If I remember correctly from my days of studying my ACE manual, when you train your body to move in a new way (doing a new type of weight lift, learning a new choreography or cardio format, whatever involves motion) you build new neurological pathways that do not go away after they're built. If you stop your cardio work you will lose the benefits to the cardio / vascular / pulmonary systems, if you stop your strength training you will lose muscle mass and strength and endurance, and if you stop your flexibility training you will lose your . . . well, flexibility. But the how-to remains in your body memory.
A=Kpcl
(Actuall, "A-Jock" - obvioulsy typing skill has not burned itself into my muscle meormy yet)