GPSBabel program supports both the TRK and GPX format so it is your best bet to perform this conversion.
Convert CompeGPS Land track file to GPS eXchange format.
We found 3 software records in the database related to .trk to .gpx file format conversion.
Microsoft Windows software - convert trk to gpx on Windows
A program for conversion of various waypoint and GPS map formats
Convert from trk file format
|Yes, GPSBabel supports trk file conversion as a source file type.||No||No||No||No||No||No||No|
|Yes, GPSBabel supports gpx file conversion as a target file type.||No||No||No||No||No||No||No|
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned trk to gpx. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert trk to gpx on OS X
Application that allows users to convert waypoints and GPS map formats.
Linux/Unix software - convert trk to gpx on Linux
Program for Linux that allows users to covnert waypoints, tracks, and routes between popular GPS receivers.