Nonsense.
Serena would be healthier if she was lighter since the day she played tennis. If you think Serena’s weight and physic is an ideal type then you are simply delusional. I suggest you should go visit a doctor(if you ever had) to learn more about good health and fitness, otherwise don’t spew your ignorant in here.
Serena has muscle but she also has a lot of fat, there’s no denying that. More wear and tear on the body when carrying extra weight is not good for the knees. Duh !
An excellent example of a very fit person is Chris.
Serena’s fitness can’t compared to her pinky! Chris had played a ton of tennis, and was very consistent including making 33 slam finals in her career. Also she has great stamina/endurance, which is no surprise how dominant she was on clay. Serena fitness was poor is a testament of her weakness on clay. You can’t expect to have good stamina/endurance with so much weight.