I don't think a simple measurement with a tape measure can justify that the actual rib structure has changed. Pullovers can stimulate the serratus to grow which would be included in such a measurement, and any growth in the latissimus Dorsi would also be represented in measuring below the pectorials.Originally posted by ExtremeAnabolic
Well...there are two schools of thought on this subject. The old school claims the cartilage connecting the rib cage itself and to the sternum is made of a slightly different kind of cartilage. It is apparently more pliable (especially when you are young) and can be stretched somewhat. The newer school says the expansion is caused by the tissue (muscle tissue) in the area of the rib cage. I adhere to this newer theory. When I was younger I did heavy pullovers preceeded by breathing squats and eventually ended up with a three inch gain in the area of the rib cage. I measured under the pectorals so as not to throw off the measurement due to any size gain in the pecs.
At any rate, pullovers arn't a useless exercise, especially if they're done with a pullover machine.