A second potential endurance enhancement is fake blood. Doctors and hospitals have long hunted for a safe blood substitute. Donated blood is dangerous (HIV, hepatitis, etc.), and it's difficult to collect. A product that could safely tote oxygen like hemoglobin would make surgery and emergency medicine much easier. It could also supply athletes with a safe, covert way to hike endurance.
There are two promising leads. Drug companies are spending millions to make artificial or modified hemoglobin. These manufactured substances haven't been perfected yet—the molecules tend to degrade quickly, and they may have their own health risks—but they soon will be.
A more radical idea is exploiting compounds called perfluorochemicals, which are related to Teflon. PFCs can absorb enormous amounts of oxygen—50 times as much as normal blood, in some cases. Several companies are testing PFC-emulsion blood substitutes. Rumors circulated about PFC use at the 1998 Nagano Olympics, according to Wadler. Long-distance cyclists have also been accused of doping themselves with PFCs.
Artificial hemoglobins have been cranky in tests but remain promising. There is worry about the side effects of PFCs, which can cause platelet dysfunction and flulike symptoms, according to Wadler.
The Timeline: Both manufactured hemoglobin and PFCs are likely to be used widely in a few years, assuming clinical trials go well.