Low pressure has high impact on athletes

Cyclist Shaun Wallace thought he had a head start on much of his competition after he had a hypobaric chamber delivered by forklift to the Olympic Village at the 1996 Olympics in Atlanta, Ga. (1,050 feet above sea level).

Wallace, then 34, placed 16th in the 1,000-meter time trial event and credited the chamber — which creates a low-oxygen environment that simulates the effects of living at altitude — with much of his success. But the bulky chamber wasn’t exactly portable. So Wallace, who has a background in mechanical engineering, decided to fix that.

Thus was born the altitude tent.

The tents, most of which sell for roughly $4,000, are usually used at night, covering a bed like a cross between a mosquito net and a boy-in-a-bubble environment. A user manipulates oxygen levels by selecting an “elevation.” Hardcore enthusiasts can log additional daytime hours, working or napping — or, if they also have a mask system, exercising.Hypobaric chambers, which remove oxygen — and similar normabaric hypoxic tents, which replace normal air with lower-oxygen air to retain normal pressure — have developed a dedicated following. It’s harder to breathe in high altitude, and that’s exactly the point.

With a wide range of products on the market, the tents have caught on among professionals and amateurs alike: Wallace estimated that 70 percent of artificial hypoxia users are amateurs and that seven of the top 10 in a recent Tour de France were customers.

It’s a new way to achieve a longstanding goal: As early as the 1968 Summer Olympics in Mexico City (7,350 feet above sea level), it became clear that altitude training could dramatically improve performance.

When, for example, Kip Keino, from the hills of Kenya, beat world record holder Jim Ryun in the 1,500-meter race by the largest margin in the event’s history, athletes quickly realized that it might be in their best interest to relocate to higher regions.  The conventional wisdom held that because low levels of oxygen force the body to produce more oxygen-carrying red blood cells, training at altitude could produce surprising bursts of energy at sea level.

In 1997, Dr. Benjamin Levine published a seminal study on the idea of “living high, training low.”  He examined 39 competitive runners split into three groups: live high-train high, live low-train low and live high-train low.  The last group gained the most speed over the 10-week period, which could be explained by the physiological gains from spending most of their rest time accumulating extra blood cells, plus the fitness gains from working in an environment where they could push themselves without becoming exhausted quickly.

“It’s a form of natural blood doping, if you will,” Levine said.

Even before  Levine’s study, Wallace had been intrigued by altitude training.  Before the 1984 Olympics in Los Angeles, Calif. (233 feet above sea level), he moved to Colorado Springs, Colo. (6,035 feet above sea level) for a few weeks.  As a member of the British national team, though, he could not use the U.S. Olympic training facilities. He abandoned the plan until 1991, when he rented a cabin on the mountain and drove downhill to train.

After finishing second at the World Championships in 1991 and 1992, he bought his first chamber three years later and then devised the less expensive altitude tent, selling the first few to friends for $5,800. He founded Wallace Altitude Tent Systems, then moved to Hypoxico and finally to Colorado Altitude Training, both previously existing hypoxia retailers.

It’s almost ironic, then, given its ties to Olympic history, that artificial hypoxia has been banned in athlete housing at the Olympics since 2000.  “That’s politics,” said Levine, “not physiology.”

A representative from the World Anti-Doping Agency confirmed by email only that hypoxic tents were not prohibited in general.

Heart patients can benefit from high-altitude methods, as well. The Einstein-Montefiore Medical Center in New York City uses Hypoxico’s hypobaric chambers to give patients a good workout without doing anything very high-impact.

But not everyone is quite so high on altitude tents.

David Nader, a 41-year-old cyclist from San Mateo, Calif. (15 feet above sea level), bought a Hypoxico tent a few years ago.  A clinical researcher with a background in exercise physiology who has been racing since 2000, he lasted only six months.

“It was actually really stressful, because at night when you are sleeping and recovering from training you’re actually imposing an additional stress on your body,” he said.  “I started getting sick a lot.  So it ended up hurting me.”

Jenny Slawta, a 47-year-old associate professor of health, physical education and leadership at Southern Oregon University (1,895 feet above sea level),also  experienced some side effects, but with much more positive results.

Her performance at the annual Mount Evans Hill Climb in Colorado — the highest paved road in North America at 14,200 feet — made it worth it for her.  She finished first overall in the women’s category, setting the record for 40-plus women’s by 17 minutes and beating the fastest time in the pro category by 30 seconds.

“So that was a pretty good year for me,” she said with a laugh.  “I knew I’d done it right.”

A number of sports medicine professionals affiliated with the American College of Sports Medicine agreed in interviews that they were uncomfortable speaking broadly in favor of or against artificial hypoxia, because the effects are so individual-specific.  No one cited specific health risks.

Although Levine supports the technique, he is wary of machines that simulate low oxygen levels.  Simply sleeping in an altitude tent is not enough, he said.  “You need at least 12 hours a night, if not more, to get enough hypoxic exposure to make the red cells go up,” he said.

Wallace agreed, adding a caveat: People who live at high altitudes cannot train as hard as their sea-level opponents.  “I think there’s little doubt that someone who uses an altitude tent for all of their sleeping hours has closed the gap on someone who lives in Colorado Springs,” he said.