Details on Zephyr Bioharness 3 ($429) or Zephyr Bioharness ZL ($199) HRMs

I am very interested in the Zephyr Bioharness 3 ($429) and just released Zephyr Bioharness ZL ($199).

Details on both of these devices are severely lacking on the Zephyr website and email support hasn’t been very helpful. What I was able to find out, is the hardware is the same for both, but the Bioharness ZL has different firmware. I assume that it limits the data you can get out of the ZL device compared to the 3 and it appears there is a $99 subscription required to use the ZL.

There are currently 3 android apps you can use with both? devices, but it isn’t clear if you can get historical data out of any of them (ZephyrMD looks most promising.) It also isn’t clear if the $99 subscription to use the ZL device with the android apps or just the website

Has anyone used either device or have any additional info they can share?

I’m also looking for a good solution for continuous heart rate monitoring. It seems that a lot of the devices available don’t let your data out of their system and require subscriptions, which is pretty awful.

The Zephyr stuff claims to track a lot of different variables, but does not seem to say how they do it. How do they work out posture from a chest strap?


They use an accelerometer for posture. Because the accelerometer detects the force and direction of gravity relative to the device it’s pretty straight forward to calculate it’s orientation. If that device is attached to your chest you know the orientation of your chest or your posture.

I have a bioharness 3 and it is assume. There is one app that collects your historical data which also makes automated calculations (like BMI and caloric output thresholds, etc), then takes your excercise data and compares it to other types of athletes’ average stats. One was a tour de france bicyclist which my stats were horrible incomparison with. Also, the app makes suggestions as to type and frequency of workout will best suit your goals.