How would it determine that? A GPS is often the answer but only works in open spaces and then is power hungry. My bet is speed would be done in a smart phone and your HRM would be in the wrist device.
I didn't google this area but as it's an area I know about (GPS tracking, speed) I added this reply.
I am looking for Wearable Medical or Fitness Trackers that have an open API (paid or free) that contains Time Series Data on Speed and Heart Rate.