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CHAPTER 11
TRAINING AT ALTITUDE—
Outdoor and “Indoor” Benefits
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For many years, training at altitude has achieved a certain mystique. Cities like Boulder and Flagstaff have blossomed into endurance meccas. But their appeal, like any other high-altitude locale, is not the magic ingredient for the improved endurance many seek. In fact, having personally spent time in these locations with many athletes during my coaching career, and observing firsthand how many others train, it’s clear that the risk of overtraining is very high.
Even the moderate elevations of 3,000 feet in altitude can increase the training heart rate by several beats or more for several days or even weeks, depending on the individual. If training is based on pace rather than heart rate, most athletes end up working out too hard, too often. This is mostly due to the “thinner” air, which really means the lower barometric pressure at higher altitudes reduces the ability of the body to take oxygen out of the air into the capillaries of the lungs, so it’s now in the bloodstream. In addition to higher resting and training heart rates, recovery can be significantly reduced.
Just being in a pressurized cabin of a commercial airliner is the same as being at 6,000 to 8,000 feet (1830 to 2440 meters) even though the plane may be flying at 30,000 feet. As soon as you step off the plane and arrive at a high-altitude location, your body is exposed to significant stress; in addition to thinner air, your training performance is also reduced dramatically. Furthermore, reduced food intake is common, which may not match your energy expenditure needs—a form of nutritional stress. Moreover, there is much less moisture in the air, and the risk of dehydration must be avoided. Ascending to higher altitudes can be such a stress that a condition called acute mountain sickness can follow in some athletes, resulting in headache, nausea, insomnia, and malaise. You don’t have to be that high above sea level either, as even skiers, for example, visiting resorts at 6,000 feet can have this condition
Your body will compensate for the stress of altitude, at least the oxygen-debt aspect, partly by increasing your heart rate and breathing rate, enabling you to carry more oxygen. Over time, the kidney makes more of the hormone EPO (erythropoietin), which stimulates the bone marrow to make more red blood cells, and larger ones, for further compensation. This increases the body’s ability to bring oxygen to the muscles. After about three weeks at altitude, these and other adaptations result in better oxygenation, perhaps closer to sea-level conditions.
Eventually, after several weeks and depending on your body, because everyone responds differently, all this compensation enables you to train without the stress encountered when you first arrived at altitude. However, there are benefits to being at altitude. “Thinner” air means less physical resistance during a workout or race. This is due to reduced moisture in the air. So cycling and skiing performance, for example, can improve only after—not before—you have adapted to the altitude. Once these changes take place, and the athlete returns to lower altitudes, such as sea level, the increases in red blood cells and associated increased oxygen carrying potential may increase performance.
With sufficient time, higher altitude training comes with other benefits. But the real advantage is in living there long enough—such as three or four months—and not necessarily in the training. The worse scenario is visiting the mountains for only a couple of weeks thinking it will help your training—but that’s not sufficient time for your body to make the necessary adjustments. One result of spending adequate time at altitude is that you produce more oxygen-carrying red blood cells and higher hemoglobin from increased EPO. While these benefits are good for your health, they only significantly improve your fitness when you return to lower altitudes to compete.
Returning to sea level three weeks before a major race offers the best of both altitudes. First, when descending to a lower altitude your oxygen uptake is greater. And second, you maintain the improved oxygen-carrying capacity developed during your time at altitude, which helps you in competition. These changes disappear quickly after a month or so at lower altitudes, but the approach is very effective. This was one of Mark Allen’s strategies when he won six Ironman Hawaii races. Each summer he would spend several months living and training in Boulder.
All these potential changes and responses by the body are also individual. Some respond better to altitude while other have a difficult time. The overall levels of fitness and health may be the most important factors, with a variety of specific dietary, nutritional, and stress factors being necessary to obtain benefits at altitude. For example, if your ability to make red blood cells is impaired due to low folic acid or iron levels, being at altitude won’t help. This does not mean you should take an iron supplement if you’re going to train at altitude. Consuming a healthy diet, sufficient in iron, will provide your body with the amount of iron needed to make appropriate levels of red cells. And when going to altitude, the body automatically adjusts by absorbing three to four times more iron from your diet (like with most nutrients, the brain and body know just how much you need to take from your food as it passes through the intestines). Taking iron supplements when you’re not anemic can be dangerous as it can cause significant chemical stress and even physical stress on the intestines.
Biking outside Boulder—a high-altitude mecca for endurance athletes
For many athletes, going to altitude for some period of time often results in extra stress while the body is adapting to the changes induced by altitude. This is shown by an increase in the stress hormone cortisol, which is produced as a result of any stress—including an environmental one like altitude. Adrenal stress not only can raise cortisol to unhealthy levels but also reduce other adrenal hormones, notably aldosterone, which can result in poor electrolyte and water regulation. One requirement of training at a higher altitude is wearing a heart-rate monitor and remaining aerobic for the first few weeks. This will help you obtain the potential benefits of altitude training while diminishing the risks.
In addition to improved changes in blood chemistry, other potentially healthy changes may occur in aerobic muscles while living and training long enough at altitude. These include increased circulation in aerobic muscles, increases in myoglobin (the red pigment in aerobic fibers) and aerobic enzymes to help with fat burning, and improvements in lactate metabolism.
The particular altitude effects vary with the ascent, with higher altitudes producing better results. It’s difficult to say what that magic altitude is because of individual variation and positive and negative effects of various altitudes. For example, red blood cell responses may be better at an 8,000-foot altitude compared to 5,000 feet, but other stresses exist at the higher levels, such as the increased risk of dehydration and even lower oxygen uptake slowing your training pace. Altitudes between 4,000 and 7,000 feet may be the best general range for potential improvement in fitness and health, if you’re already fit and healthy, you train with a heart-rate monitor adhering to the maximum aerobic heart rate based on the 180 Formula, and you carefully assess your progress and avoid entering the first stage of overtraining.
The benefits of training at altitude are not just physiological. The enjoyment of being in most moderate-level mountainous regions is socially and psychologically rewarding. Whether in the Rocky Mountains, for example, or many other areas around the world, these locations offer a healthy, lowstress place to train and live compared to hurried, tension-ridden areas around New York, Los Angeles, and similar locales. Moreover, the summer weather in these mountain areas offers the additional benefit of being cooler without very high humidity. This social and psychological enjoyment may help offset some of the other stresses.
