Yesterday I was doing LL and my balance always stinks on those darn satanic}( lunges. I had a 35# bar on my shoulders, and was wobbling around so much I couldn't get through them. I picked up 15# dumbbells and it was much easier, I probably could have used 20#. What is the difference here? I could go heavier if I used the dumbbells, yet couldn't handle a bar at 35#? I know my center of gravity must be different. Am I getting the same results? Do I have to use the bar, or can I use the dumbbells? Help!