Is diastasis recti a common injury among athletes and if so will it eventually inhibit there performance and resistance training?

No/Unlikely: Normally, the paired rectus abdominus ("6-pack") muscles are fused together in the midline. Separation of these muscles, diastasis, is common w/premature infants & following increased abdominal girth (pregnancy, obesity). This is not typically found in athletes nor should it affect function. This should be distinguished from a hernia, which is an actual hole in the abdominal wall.

No: This is when the connection between the rectus muscles (six pack) thins and spreads out. This looks like a long bulge in the middle between the umbilicus and breast bone only when you are doing a sit up, or participating in a limbo contest. It's not dangerous, and rarely if ever causes symptoms. No compromise of function.