Working with sports giant Nike in Oregon, the trio ran on treadmills in a greenhouse-like chamber in which temperature and humidity can be turned up as far as desired.
To heighten the sauna-like effect, they've also been running in waterproof rainsuits.
"We're having to really watch our hydration," Yoder Begley said.
Bob Williams is a one-time Olympic-trials competitor who is now a coach in Portland, Oregon. Acclimatization, he said, takes about two weeks to take effect, and it must be done within two or three weeks of the race, lest it wear off too soon.
But it's not easy for elite athletes to work heat training into their schedules.
"The problem is that it compromises your training, because you can't run at the speeds or [distances] you need to," Williams said.
One solution, he added, is for endurance-sport athletes to also incorporate altitude into their regimens.
"Altitude allows your body to develop more red blood cells," Williams said. Those extra blood cells carry more oxygen to the muscles, allowing them to work with less effort, he said.
"The athletes who are altitude prepared and who are very physically well conditioned will probably do best."
Before the U.S. track-and-field Olympic trials earlier this month, Yoder Begley and teammates trained in Park City, Utah, which sits about 7,000 feet (2,100 meters) above sea level.
When at home in Oregon, the runners are roughly at sea level, so they use sleeping chambers that mimic higher elevations with reduced oxygen levels.
Dust and Smog
Not every athlete is worried about heat. Sprinters don't mind, for example, because their races are too short for there to be any risk of overheating. For them, heat keeps their muscles loose, reducing the risk of muscle pulls.
But nobody is looking forward to Beijing's expected dust and pollution—especially since training for these conditions is not an option.
Conventional coaching wisdom holds that human lungs don't adapt to poor air quality. If people try, they may instead find that some pollutants accumulate from repeated exposure.
"Typically, for particles that deposit in the upper respiratory tract, clearance will take place within a 24-hour period," said Kent Pinkerton, an inhalation toxicologist at the University of California, Davis.
Smaller, more deeply penetrating particles are likely to persist longer.
"Particles that penetrate deeper into the lung could be retained anywhere from a few days to months," Pinkerton said.
And carbon monoxide, a common air pollutant from car exhaust, is much more likely than oxygen to bind with hemoglobin—the oxygen-carrying molecule in red blood cells.
So breathing automobile fumes today won't make athletes better able to cope with it tomorrow. The exposure may even leave them worse for the wear if the effects haven't worn off by the time they reach Beijing.
"We have to be extremely careful and steer [athletes] in the right direction," Randy Wilbur, lead exercise physiologist with the U.S. Olympic Committee, told the International Herald Tribune.
"Because if they thought locking themselves in the garage with the car running would help them win a gold medal, I'm sure they would do it."
Steering people in the right direction means telling them to keep away from the most polluted areas for as long as possible and encouraging them to wear dust masks when they can, experts advise.
"One thing that is in the favor of the athletes is that they are in peak form," UC Davis's Pinkerton added. As a result, he said, they will probably experience less of an impact than a young child or someone with existing heart or lung problems.
"Dust and pollution—there's nothing we can do about that," U.S. Olympian Yoder Begley said.
"Everyone's going to be in the same boat, and we're just going to try to stay out of it as much as possible prior to the race."
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