Garmin files are data files that can be identified with the file extension TCX, according to FileInfo.com, an online searchable database of file extensions. TCX files transport fitness data between Garmin programs, which are supported by different Garmin GPS devices.
TCX files can be opened, viewed and edited, using the Garmin Training Center program, which can be downloaded from the product's website (See Resources.)
Right-click the "TCX" file.
Click "Open With."
Select the "Choose Default Program" option.
Select Garmin Training Center.
Click on "Browse" only if you cannot see the Garmin Training Center. Search for it, select it and click on "Open."
Click "OK." Your TCX file will open now and you will be able to view it and edit it.