Validity of Hera Leto consumer earbuds for heart rate monitoring during stationary cycling

Heart rate (HR) monitoring using earbuds presents a promising avenue for precise measurement, yet its validity remains under investigation during stationary cycling. In this study, we assessed the validity of the Hera Leto consumer earbuds by enrolling twenty-eight athletes as participants. Each participant wore a chest-strap Polar H10, considered the gold-standard reference, while simultaneously testing three HR monitors: the Hera Leto (worn on the ears), the Polar Verity Sense (worn on the upper arm), and the Polar Vantage V (worn on the wrist). The exercise protocol included four steady-state exercise sessions, six sessions of severe intensity exhaustive exercise, and three high-intensity interval training (HIIT) sessions. Our findings revealed a robust correlation ([Formula: see text]=0.970, [Formula: see text]<0.001) between the HR measurements obtained from Hera Leto and Polar H10 across all exercise intensities, with a minimal systematic bias of - 0.67 bpm. with a minimal systematic bias of -0.67 bpm. Notably, Hera Leto demonstrated superior performance, with a mean absolute error (MAE) of 2 bpm and concordance correlation coefficient (CCC) of 0.97, compared to the Polar Verity Sense (MAE = 4 bpm, CCC = 0.88) and Polar Vantage V (MAE = 4 bpm, CCC = 0.93). Although the precision of HR measurement decreased with increasing exercise intensity, Hera Leto exhibited a slower onset of this decline compared to the other devices. Overall, our study underscores the potential of Hera Leto earbuds as a valid tool for HR monitoring, particularly in scenarios involving steady-state exercise.