A networked digitally readable medium adapted to enable participants to compete virtually in a sporting activity, wherein each participant uses a system comprising a participant activity monitoring unit for monitoring a performance of the sporting activity, an activity information module for storing performance information corresponding to the sporting activity and a participant performance correlator for delivering comparative performance data based on the monitored performance of the sporting activity by each participant and the stored performance information, and wherein the participant activity monitoring unit is adapted to store the geographic position of system while the sporting activity is being performed, which networked digitally readable medium comprises computer-executable instructions that, when executed, perform the steps of: (a) storing in the networked digitally readable medium a course map and information relating to that course map; (b) making the course map and information relating to that course map available to download: characterised in that said networked digitally readable medium comprises further computer-executable instructions that, when executed, perform the steps of: (c) providing to the participant a download data key for attachment to a course run file, the course run file comprising a time stamped data run of GPS encoded data indicating the geographic position of the system while the sporting activity is being performed, and where the download data key is (i) activated for one time use by the participant who downloaded the download data key and (ii) for association with said time stamped data run, the participant activating the download data key prior to the run and ending the run directly after completion of the sporting activity over the course thereby certifying the GPS encoded data as encryption key stamped GPS encoded data in an upload race key; (d) receiving from said system at least a portion of said performance information corresponding to a performance of the sporting activity together with the upload race key, whereby the stored performance information is available for use by the participant of the sporting activity; (e) checking the upload race key for said encryption key stamped GPS encoded data representing the geographic position of the participant activity monitoring unit during performance of the sporting activity, and certifying the upload race key as a certified race result if that data is identified; (f) comparing said encryption key stamped GPS encoded data of the certified race result to ensure that the participant traversed substantially the same course as defined by the course map. (a) storing in the networked digitally readable medium a course map and information relating to that course map; (b) making the course map and information relating to that course map available to download: characterised in that said networked digitally readable medium comprises further computer-executable instructions that, when executed, perform the steps of: (c) providing to the participant a download data key for attachment to a course run file, the course run file comprising a time stamped data run of GPS encoded data indicating the geographic position of the system while the sporting activity is being performed, and where the download data key is (i) activated for one time use by the participant who downloaded the download data key and (ii) for association with said time stamped data run, the participant activating the download data key prior to the run and ending the run directly after completion of the sporting activity over the course thereby certifying the GPS encoded data as encryption key stamped GPS encoded data in an upload race key; (d) receiving from said system at least a portion of said performance information corresponding to a performance of the sporting activity together with the upload race key, whereby the stored performance information is available for use by the participant of the sporting activity; (e) checking the upload race key for said encryption key stamped GPS encoded data representing the geographic position of the participant activity monitoring unit during performance of the sporting activity, and certifying the upload race key as a certified race result if that data is identified; (f) comparing said encryption key stamped GPS encoded data of the certified race result to ensure that the participant traversed substantially the same course as defined by the course map.