Serbian tennis star Novak Djokovic hasn't earned his No. 1 ranking by taking the conventional road. There's his odd ritual of excessive ball bouncing before serves, which can break an opponent's concentration. There's his new gluten-free diet, which he's said has helped him feel stronger on the court.
But now there's something truly weird: the CVAC Pod.
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Ever since last year's U.S. Open, Djokovic has been trying to improve his fitness by climbing into a rare $75,000 egg-shaped, bobsled-sized pressure chamber.
The machine, which is made by a California-based company called CVAC Systems and hasn't been banned by any sports governing bodies, is one of only 20 in the world. Unlike the increasingly trendy $5,000 hyperbaric chambers many professional athletes use to saturate the blood with oxygen and stimulate healing, the CVAC is a considerably more-ambitious contraption. It uses a computer-controlled valve and a vacuum pump to simulate high altitude and compress the muscles at rhythmic intervals.
The company claims that spending up to 20 minutes in the pod three times a week can boost athletic performance by improving circulation, boosting oxygen-rich red-blood cells, removing lactic acid and possibly even stimulating mitochondrial biogenesis and stem-cell production.
Djokovic has never mentioned the pod publicly before. He acknowledged using it for the first time last week during a sponsor event in New York after he was asked about it for this article. "I think it really helps—not with muscle but more with recovery after an exhausting set," he said. "It's like a spaceship. It's very interesting."
CVAC says its pod is different from other pressurized chambers on the market because it combines altitude pressure with cyclic compression. Because the pressure, temperature, air density in the CVAC pod can be adjusted, the company says it enhances an athlete's ability to adapt to a range of conditions.
CVAC Systems chief executive Allen Ruszkowski says the treatment seems to have many of the same effects on the body as intense exercise. He claims that the technology may be twice as effective at helping the body absorb oxygen as blood doping—a banned form of performance enhancement.
Former U.S. Olympic wrestling coach Bob Anderson, motocross racer Ivan Tedesco and ultra cyclist George Vargas say they've used the pod and believe it helps. CVAC's Ruszkowski says a slew of other high-profile athletes use the Pod but often insist the company doesn't tell anyone, "because they feel it's a competitive advantage.".
Djokovic and other players who know him say he's a visionary obsessed with cutting-edge performance technologies. "He loves to explore the future of athletic edges—and he has the resources to do it," says former top-20 player Vince Spadea who hit with Djokovic in Alpine last summer when he says Novak was first "experimenting" with the pod at Uehling's estate. "He was looking to improve some of the challenges he was having—breathing capacity, allergies—and definitely something clicked there."
Spadea says he didn't dare set foot in the pod himself because he doesn't share Djokovic's "daredevil mentality." Djokovic's Serbian countryman, Janko Tipsarevic, currently ranked No. 20, says he's heard about the pod but hasn't tried it yet, either.
Geoff Grant, tennis director at at Tenafly Racquet Club, says he braved the pressure chamber at Uehling's request and felt like he was taking off in an airplane as his ears popped. He says he hasn't used it enough to notice a difference in his play, but adds that some of his clients who go more regularly are hooked and "say it's like a drug."
"It's weird—it's definitely something from the future," Grant said last week at the racquet club. "I think Novak was going to get in it today."
In 2006 the World Anti-Doping Agency ruled that such oxygen tents enhance performance and violate "the spirit of sport," but did not add them to the list of banned substances and methods, saying they would wait until further studies were conducted.