Into thinner air
IT is 4:01 a.m. The red glow of the digital clock is clearly visible through the clear plastic walls surrounding my bed. It is mid-March, and the Boston Marathon is more than a month away. If everything works as planned, I will finish it in less than three hours.
For several nights now, I’ve been sleeping in a giant plastic bubble as part of an unscientific but increasingly common experiment on athletic performance. The air in the tent contains less oxygen than the air in the rest of Los Angeles. By using the tent for the next few weeks, I hope to improve my body’s ability to supply oxygen to my running muscles -- and shorten my marathon time.
Other hard-core runners, cyclists and cross-country skiers -- especially aging ones -- understand this desperate attempt to get faster. As bodies age, they need more training to achieve the same times, and at 36, I’ve already started to slow down -- at least 1 1/2 minutes over a 6.2-mile race compared with my college days.
Short of using performance-enhancing drugs, I’m willing to try almost anything for an advantage.
I’d move to the mountains if I could. Above 7,000 feet, where significantly less oxygen is available than at sea level, the body increases its production of oxygen-toting red blood cells within a few weeks.
In races at sea level, athletes with extra red cells can supply their muscles more efficiently with oxygen than their competitors from the lowlands.
The promise of such a boost draws top endurance athletes to live in oxygen-thin places, such as Boulder, Colo., or Mammoth, Calif. But for the rest of us, trapped in desk jobs at sea level, a tent filled with oxygen-thin air is a tempting alternative.
In theory, spending a large portion of each day in a low-oxygen environment can trick the body into producing extra red cells.
Research even suggests this might be more effective than simply living and training in the mountains. “Live high, train low” goes the current mantra on altitude for athletes. Living high builds up the red cell count. Training at lower elevations allows the body to exploit those cells by pushing your body as hard as possible; it is simply not possible to run as fast at high altitude.
Inside the tent, I cannot get back to sleep. And because I’m not yet acclimated, it feels hard to breathe.
I think of a John Travolta TV movie from 1976, “The Boy in the Plastic Bubble,” in which he plays a kid with an immune system disorder who stays alive by living in an incubator.
At least my immune system is fine.
Over the last decade or so, tents and other types of altitude chambers have become standard equipment for many elite runners, cyclists and cross-country skiers.
Lance Armstrong was one of the early believers. Now it is hard to find a Tour de France rider not sleeping “at altitude.”
Using the same technology that pumps oxygen-poor air into the tents, Nike has turned an entire house into a high-altitude dormitory for its running stars in Portland, Ore.
Horse trainers have even started boarding thoroughbreds in stalls filled with oxygen-thin air.
The technology has become so popular that last year the World Anti-Doping Agency, which sets the rules on performance aids for international competition, considered adding altitude tents to its list of “banned methods.”
In theory, the tents have the same effect as injecting EPO, an artificial version of the hormone erythropoietin, which stimulates red blood cell production in people suffering from anemia. It has long been banned in sports.
The case against tents came down to the question of whether they “violated the spirit of sport.” Ultimately, the answer was no, tents were simply another training aid.
Not only the elites are using them.
Amateurs account for about half of the several thousand people who have bought altitude tents, according to the two companies that control the U.S. market, Colorado Altitude Training in Boulder, and Hypoxico Inc. in New York.
The most affordable way to try a tent is renting, for about $600 a month. Buying a tent requires more commitment: A basic model sells for $6,000.
Converting a bedroom into an altitude chamber runs more than $20,000.
Since I was already training hard, it seemed unlikely that sleeping at simulated altitude could help much. But Hypoxico agreed to lend me a tent for five weeks before the Boston Marathon.
The marathon would be the main test.
Of course, many things can go wrong in a long race -- hot weather or just an off day -- so I decided to gauge the tent’s effects another way.
