Wearable electronics is the coming thing, and fitness-related gear is the most obvious thing to wear. And CES had a huge section dedicated to these semi-health devices. “Semi” because it’s this nice cozy niche where you can do things that affect your health with no required FDA approval.

But the scale of integration is pretty astounding. One example was a company called Valencell that has designed sensors that fit into an earbud. Actually, it’s more than just the sensor – there’s a lot of computing that goes on in that little thing that still has to be comfortable to wear (which was a challenge for them).

First, they have an IR emitter and detector that senses heart rate. Then they have an accelerometer to estimate pace, distance, and step rate. All of this information can be used to estimate oxygen and calories burned.

The sensors interact with your phone, but they don’t rely on the phone to do all the work: there’s also a DSP in the headset that processes the sensor data. What the phone gets is the final result for display to the runner.

Some of the challenges – in addition to the simple issues of size and comfort – included:

• Resting heart rate is pretty straightforward to detect, but when running, there’s so much noise that it’s hard to reject the extraneous artifacts.
• Indoor and outdoor light profiles are very different; the system has to handle both. The sun in particular has lots of IR in its light spectrum, and that has to be rejected. They have to be able to handle running into and out of shadows.
• They can detect your stride +/- 10% if constant, or you can train it to get to +/- 5%. They can interpret transitions between walking and running.

As a “running” app with an accelerometer, it might be tempting to think of this as a navigation thing that it’s detecting, but it’s not; it’s interpreting the bumping around as you bounce with each step. It knows how many steps you took; it has no idea where those steps went.

They don’t make the end products themselves; they license the technology to audio/headset makers for integration into their systems, whether wired or wireless (e.g., Bluetooth). You can find more at their website.