When Sir Roger Bannister, a neurologist and the first person to break the 4-minute mile, was asked what he thought it would take to become fully acclimatized to altitude he responded, “There are two ways. Be born at altitude…or train there for 25 years.” Unfortunately, the majority of runners participating in high altitude ultramarathons don’t fall into either category. In this piece, I attempt to summarize some of the existing information and relate it to our sport in the hopes of arming the altitude-disadvantaged athlete with some basic knowledge to be better prepared for events at elevation. Keep in mind that the majority of scientific studies published on altitude and its effects have focused on and benefited athletes preparing for national, world, and Olympic events from the marathon on down. Though a lot of anecdotal evidence is out there, very little research has been done in the way of clarifying how it specifically impacts the ultrarunner.
The sea-level dwelling athlete’s first reaction to high altitude running is best described like this, “I feel like I have a sock in my mouth, a vise on my head, and I’m running in wet cement.” It’s an awful feeling. Why does our effort increase and performance decrease when we run at higher elevations?
The air around us provides the oxygen we need to run. We breathe this oxygen into our lungs, which is then transported into the blood stream, and is then carried by hemoglobin to the working muscles. Traveling up in altitude relinquishes gravity’s hold on the air around us and causes atmospheric pressure to drop. Though the percentage of oxygen remains the same, the lack of pressure keeping these molecules together lessens allowing oxygen (as well as other atmospheric gases) to disperse and affects oxygen’s rate of absorption through lung membranes. Though lung capacity remains the same at altitude, the shortage of oxygen and lower atmospheric pressure makes it impossible to get the same amount of oxygen to the muscles in each breath compared to being at sea level.
Simply put, at altitude we are suffering from hypoxia—when the working tissues of the body are deprived of adequate oxygen supply. This phenomenon triggers a cascade of physiological events.
Channeling the Incredible Hulk
Though we don’t actually turn green, many of us feel flu-like symptoms or hungover when initially presented with high altitude conditions. Like David Banner during a Hulk rage, we undergo significant internal changes.
Immediately upon exposure to higher altitude:
- Blood plasma, the “water” of our blood, levels decrease rapidly in order to increase the density of red blood cells and oxygen carrying hemoglobin being pumped through the circulatory system.
- Due to this initial drop in plasma, stroke volume (the amount of liquid pushed through the heart) decreases, and in turn heart rate increases to compensate.
- Breathing rates increase both at rest and during exercise to bring more oxygen into the lungs.
In roughly two weeks’ time:
- Plasma levels return to normal and oxygen uptake becomes efficient.
- Resting heart rates, depending on the individual, either remain high or return to that of their sea-level value.
- Maximal heart rate remains unchanged but is achieved at a much lower work rate than at sea level.
- Muscle mitochondria (the cell’s power producers) increase in size and number and there’s a greater reliance on fatty acids as the primary fuel source rather than glycogen during exercise.
- Kidneys increase their output of the hormone erythropoietin (EPO) that stimulates bone marrow to increase red blood cell and hemoglobin production.
Who is Affected by Altitude When Running?
Both scientific studies and anecdotal evidence support the fact that running and racing at altitude is difficult for all athletes, no matter their level of fitness.
In a widely referenced 1982 study, Squires and Buskirk found a predictable reduction in VO2 max of approximately 8% for every 1,000 meters (3,280’) above 700 meters (~2,300’). Remember, from the previous speed-based workout column, that VO2 max refers to the maximum amount of oxygen an individual can use during intense exercise. The more oxygen one can utilize during hard bouts of exercise, the higher their VO2 max, and the more power produced during a workout. Naturally, if there is less oxygen (like at altitude) then VO2 max will suffer.
Jim Ryun, a former mile world-record holder, had to stop a quarter mile into his first run at 8,000’. His first mile time trial in Alamosa, Colorado, was 4:32, 37 seconds slower than his most recent mile at sea level
Ryan Hall, an accomplished 2:04:55 marathoner, describes altitude running like this, “Running at altitude is hard. Don’t feel like you are experiencing anything different from anyone else when you find yourself out of breath at the top of stairs or taste blood after a hard workout because we all feel it.”
Because the effects are so real, a number of institutions, including the NCAA and USATF, make allowances for race results at altitude. When attempting to qualify for a 10K championship race, for example, in Boone, NC (3,300’), collegiate men receive a 30 second adjustment; in Boulder, CO (5,200’), the allowance is 64 seconds; 10,000 meters on Northern Arizona University’s track in Flagstaff, AZ, (6,900’) is given a 99 second improvement; and while in Gunnison, CO (7,700’), runners lop off two full minutes from their posted time.
Preparing for Running Altitude
Though the side effects of altitude are inevitable and unavoidable, there are several things we can do to ready our minds and bodies for the experience. Because of the wide-ranging reactions individuals undergo at altitude there are both debatable and accepted training techniques.
