My wife has been using this earplug "thingy" for a while now.
It's clearly at the early stages (just out recently from a Kickstarter campaign), but still, it's fairly effective in tracking any kind of indoor sport activity - although the sensors seem to be calibrated more for high performers rather than amateur users.
The app has quite a bit of potential and, if the team nails it on delivering a great companion app and possibly API driven integration with some of the biggest health and fitness player out there, they may go a long way.
PS: (I didn't fill in the "maker" yet as @lumafit is the only Twitter handle I could find from their team - I asked the founder to provide me his own so that I can then update this hunt)
handshakes.work