Originally Posted by Chrissie-fan
Good point about the toll it might take on her body in the long run to just be a retreiver of balls.
Not really, imho. There is no empirical evidence to suggest such a claim.
Athletes with predominantly short muscle fibers will excel in sports requiring explosive contraction of muscles. Sprinters as an example. They rarely are competitive at a 'high' age. They are also very prone to injuries, as the explosive movements is a big strain on muscles and the body. Tennis BBB's fall into this category.
Athletes with predominantly long muscle fibers will excel in sports requiring stamina. The marathon runner is the example here. They are often quite competitive at an 'old' age and are normally not as injury prone as 'power' athletes. The main cause of injury stems from exhaustion. Tennis 'pushers' fall into this category.
Playing style alone, favours the tennis pusher. However, obviously other things play a big role. Genetics. Training methods. Eating habits and blah blah.