Accuracy in Wrist-Worn, Sensor-Based Measurements of Heart Rate and Energy Expenditure in a Diverse Cohort
Level 3 - non-randomized controlled study
Non-randomized observational validation study comparing multiple consumer devices against reference standards
OpenAlex W2618581983 · doi:10.3390/jpm7020003
What was done
Sixty volunteers (29 male, 31 female; age 38 ± 11 years) with diverse age, height, weight, skin tone, and fitness levels were evaluated using seven commercial wrist-worn devices: Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn, and Samsung Gear S2. Participants completed sitting, walking, running, and cycling protocols while device measurements of heart rate (HR) and energy expenditure (EE) were compared concurrently against continuous telemetry and indirect calorimetry.
What was found
Device error varied by activity and user characteristics: error was lowest for cycling and highest for walking, and increased among males, individuals with higher body mass index, and those with darker skin tone. Six of the seven devices achieved a median HR error under 5% during cycling. Conversely, no device achieved an error below 20% for energy expenditure. Across both metrics, the Apple Watch had the lowest overall error and the Samsung Gear S2 had the highest.
Why it matters
While consumer wearables reliably track heart rate during common laboratory activities, their energy expenditure estimates are consistently inaccurate and should not be relied upon for clinical or health improvement interventions.
Limits
The sample size was modest (n = 60) and testing was restricted to controlled, laboratory-based activities rather than free-living conditions. Specific numerical error percentages were omitted in the abstract for most individual devices, walking, and running.
Cited by
- partial Smartwatches that rely solely on photoplethysmography (PPG) are accurate for measuring heart rate at rest but are inaccurate during exercise.