If its while running, then run faster and open up ur stride, even if it means to run fo a min or 2 and have to pause to a walk to catch ur breath. Slower running / jogging will bring hell to ur calves chin splints and knees. Also look up an excercise called "the motivator"http://www.youtube.com/watch?v=kITKK5rf9kU&feature=youtube_gdata_player we do this in the army and it will get ur calves in Shape in no time