Validation of photoplethysmography as a method to detect heart rate during rest and exercise

TLDR

Wearable photoplethysmographic heart rate monitors lack validated accuracy despite widespread use. The study tested 47 healthy adults performing seven 6‑minute exercise bouts while wearing Omron HR500U and Mio Alpha devices, with data compared to a Polar RS800CX reference and error computed over minutes 2–5. Mio Alpha showed significant discrepancies from the Polar reference during walking, biking, and weight‑lifting, while Omron HR500U differed during walking and weight‑lifting; additionally, Mio Alpha errors correlated with jogging speed and varied with skin phototype.

Abstract

Despite their enhanced marketplace visibility, validity of wearable photoplethysmographic heart rate monitoring is scarce. Forty-seven healthy participants performed seven, 6-min exercise bouts and completed a valid skin type scale. Participants wore an Omron HR500U (OHR) and a Mio Alpha (MA), two commercial wearable photoplethysmographic heart rate monitors. Data were compared to a Polar RS800CX (PRS). Means and error were calculated between devices using minutes 2–5. Compared to PRS, MA data was significantly different in walking, biking (2.41 ± 3.99 bpm and 3.26 ± 11.38 bpm, p < 0.05) and weight lifting (23.30 ± 31.94 bpm, p < 0.01). OHR differed from PRS in walking (4.95 ± 7.53 bpm, p < 0.05) and weight lifting (4.67 ± 8.95 bpm, p < 0.05). MA during elliptical, stair climbing and biking conditions demonstrated a strong correlation between jogging speed and error (r = 0.55, p < 0.0001), and showed differences in participants with less photosensitive skin.