The long article about his punishing workout schedule says growth hormone to me. It's stupid to check just before a race. Dopers don't use amphetamines for one race. It's the drugs that allow your body to heal after many giant workouts that make a champion cheater. There is always good reason to support the runners who have persisted for years and suspect the ones who vault to the top suddenly. The real champs have many world class times before they shave the WR.