Here is some tips to keep your historical training database to get better performance;
1). Backup the database from C:\Program Files\GlobalSat
Technology\GS-Sport Training Gym\MySQL\data before you un-installing the GS-Sport Training Gym.
(2). After new GS-Sport Training Gym uninstall/ installing accomplished, try to input "net stop mysql1" (Ver 1.8 or above no need to input)at COMMAND MODE to stop SQL services.
(3). Copy and overwrite the database back to the corresponding folder.
About more information, I posted on child board of GH-615, you may see them.
BTW, I remember your a super runner, if possible, could you post your idea about distance or speed calculation again, so that we can discuss then improve.