So, I have been working out intensely since September and during the summer I want to trim the weight I've gained and have that ripped/chiseled effect. I lift heavy for my size (18 yrs old, 5'4, 120 lbs) and I was just making sure that when I start doing intense cardio that the muscle I've gained won't go away. I know a little will and that's inevitable, but I don't want it all to go away. The chiseled effect and the veins and abs come w/ conditioning. Since I have been on the current workout routine, I have gained muscle in arms and chest a lot. Am I suppose to still workout like normal, but with lower pound weights? How much do you decrease what you lift normally when you're trying to tone and shape? How long should this go on, if I am very consistent with it? And when do I go back to the heavy muscle building routine?

I suggest you mix in cardio with lower weights/higher reps.

If you don't want to "lose" your normal heavy set, then about 2 times a week, lift your normal heavy set. This way, you're toning down while maintaining your size.