If you give an asterick to Performance Enhancing Drugs, then you ought to asterick Artificial turf runners.
Would Barry Sanders or Emit Smith be as good on grass as they were on rugs?
Artificial turf was "PERFORMANCE ENHANCING TURF".
Jim Brown would still be the all time rushing champion if artificial turf rugs wouldn't have been used.
Whats the difference between performance enhancing drugs and performance enhancing surfaces?