Accuracy of wrist-worn heart rate monitors during physical therapy sessions among hemiparetic inpatients with stroke.
Masaki Kobayashi, Tomoyuki Shinohara, Shigeru Usuda
PMID 33519074WHAT IT FOUND
Wrist heart-rate monitors on hemiparetic stroke inpatients tracked chest readings on average, but individual readings could be far off during physical therapy.
They may be useful for rough monitoring, not precise intensity control.
Key findings
01During therapy, wrist readings averaged 1.0 beats/min higher than chest readings on the non-paretic wrist and 0.4 beats/min higher on the paretic wrist.
02The average wrist-versus-chest error was 6.7% on the non-paretic wrist and 5.9% on the paretic wrist, but the limits of agreement showed single-reading differences from -21.8 to 23.8 beats/min non-paretic and -20.8 to 21.6 beats/min paretic.
03Wrist and chest readings were substantially related, with intraclass correlation coefficients of 0.75 on the non-paretic wrist and 0.79 on the paretic wrist by the study's own thresholds.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 30 participants were analysed, and sample size was not calculated, so the study is small for judging device accuracy. Only the Polar A370 wrist monitor model was tested, so results may not apply to other watches. The chest and wrist devices were not perfectly time-synchronised, so some difference may reflect timing rather than monitor error. Only two patients with atrial fibrillation were included, and their effect on readings was not clear. Participants were subacute inpatients able to do physical therapy, so findings may not apply to more severe or less mobile patients.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that wrist monitors are accurate enough for precise exercise intensity because the average difference was small. The limits of agreement showed single readings could differ from the chest reading by 23.8 beats/min above or 21.8 beats/min below on the non-paretic side, and by 21.6 beats/min above or 20.8 beats/min below on the paretic side.