>In the marathon you must have muscles and connective tissue strong enough to handle the pounding. Larger > muscles and connective tissue will be stronger.
Makes sense - and ultrarunners are bigger still, although the sample size for ultrarunners is so small that I don't think we can make many conclusions about optimum body types from the existing runners. > You also use more fat as fuel during a marathon than any other event. So in the marathon you'd likely > have larger mass due to more muscle and fat stores but probably due more to more muscle than fat. Even at a very low body fat >you'd have enough to go a long way. A 1% increase in body fat of a 130 lb runner would be 1.3lbs of > fat, or about 4700 calories. So you wouldn't have a large difference in % body fat between marathoners and other distance runners. You wouldn't have any real difference there since there is far more fat in the scrawniest runner than needed to do a marathon. - Ed Parrot
