Apple has successfully applied for a patent on a set of headphones that combine fitness tools such as a pedometer and a heart rate monitor. The tech could replace existing fitness monitors based in watches, wristbands and training shoes.

The patent filing actually dates back to 2008. suggesting it may have been something of a complex verification process at the US Patent and Trademark Ofice.

That would certainly make sense as the patent is a little vague and comes across more as an idea than a specific technological solution. The key to the patent seems to be making a monitoring device small enough that it could be worn on the head, with Apple suggesting this could be in an earbud (with or without an over-the-ear clip), in headphones, or as a separate unit that users could mount to existing earphones.

“Could” is certainly the magic word in the filing. It suggests that a placement near an ear means the gadget could be used to sense heartrate (by measuring a pulse) or even perspiration levels.

Another possibility is for the unit to house an accelerometer and/or a GPS tracker, both of which could track your distance, route and speed while walking or running, in the same way as existing gadgets such as Nike+ devices.

In all these cases, the idea is that the unit would be paired with a smartphone. Apple also suggests the unit could be set to turn head movements into phone controls, which could mean set-ups such as tilting your head to change volume or skip tracks.

This could work with either binary or analog level of control according to Apple, though it doesn’t detail how the system would distinguish between intentional and unintentional head movements, particularly when running.

Just in case you weren’t convinced Apple is chucking ideas at the wall for this one, the filing even suggests ” head bobbing can be used in a manner similar to Morse code in order to provide text input commands.”

It all sounds great, but the filing has a shocking lack of detail about exactly how the technology would work or what makes it unique. That suggests it may be a case of Apple getting the patent as a defensive measure rather than a sign that such a gadget is set for release any time soon.