A comparison of two optical heart rate monitors over 23m of running

sports-tech 9 Oct 2015

I ran yesterday wearing two HRMs, both optical. On my right wrist, I wore a Mio Link, and in my ears, a Jabra Pulse. (Both histograms click through to interactive data.)

The data from the Link was recorded to my Suunto Ambit3 Peak, and the Pulse was recorded to their app on my iPhone. The run was over relatively even grass, and the air was 15 degrees C.

Analysis

There is the obvious discrepancy in the data at the beginning of the histogram, which is almost certainly caused by me. Whilst I had both HRMs on when I started my run, I forgot to press start on the Jabra Pulse. Whilst both had found my heart rate before I started, I suspect the Pulse operates in a low-power mode until you press start, and that pressing start whilst mid-activity makes it harder to accurately acquire a pulse.

Once we clear the calibration area (13:57:02 onwards), we can see that the %D drops to 0.69%, with a few spikes. I attribute one of these spikes to pressing the button on the Pulse for extra audio feedback, which will have moved the HRM over the skin it’s watching and introduced error.

Conclusion

The security of the Link on my wrist gives it the appearance of more stable data, as it is free from my interference (no mid-run button pressing), but given the vagaries of biometric tracking, and especially while running, a %D of 0.69% is acceptable.

Further testing

  1. Pressing start on all units before starting.
  2. Wearing a chest strap HRM at the same time as the other two, to provide a ‘classic’ benchmark.

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