SWEAT SPOT by Alex Voetsch

THE JOCK Dathan Ritzenhein
THE WORKOUT Antigravity treadmill
THE BENEFIT Extra mileage without extra stress

For a world-class distance runner, 6,000 miles a year is the toll for staying competitive. Unfortunately, all those miles add up to a litany of stress fractures, fatigued muscles and other debilitating injuries. "Staying healthy is half the battle," says U.S. Olympian Dathan Ritzenhein (right), who's currently training for the '08 Marathon. After developing a stress reaction in his left foot last March, Ritz bought a G-Trainer antigravity treadmill from California-based outfit Alter-G. With its NASA-developed technology, the G-Trainer creates a differential in air pressure—kinda like a vacuum—that supports up to 90% of the user's weight, thereby considerably lowering stress on the legs. Ritzenhein logged up to 130 miles a week on the treadmill during his rehab. Now healthy, he boosts 100 weekly road miles with 20 to 30 more on the G-Trainer. "When I'm hurting, I set it to a support level that lets me run without pain, then decrease it as I heal," he says, noting that the $75,000 unit has been a boon to his Beijing prep. If only it could help him adjust to smog.