Wrist-based accelerometer cut-points for quantifying moderate-to-vigorous intensity physical activity in Parkinson's disease.
Brenda Jeng, Katie L J Cederberg, Byron Lai and 3 others
PMID 34749075WHAT IT FOUND
People with Parkinson's need a wrist accelerometer cut-point of 2,883 counts per minute to flag moderate-to-vigorous activity, versus 4,389 for healthy adults.
Using the standard higher threshold undercounts their activity because their movement is less efficient.
Key findings
01The validated cut-point for moderate-to-vigorous physical activity in Parkinson's disease is 2,883 counts per minute, significantly lower than the 4,389 counts per minute required for controls.
02Individuals with Parkinson's disease exhibit a steeper relationship between wrist accelerometer counts and energy expenditure compared to healthy controls, despite similar walking speeds.
03Wrist-worn accelerometers show a strong linear association with energy expenditure in both groups, supporting their use for measuring activity intensity in Parkinson's disease.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The sample was restricted to individuals with mild-to-moderate Parkinson's disease who were in the 'on-medication' state, so these cut-points may not apply to those with severe motor impairment or upper extremity symptoms like rigidity or dyskinesia. The study used research-grade devices with proprietary software to calculate vector magnitude, which is not readily accessible or interpretable for the general population or clinical settings using consumer devices. Four participants with Parkinson's and three controls were excluded from the analysis because they used handrails during walking, which could affect the generalizability of the findings to patients who rely on assistive devices.
Declared interests
The authors declared no conflicts of interest. The study was supported by the National Institutes of Health.
The easy way to misread this
Do not apply these cut-points to consumer-grade smartwatches or patients with severe Parkinson's disease. The values were derived from research-grade ActiGraph devices in a specific mild-to-moderate population and require proprietary software to calculate vector magnitude.