If you try downloading these files but they are saved as htm files do the following:
(Instructions apply to Internet Explorer)
Right click the link and select "Save Target As..."
Change the extension of the filename from ".htm" to ".gpx" (for gpx files) or ".trl" (for Tracklogs files).
If you have already downloaded files as .htm files you can also simply change the extension on the downloaded file and it will work.