rotation of the legs/ feet will not have a effect on calf development.. since the calves do not attach into the hips which are responsible for the foot rotation, it is pointless.. that being said, all that is needed is to change how you roll up onto your feet.. this is what xcel is feeling..keep the load over the big toe versus over the pinky toe.. people got the idea that they can effect the stress of the calf by pointing the feet one way or another because one would naturally roll over the big toe or the pinky toe with the load because of the position of the body.. the same effect can happen by putting your feet straight but, just rolling onto the big or little toe.. much safer on the hips.. all that aside.. i belive that if you put the feet forward and roll up evenly you will get complete development.. just pile on the weight..