GPX Viewer has the ability to display information that can not be usually recorded by smartphones such as cadence, heart rate, power, or temperature. To record tracks with such information data can be imported from different apps or devices. These files coming from the apps such as Strava or Garmin devices (usually providing output in .fit file type) can be converted in either websites or applications to GPX or KML files.

Convertor to GPX or KML file type: GPS Visualizer
In GPS Visualizer you can turn a wide variety of files into the GPX type (GPX XML) or KML file type (Google Earth (Keyhole) Markup Language).

Convertor from FIT, GPX, TCX, and CSV files to KML file type: GOTOES tool

Application for turning Strava files to GPX: Strava GPX