, sitting and standing, ActiGraph energy expenditure estimates were lower than the breath-by-breath reference in healthy adults, people with incomplete spinal cord injury and people with stroke.
02During a 50-step walk, healthy adults' step counts were close to the manual count, but step counts for people with stroke and incomplete spinal cord injury were often underestimated.
03No single sensor or body location was consistently accurate across step counts, energy expenditure and metabolic equivalents; accuracy changed with activity type and patient group.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was a pilot with a small number of participants, so it cannot show how these sensors perform in wider clinical populations. It tested a limited set of research-grade sensors and their manufacturer algorithms, not the many devices patients may use. All activities were done in a laboratory, not in free living, so results may not reflect everyday movement. Sedentary activities were recorded only in brief bouts, so longer or shorter real-life patterns were not tested. Participants could ambulate with or without an assistive device, so findings do not apply to people who cannot walk. The study did not measure sweat rate or skin temperature, and the authors could not inspect the Metria-IH1 fusion algorithm, so explanations for some results remain speculative. The analysis did not directly compare groups with each other or devices with each other; each sensor was compared with its reference.
Declared interests
The work was funded by the Max Näder Lab for Rehabilitation Technologies and Outcomes Research at Shirley Ryan Abilitylab. The supplied text does not give an author conflict of interest declaration.
The easy way to misread this
Do not conclude that these wearable sensors can reliably measure energy use or activity in stroke and incomplete spinal cord injury. This was a small lab pilot, and the built-in algorithms were based on healthy data; accuracy changed with sensor, location, activity and patient group.