Powered by Perform Tek Precision Biometrics technology, the iRiver On headphones include a light emitter and light sensor in one earpiece. The emitter shines a light through the skin of the ear and into nearby blood vessels. While much of the light is absorbed by skin, the remainder actually bounces back to the paired sensor.

The tech-magic here is that Perform Tek has calculated a method to transform that returning light into heart-rate data. And from there, the Perform Tek system, which includes an API with architecture for mixing in geography and accelerometer data from the smartphone in addition to the light sensor, gathers and displays all sorts of bio-info, including distance, speed, cadence, and aerobic performance.

We caught up with Perform Tek at CES 2013 where reps were speed-walking on a treadmill with a Perform Tek prototype firmer in ear.We could see their heartrates climb or drop as they walked-and-talked with passerby or simply strode in silence.

The iRiver On headphones, the first product to launch with PerformTek’s tech built-in, will work over Bluetooth 3.0 with an app for Android and iOS when it launches in March. We hit up the iRiver booth at CES for a sneak peak of the application as well.Things were pretty straight-forward with output channels to measure calories, distance traveled, long-term performance, and even a section to store your favorite workout mixes.

We were also stoked by the design of iRiver’s headset. Similar to Apple earpods, the all-white headphones were contoured to fit ear canals but there were a bit softer and more snug. What really excited us however was the fact the headphones extended out of a collar that’s worn around the neck. The collar was adjustable to help limit jostle as well. Another bonus: the iRiver On works for making calls too.

For fitness-fans and runners, it looks the iRiver On could be a must-have gadget, depending on how well it performs once it’s released this spring. Bet you can’t wait to get your run on, though.