According to High Altitude Living, “[p]eople may feel effects from higher altitudes as low at 4000 ft above sea level. Usually by 6000 ft, they will experience more fatigue, and a greater potential for dehydration.” These effects occur because the air is thinner at higher altitudes, which creates an oxygen deficit that can inhibit regular physical activities-until one’s body adapts to the higher altitude.
Imagine, then, how much more difficult this oxygen-differential can be for those who exercise at altitude.
Exercising at Altitude
Even top athletes will initially find it difficult to exercise at higher altitudes. They will feel the lack of sufficient oxygen with each labored breath, say experts, because their oxygen needs have not changed even though the altitude has changed, and the air has become thinner.
But the body is an amazingly adaptive machine that, in time, becomes acclimated to exercising at altitude by producing some physiological changes.
Physiological Adaptations to Higher Altitudes
Because oxygen is thinner at higher altitudes, one must breathe faster in order to obtain the same amount of oxygen as experienced at sea level. This increased breathing rate is necessary to supply sufficient oxygen to the blood stream, which then sends it to the oxygen-dependent muscles. The heartbeat simultaneously increases in an effort to transport oxygen throughout the body, via the bloodstream.
Studies have shown that in just a few days, however, the lungs become extremely efficient at breathing this thinner air. Several studies, for instance, have shown that the volume of air that the lungs are able to accommodate eventually doubled in those exercising at altitude from 12,000 to 14,000 feet.
Other physiological adaptations that the body makes to higher altitudes include:
– A higher heart rate required to move the disease amount of oxygen throughout the body. Within a few days, however, the increased blood that is pumped through the heart decreases, as does the heart rate. In a very short time, both the blood volume pumped by the heart and the heart rate decrease to the levels of those that were present at sea level.
– An increased number of red blood cells, which enables greater oxygen transportation by the blood stream. (One study showed that as subjects became accustomed to the higher altitude of 13000 feet, their blood/oxygen levels increased by 19 percent while the blood volumes processed by the heart decreased by 9 percent.)
– Chemical enzyme changes. Of particular interest to an athlete is the performance of the muscles, performance that is significantly affected by chemical enzymes, which supply necessary energy to the muscles. As the body becomes accustomed to higher altitudes, these enzymes adapt to the lower oxygen rate, per experts, and perform much as they did at sea level.
What these physiological changes mean for those regularly exercising at altitude, according to New York Times sports reporter William Stockton, “is a steady improvement in [exercise] performance. (The) heart rate begins to decline [for the same amount of effort] and breathing becomes less difficult.”
The athletic-enhancing benefits of exercising at altitude are so well known that many coaches recommend this type of training to their athletes. There are, however, certain dangers that can accompanyy such training.
One of the chief dangers is Acute Mountain Sickness, AMS (also called altitude sickness.) AMS is the body’s effort to acclimate to the reduced oxygen levels at higher altitudes. As previously mentioned, during the acclimatization process one’s breathing rate increases in an attempt to obtain additional oxygen. In some individuals, this process can lead to hyperventilation symptoms such as shortness of breath, dizziness, nausea, and headache. These symptoms can be extremely distressing and even debilitating.
Although most cases of AMS are minor, with a small percentage of those afflicted, a potentially life-threatening condition called high-altitude pulmonary edema (HAPE) may develop, which is caused by the leakage of fluids from the blood vessels into the lungs. The first symptom of HAPE is usually an extreme shortness of breath that occurs simultaneously with ascension to a higher altitude. Shortly thereafter, the heart rate and the breathing increase and a cough develops that sometimes contains bloody sputum. By the time that these symptoms appear, quick medical attention is necessary to prevent the sufferer from lapsing into a coma and dying.
Still another form of AMS, and one that is even more dangerous, is called high-altitude cerebral edema (HACE). Although the exact mechanism whereby this disorder develops is not completely understood, it usually begins with the classic symptoms of AMS and then progresses into neurological symptoms such as speech impairment, loss of coordination, alternated states of consciousness, and hallucinations which eventually lead to death if medical attention is not immediately administered. Although HACE is very rare, it is a high-altitude risk that cannot be ignored.
Tips for Exercising at Altitude
To minimize such potentially dangerous medical conditions, and to manage any unpleasant physical symptoms caused by ascending to higher altitudes, experts recommend these tips:
– Make the ascension slowly. If possible, allow your body a full day to acclimate to the altitude change of moving from 4,000 to 5,000 feet and a similar time period to acclimate to the change from 8,000 to 12,000 feet.
– Watch your training schedule. Make sure that you train slowly to allow your body time to adjust to the higher altitude.
– Stay hydrated. Higher altitudes can lead to a greater risk of dehydration if sufficient amounts of water are not consumed. Experts recommend that drinking a minimum of 8 ounces of water for every 20 minutes spent exercising at altitude.
– Listen to your body. If the intensity of your exercise program is causing your breathing to become excessively labored, reduce the intensity until your breathing eases. (Because of this acclimation process, you will likely have to adjust your exercise program many times until full acclimatization is achieved.)
Exercising at altitude is a productive training method that one should attempt only when fully apprised of and prepared for the attendant risks. If an athlete adequately prepares, and is cognizant of the potential deadlier risks, and thus adjusts his or her training schedule accordingly, the athletic benefits of exercising at altitude can be enjoyed without incurring the dangerous side effects.