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  • Altitude Training for Athletic Success - Part I

     Gale Bernhardt ©2018

    If you are a lowlander and have traveled to the mountains to bike, hike, ski, race, or sightsee, you may have experienced uncomfortable symptoms of high altitude. You may have gotten a rip-roaring headache, nausea, or just felt lousy all over. Still, you have heard that high-altitude training is “good” for you. Is altitude training really worthwhile?

    In this column I will explain the basics about how altitude affects the body, the benefits and the downsides. In Part II I’ll look at some recommendations for utilizing altitude training for sea level racing and for mountain racing.

    The reality is, the density of oxygen in the air decreases in direct proportion to increasing altitude. In other words, when you take a normal breath of air at altitude, you will have less oxygen in your lungs than you would if you were to take the same size breath at sea level. Being an aerobic animal, you know your muscles want and need plenty of oxygen for endurance sports. To compensate for less oxygen and reduced pressure, the body tries to adjust, occasionally rebelling. The most important compensations include an increase in breathing rate (causing some people to hyperventilate) and an increase in blood flow at rest and during submaximal exercise.

    Additional responses to changes in altitude can include increased resting heart rate, lightheadedness, headache, insomnia, nausea, and loss of appetite. As altitude increases above 15,000 feet, people may experience vomiting, intestinal disturbances, dyspnea (labored breathing), lethargy, general weakness, and an inability to make rational decisions.

    In the first few days of altitude adaptation, cardiac output and submaximal heart rate may increase 50 percent above sea level values. No wonder people feel like their hearts are going to leap from their bodies! Because your body requires the same amount of oxygen to work at altitude as it does at sea level, the increase in submaximal blood flow partially compensates for reduced oxygen levels.

    In terms of total oxygen circulated in the body, at rest and moderate levels of exercise, a 10 percent increase in cardiac output can offset a 10 percent reduction in arterial oxygen saturation. In other words, your heart can pump 10 percent faster to compensate for 10 percent less oxygen in your bloodstream

    It is beyond the 10 percent range where things get tough. The greatest effects of altitude on aerobic metabolism seem to be during maximal exercise. At top intensities, the ventilatory and circulatory adjustments to altitude cannot compensate for the lower oxygen content of arterial blood. This means the athlete has to slow down to reduce the demand for oxygen.

    Adaptations to Altitude Stress

    With all the seemingly negative effects, why would someone want to train at altitude? The biggest reason to train at altitude is the body’s long-term adaptation, which is an increase in the blood’s oxygen-carrying capacity. This is partially due to an altitude-induced increase in erythropoietin (EPO), the key chemical that stimulates increased red blood cell production. Altitude exposure also causes an increase in 2.3 DPG, the chemical that makes oxygen more available to the muscles.

    During the first few days at altitude, there’s a decrease in plasma volume. Because of this decrease, red blood cells become more concentrated. For example, after about a week at 7,400 feet, the plasma volume is decreased by 8 percent, while the concentrations of red blood cells and hemoglobin are increased by 4 and 10 percent, respectively. The changes observed after a week cause the oxygen content of arterial blood to increase significantly above values observed immediately upon arrival at altitude.

    Following this adaptation of decreasing plasma volume is an increase in red cell mass. Through responses initiated by the body, reduced arterial oxygen pressure stimulates an increase in the total number of red blood cells. For example, a healthy high-altitude native may have a red blood cell count that is 50 percent greater than a native sea level dweller. These two adaptations to altitude have an effect that translates into a large increase in the blood’s capacity to transport oxygen at rest and during exercise.

    Speed and Power at Altitude

    Having lots of red blood cells that flood the body with oxygen-carrying capability sounds great, right? People ought to be aerobic animals after they adapt to altitude. But here’s the bad news: When exposed to higher altitudes, it’s nearly impossible for athletes to train at the same intensity as they were able to train while at sea level.

    In other words, if you are a lowlander capable of averaging 20 miles per hour for a 40km time trial, at a heart rate of 175 beats per minute and a perceived exertion of 17 on the Borg Scale (breathing hard), your average speed (assuming a duplicate course profile) could be decreased by 5 to 10 percent for the same heart rate and perceived exertion when exposed to even moderate altitudes. This means your speed will decrease by two miles per hour, which is quite a reduction.

    What if people who already live at high altitude travel to sea level? Is there an automatic gain in speed? That’s a good question, and there’s no easy answer. Since people living at a higher altitude are not able to train at the same intensity levels they would train at as lowlanders, they have not trained their bodies to perform at higher speeds. Unproven by science, perhaps the highlanders don’t have the neuromuscular programming, in addition to the metabolic speeds, necessary to cycle fast at sea level.

    How long is it before the benefits of high altitude disappear when that athlete travels to race at sea level? Estimates for an athlete to lose the maximum benefits of their native, high-altitude adaptations are in the six- to eight-week range.

    Up Next

    In Part II we’ll look at utilizing altitude to improve race performance.

    Portions of the text reprinted from “Training Plans for Cyclists” by Gale Bernhardt, VeloPress.

    Gale Bernhardt was the 2003 USA Triathlon Pan American Games and 2004 USA Triathlon Olympic coach for both the men's and women's teams. Her first Olympic experience was as a personal cycling coach at the 2000 Sydney Olympic Games. Thousands of athletes have had successful training and racing experiences using Gale's ready-to-use, easy-to-follow training plans. For more information, find some plans on Gale’s site and more plans on TrainingPeaks.com.  

     

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