Today I skipped my Leg workout and just used my Elliptical, I did two sessions of Elliptical for a total of 20 minute or 400 calories burned. I really don't have any problem building leg muscle and even just doing the Elliptical as my regular warmup exercises is probably enough for me to keep my legs toned... Next week I'll start back up with legs, it's been a good idea to lay off for a while and let my back get back to normal.