Previously if you used GK training on a non-goalkeeper, the player would lose condition but would retain some 'hidden' training boost that would be released when you next trained them with a normal training drill.
Goalkeeper Training only trains Goalkeeper white skills:
Attachment 100671Attachment 100673
With the new update, if you include Goalkeeper Training in a set of drills, and non-GK players are trained with that set of drills, then the non-GK players will still lose 3% Condition for the Goalkeeper Training drill but will not gain the 'hidden' training boost.