Heart Rate Accuracy of In-ear Earbuds Validated by China National Level Athletes

Hera Leto Earbuds

In a recent study published in Scientific Reports, the Hera Leto Earbuds (Powered by WBD101 PPG Sensing Technology) was tested by 28 China national first-level athletes, including twelve females and sixteen males specializing in track and field and skiing disciplines. The study identified that Hera Leto demonstrated overall better validity during HIIT compared to Polar Verity Sense and Polar Vantage V.

The Science Behind the Validation

The study involved 28 elite athletes and compared HR data collected by Hera Leto against the gold-standard Polar H10 chest strap. The results speak for themselves:

✅ High correlation (r = 0.970, p < 0.001) with the reference device

✅ Minimal systematic bias (-0.67 bpm) and a mean absolute error of only 2 bpm 

✅ Superior performance metrics compared to leading wrist and arm-worn monitors

The Study by Researchers from the Beijing Sport University shows that Ear-based PPG devices, such as Hera Leto, hold potential as a solution to improve HR measurement validity during HIIT. This is because ear-based PPG devices typically employ multi-channel monitoring, which enhances the signal-to-noise ratio and coverage of PPG.

Moreover, during severe stress conditions, the body maximizes blood flow to maintain adequate cerebral perfusion, and in-ear PPG devices, being situated near the highly sensitive brain, can measure HR with minimal delay. Although PPG is susceptible to constriction of peripheral blood flow in low temperatures, in-ear PPG has demonstrated resistance to these effects due to the unique characteristics of the ear canal.

👉 Read the full scientific study here: https://doi.org/10.1038/s41598-025-00559-5