Before I started using it, I did a “lactate threshold test,” which involves running on a treadmill at ever-increasing speeds while a technician periodically pricks your finger for a blood sample. The test measures the body’s ability to process lactic acid -- which accumulates in the body as muscles tire -- and is considered an excellent measure of aerobic fitness.
I would redo the test around marathon time.
The tent arrived at the Los Angeles Times mailroom in two boxes weighing a total of 85 pounds.
The smaller box contained the tent, the “king-size.” I unrolled it in my bedroom and set it up in about 30 minutes.
The arching roof was nylon and the sides were clear plastic, with zippers. It looked like a giant version of the packages that pillows and blankets come in, the kind that say, “Keep away from children: could cause suffocation.”
The whole bed probably could have fit inside, but it was easier to just slide the mattress onto the tent’s floor.
The second box, the heavy one, held the generator -- the deluxe model, allowing for an oxygen level equivalent up to 12,500 feet. A cheaper model goes to 9,000 feet, which the company says is sufficient for everybody except mountain climbers.
The generator takes in normal air -- which at sea level contains 20.9% oxygen -- and pumps out a new mix of air into a clear plastic hose running into the tent.
I attached the hose, plugged in the generator and hit the blue start button. The generator rumbled like an old car. Fortunately, the hose was long enough to keep the generator in the next room.
That night, I set the dial at 4,500 feet, an altitude equivalent to that just below Carson City, Nev., an oxygen content of about 17.7%. The company had advised me to start low and build up to 9,000 feet or 15%, over the course of a week. Going up too quickly could cause headaches and fatigue.
I climbed inside and zippered the door shut.
The end of the hose was breathing. Heavily, like Darth Vader or someone with a respiratory disease.
I would get used to it.
But the tent should come with a warning: Your significant other might not like this.
“If you want to have any kind of relationship, you’re going to have to get your partner to agree,” advised David Nader, 37, an amateur cyclist from San Francisco, who bought a tent in January.
“I think she’s trying hard to be supportive,” he said of his wife. “Sometimes she sleeps in the guest room.”
Nader, who rides more than 200 miles a week and races about 25 times a year, is hoping the tent will help him move up in the local rankings.
“It’s been really tough to tell whether it’s making a difference,” he said.
Part of the problem is that he has had to travel for his job managing clinical trials for a biomedical company. Only recently has he been sleeping in the tent consistently. My girlfriend stayed over on the second night.
I offered to leave the dial at 4,500 feet to let her acclimate, but she insisted on going to 5,000 feet, just below Albuquerque, N.M.
She never admitted it, but I think she hoped the tent would help her swimming.
Hypoxico said it would take three to four weeks to see results, suggesting that I could improve my performance by 2%. I ran my last marathon, in Chicago in October 2005, in 3 hours, 3 minutes, on far less training than I was doing now. A 2% improvement would equate to about 8 seconds a mile, or 3 1/2 minutes over the entire 26.2 miles of a marathon.
The science behind that potential improvement, I later discovered, is far from conclusive.
Live high, train low
The seminal study on altitude training, published in 1997 in the Journal of Applied Physiology, set up various training camps for 39 competitive runners. Well-trained runners who lived at 8,200 feet and trained at 4,100 feet showed an average improvement of 1% to 2% in a 3.1-mile run at sea level. In contrast, runners who lived and trained at 8,200 feet -- or those who lived and trained at sea level -- did not improve in the sea-level time trial.
Both high-altitude groups increased their red blood cell production.
That study, which gave rise to the live high, train low philosophy, is the one cited most frequently by the tent manufacturers.
But the lead author, Dr. Benjamin Levine, a cardiologist who leads the Institute for Exercise and Environmental Medicine at Presbyterian Hospital of Dallas, said his results should not be interpreted as evidence that the tents work.
A key issue is how many hours a day an athlete spends in an oxygen-thin environment. A normal night’s sleep may not be enough.
