When New York regulators hastily issued a directive Tuesday that prohibits a horse from racing within seven days of spending time in a hyperbaric oxygen chamber, the New York State Racing and Wagering Board appeared to be getting out in front of a potential problem by making it illegal to use the chamber for performance-enhancing purposes.\nNew York was the first state to issue a specific rule on the use of hyperbaric oxygen chambers, though two Florida tracks - Gulfstream Park and Calder Race Course - adopted house rules earlier this year restricting their use to no closer than 72 hours prior to a race. The policies appear to have good intentions - if someone told a horseplayer, horse owner, or trainer that a horse had received pure oxygen within 24 hours of winning a race, very few people would blame that person for contending that the horse had an advantage.\nThe only problem with that opinion is that it's wrong, according to most veterinarians and a review of the available science.\n"The only way it could possibly be performance-enhancing is if you led them out of the chamber directly into the starting gate," said Foster Northrup, a Kentucky-based veterinarian who has studied the use of hyperbaric oxygen for the Kentucky Horse Racing Commission and the American Association of Equine Practitioners's Racing Task Force. "We all know that's impossible. And even if you did that, I don't know if it would be performance-enhancing. Pure oxygen can make you feel a little weird."\nHyperbaric oxygen chambers are airtight containers in which horses receive doses of pure oxygen (atmospheric air is approximately 21 percent oxygen). The higher concentration results in a larger concentration of oxygen in the blood. The chambers are the reverse of altitude chambers, in which the air is starved of oxygen to mimic conditions at higher altitudes.\nDespite the fact that no scientific evidence associates hyperbaric oxygen with performance enhancement, regulators will probably push forward in other states to restrict the practice. The reason is simple: Most horseplayers and trainers will simply maintain that the science is incomplete or wrong, so racing ends up with regulations banning a practice that doesn't do anything at all, and, perversely, validates the opinion that it enhances performance. Why else would it be illegal?\nIt's not that uncommon for racing to adopt a zero-tolerance policy on drugs or treatments that do not influence performance. Take the well-publicized case of Steve Asmussen in Texas. The trainer was recently issued a six-month suspension by the Texas Racing Commission for the finding of a minute quantity of lidocaine in a post-race test, despite the fact that the concentration of the drug indicated that it could not have possibly influenced how the horse performed. Asmussen has appealed to the civil courts.\nHyperbaric oxygen treatments are not necessarily new in racing, but the treatments - which can cost from $250 to $400 per session - have steadily gained in popularity over the past several years. Nearly all scientists and veterinarians agree that the treatments can be beneficial, especially for horses who have suffered injuries or infections. By increasing the concentration of oxygen in a horse's bloodstream, the body is better able to repair tissues and fight viruses, according to scientific literature. But those benefits almost instantly disappear after the horse exits the chamber.\nHowever, like all treatments or therapies that are new and expensive, the claims have steadily outgrown the facts. And though no one is openly advertising that the treatments can enhance performance, the subtext is out there.\nIn fact, Gulfstream passed its house rule this year restricting the treatments after the owner of a mobile hyperbaric chamber was accused of allowing horses to use the chamber on raceday. The complaints came from trainers who weren't using the chamber and who feared that the competition was getting a leg up, according to racing officials.\n"This is the racing industry, and there's a lot of superstition out there," said Dr. Mary Scollay, the equine medical director of the Kentucky Horse Racing Commission. "It's the blue sock theory. If a trainer wears one blue sock one day and he gets a winner, everyone shows up wearing a blue sock the next day."\nScollay is one of a number of racing officials who believe that the racing industry is better off tackling errors in public perception rather than passing rules against blue socks, even if it means conspiracy theorists will have a wider platform.\n"At some point, you have to go head-to-head with public perception and say, 'Hey, you guys got this one wrong,' " Scollay said. "Then it's up to us to create a compelling message to convince people that the science is right."