Files with the .TCX contain fitness data encoded in the XML format and used for exchanging information between Garmin devices. The data can contain information such as the type of the undertaken sport, the measured times, the travelled distance, the burnt calories, and the intensity of the training.

TCX files in both of their forms can be opened using special software developed by Garmin called Training Center. The format is also supported by MotionBased.Com and the Garmin Communicator Plugin.