The runners in Levine’s study spent 20 to 22 hours a day at high altitude, in Deer Valley, Utah, traveling down the mountain each day for training in Salt Lake City.
“We think you need at least 12 to 16 hours a day,” Levine said.
Only a few controlled experiments have been performed using simulated altitude. A 1999 study published in the journal Medicine and Science in Sports and Exercise showed that red blood cell mass increased in athletes who spent 16 hours a day in a low-oxygen house.
The same year, Australian researchers publishing in the European Journal of Physiology and Applied Physiology concluded that “live high, train low” did not change the red cell mass in male endurance athletes who spent 23 days sleeping 8 to 10 hours a night in an altitude house set to 9,800 feet.
The researchers found small improvements in anaerobic performance -- bursts of effort when muscles work at very high intensity. But they could provide no clear mechanism to explain their results.
Adding to the scientific uncertainty, there appears to be great individual variation in who benefits from living at altitude, simulated or real. Some people don’t seem to respond to long “doses” of altitude and others benefit with shorter exposures, Levine said.
“We think it’s genetic,” Levine said.
Each night, I fell asleep wondering if my red cells were multiplying.
Over the first week, I turned the dial up each night until I reached the recommended 9,000-feet oxygen level. Using a flashlight, I checked an oxygen meter to verify the concentration inside. It was on target at 15%.
One night, my girlfriend brought over her dog. Although not the most athletic canine, he appears to be part Bernese mountain dog. Maybe he would enjoy the tent. Maybe he would get faster -- or at least not sit down halfway through his walks.
He wouldn’t come in. Once we zipped up, he peered in at us through the plastic, his breath fogging the door.
Although a triathlete friend of mine seemed jealous when I told him about the tent, part of me began to wonder if I was betraying the sport of running. What I’ve always loved about it is its simplicity. All you need is a decent pair of shoes.
But it seems unlikely that tents or altitude rooms will become standard equipment for athletes.
Sleeping in the tent is not fun even for a few weeks, much less month after month, year after year, as some athletes have done -- all in hopes of shaving mere seconds off their times.
The tent is hot, especially when two people sleep in it. Some mornings, dew had accumulated on the plastic walls. And sometimes I woke up tired and dehydrated, reaching for the water bottle beside the mattress. Occasionally I discovered I’d lost a couple of pounds overnight.
And there were times I couldn’t bring myself to hit that start button and zip the door -- especially if I had a long run scheduled for the morning and needed to be especially well-rested. I never slept as well in the tent as I did without it. Fortunately, Hypoxico said that five days a week was sufficient.
At least after a week of acclimatization, I could breathe easily.
But I won’t miss the tent and neither will my girlfriend. She sometimes experienced headaches, and she’s not sure if she can swim any faster.
As for me, in the few weeks before the marathon, I ran 5 seconds per mile faster than I ever had for my standard 4.4-mile loop in Griffith Park.
A second treadmill-blood test, after five weeks of using the tent, showed that my body could clear lactic acid faster than before. The test suggested that I should be able to run each mile of the marathon 9 seconds faster.
Was it the tent? Maybe. But I’d also been training harder than I had in years.
I had followed a detailed plan, logging hundreds of miles in a few months. I tried to get enough sleep and eat the right foods. I developed a pacing strategy for the race. But some things you can’t control.
A variable comes into play
A nor’easter storm hit Boston the day before the marathon and continued through the race, pounding the runners with cold rain and 25 mph headwinds most of the way.
For the first half of the race I stuck to my plan, averaging 6:34 minutes per mile. But I spent too much energy fighting the winds and burned out in the second half of the race. By 21 miles, I was simply trying to finish. The leaders were already done, but they had suffered too. The winning time was the slowest in 30 years.
I wobbled over the finish line in 3 hours, 8 minutes and 5 seconds.
Shivering with a mild case of hypothermia, I knew I had to get warm. Somebody took my elbow and guided me toward the medical unit.
It was a giant, white tent.