This article was originally published in the Jan/Feb 2011 issue of Inside Triathlon magazine.
Boulder, Colo., became an endurance Mecca in the 1970s, after exercise scientists discovered that living at high altitude changes blood chemistry in ways that enhance sea-level performance. Since then, exercise scientists have learned a great deal more about the relationship between altitude and endurance performance, and what they’ve learned suggests that Boulder’s mile-high elevation is one of the worst possible environments for endurance athletes to make their homes in. It’s not high enough to significantly change blood chemistry in most people, yet it’s also just high enough to significantly reduce performance in high-intensity workouts, so that athletes get a little less benefit from each quality session.
Forgive me if you’re reading this in Boulder. We’re just the messenger.
If you want to get mad at someone, get mad at Robert Chapman, an exercise physiologist at Indiana University and one of the world’s leading experts on the effects of altitude exposure on endurance performance. Chapman explains that the key thing his colleagues had wrong in the 1970s was the specific effect of training (versus living) at altitude on endurance performance.
“Historically, people had thought that training at altitude was beneficial for sea-level performance,” he says. “Slowly, over time, we started to realize that’s not necessarily the case. For many people, training at altitude is actually a negative, and it’s mainly because they train slower when they’re at altitude. And they also train at a lower oxygen uptake, so there’s less adaptive stimulus.”
The problem with training slower at high altitude is that it causes the neuromuscular system to miss out on some of the performance-boosting adaptations, including increased efficiency, that come from going faster. The problem with training at lower oxygen consumption levels is that it causes the metabolic system to miss out on some of the performance-boosting adaptations that come from consuming more oxygen. For example, high levels of lactate production during intense exercise stimulate the biogenesis of new mitochondria within muscle cells, which increases aerobic power. But fatigue occurs at lower blood lactate levels at high altitude. Not good.
According to Chapman, some athletes do experience an overall improvement in sea-level performance after a period of living and training at high altitude. But the gain comes entirely from the living at altitude part rather than the training at altitude part. The training at altitude part actually negates some of the potential gain they get from the living at altitude part. Meanwhile, the other half of the endurance athlete population experiences a net loss in sea-level performance as a result of living and training at high altitude.
Live High/Train Low
In the 1990s, the revelations about altitude led exercise scientists James Stray-Gundersen and Ben Levine to propose an alternative way to use altitude to increase endurance performance. This alternative became known as “live high/train low.” As the name suggests, this model entails living at high altitude to stimulate increased red blood cell production—which enhances endurance performance by boosting the blood’s capacity to deliver oxygen to the working muscles—and working out at low altitude, allowing the athlete to actually take advantage of those extra red blood cells to perform faster workouts that stimulate stronger fitness adaptations.
Stray-Gundersen and Levine tested their new model in a seminal 1997 study involving 39 college runners. They separated these runners into three groups. For 28 days, one group lived and trained at high altitude, a second group lived and trained at sea level, and a third group lived at high altitude and trained at low altitude. At the end of the period, both the live high/train high runners and the live high/train low runners exhibited increased red blood cell counts. But only the live high/train low runners showed improved performance. On average, these runners ran 13.4 seconds (or 1.5 percent) faster in a 5000 meter time trial after the intervention than before, while 5000 meter performance was unchanged in both the live high/train high and the live low/train low groups.
In tabular form, the results look like this:
Protocol Performance Improvement
Live Low/Train Low 0%
Live High/Train High 0%
Live High/Train Low 1.5%
Now, these are average results, and as such they mask the fact that some athletes do improve by living and training at high altitude, while others go backward. Chris Lieto finished second in the 2009 Hawaii Ironman after his first stint of living and training at high altitude in Mammoth Lakes, Calif. Although he did not engage in formal performance testing to prove that it worked, he says, based on subjective measures, “I feel it worked well.”
However, according to Chapman, even the fraction of the endurance athletes that benefits from living and training at high altitude is likely to get better results from live high/train low. That’s because they will get the same increase in red blood cell mass from living at high elevation while being able to perform at a higher level in workouts at lower elevation.
The only drawback of live high/train low is that it is terribly inconvenient. It requires that one live at an elevation of at least 6,000 feet for at least four weeks and drive down to an elevation of 4,000 feet or below for workouts. There are only a handful of locations in the U.S. where this is possible. In the Stray-Gundersen and Levine study, athletes lived in Park City, Utah, and drove to Salt Lake City for workouts. One could also live in Flagstaff, Ariz., and drive to Sedona; live in Taos, N.M., and drive to Cloud Cross; live in Mammoth Lakes, Calif., and drive to Bishop; or live in Lake Tahoe, Calif., and drive to Sacramento or Reno, Nev. That’s about it. Live high/train low is not possible in places like the U.S. Olympic Training Center in Colorado Springs, which sits at an elevation of 6,200 but is not within a workable driving distance of any place below 4,000 feet.
The hassle of live high/train low is mitigated somewhat by Stray-Gundersen and Levine’s more recent discovery that it is not necessary to perform every workout at lower elevations to reap benefits. In a 2000 study, they found that elite runners improved their 3000-meter times as much when they lived at high altitude, performed all of their moderate-intensity runs at high altitude, and did only three high-intensity runs per week at lower elevation as they did when they lived at high altitude and performed all of their runs at lower elevation.