1) Accepted. If a sea-level trained athlete travels to a race at elevations above what she is used to, the best course of action is to compete immediately upon arrival. If more time were available, a stint at the competition’s location of three to four weeks, the point at which most physiological adaptations have reached stasis, would be ideal. It is important to note that after the first 24 hours at high altitude dehydration and sleep disturbances can become more obvious, however, other negative effects (for example plasma density variations and increased breath and heart rate) will be noticeable even before the 24-hour window is reached.
2) Accepted. If you’ve just moved to altitude for a prolonged period of time, workout intensity should be reduced during the first two weeks while your body adjusts. Train no harder than your sea level easy run and long run training efforts for this brief period.
3) Accepted. Race and train at a slower pace. “On an easy and flat 8- to 10-mile run at 7,000 feet you can expect to move a full 20 to 30 seconds per mile slower than during the same distance at sea level. I suggest putting the GPS away and running by effort rather than by pace in the mountains,” says Flagstaff-based coach Greg McMillan. Running by feel is your best tactic while racing and training at altitude. Running too aggressively too often will lead to overtraining.
4) Accepted. Recovery while living and training at altitude, due to the lack of oxygen, is even more important than at sea level. Runners who don’t monitor their work output or eat properly can become anemic, experience muscle loss, and suffer from long bouts of muscle soreness and fatigue.
5) Accepted. In preparation for competition at altitude, focus on several weeks of VO2 max workouts at sea level to help prepare the body for the efforts you’ll experience. Here are two examples:
- Short Hill Repeats: The workouts will build leg strength and increase VO2 max. Find a hill with a medium slope (6% -10%) that takes between 45-90 seconds to ascend. Run up at an effort equivalent to your 5k race pace. Focus on good form with powerful push off and strong arm swing. Slowly jog down the hill to recover. Start with 4 to 6 repeats and build up to 12 to 14 reps.
- VO2 max intervals: These should last between one and six minutes with paces that emulate an 8- to 15-minute race. They’re tough so recover with a jog or walk that lasts the length of the fast repeat. Complete 6 to 30 minutes of VO2 max work during each workout depending on your experience and fitness level.
6) Accepted. Acute mountain sickness can be experienced as low as 6,000’, within the first six hours of exposure, and can last for up for as long as two days. Symptoms are headache, fatigue, dizziness, and sleep and stomach distress. Remedies include many natural remedies, proper hydration, retuning to lower elevation, supplemental oxygen, or medication containing acetazolamide (Diamox).
7) Debatable. Altitude simulation. Recent studies have shown that “real-world” altitude situations where both the oxygen content and the atmospheric pressure are low are more beneficial for acclimatization. Other studies have concluded that tools such as an altitude tent may have to be used for 16+ hours a day to yield benefits for the athlete. Altitude tents reduce the oxygen content in the air within them thus allowing the athlete to produce more red blood cells, but they cannot alter atmospheric pressure. Masks may increase lung capacity and power, but cannot modify pressure, oxygen content, or be worn all day.
8) Accepted. Meredith Terranova, an Austin-based sports nutritionist, explains why altitude training and racing increases fluid and nutrition requirements, “Due to an increased dependence of blood glucose as fuel, fatigue and low blood sugar levels occur more rapidly at altitude compared to sea level. Because the air at altitude is cold and dry, water and sodium (through sweat and respiration) are lost to the environment more quickly. In addition, at high altitude, food digestion efficiency declines as the body suppresses the digestive system in favor of cardiopulmonary functions like heart rate and stroke volume.”
Terranova, referencing an online Triathlete article by Pip Taylor, recommends that athletes training and living at high altitude follow these guidelines:
- Hydration. Extra fluid intake is essential. Higher altitude means that breathing is shallower and more frequent; this increased ventilation along with dry air leads to greater fluid losses through the respiratory system. Because sweat evaporates quickly, you can be led to believe that you are not losing much fluid and will be less inclined to drink.
- Fuel Utilization. Basal metabolic rate (BMR), the amount of energy used a rest or sleep, increases at altitude, especially in the first couple of days. Appetite is also suppressed by hypoxia. To minimize reduction in body mass and loss of muscle, take care to match your caloric needs. During acclimatization, BMR will slowly return to normal, but not quite to base level (sea level rate). There also seems to be a shift in fuel utilization toward a greater reliance on carbohydrate as opposed to fat stores. Upon reaching altitude, consider frequent small meals that are carbohydrate-rich to maintain energy levels.
- Iron Stress. Iron is required to manufacture hemoglobin (the oxygen-binding portion of red blood cells). As the body tries to adapt to the lower oxygen concentrations a greater number of red blood cells are produced. Before you go to altitude, consider having a blood test to ensure your iron stores are adequate. Talk to your doctor about considering the use of iron supplements and be sure to include iron-rich foods in your diet.
- Immune Stress. Altitude and hard training places a hard-hitting combination of stress on the body. A diet rich in natural antioxidants is important to help the body adjust and remain healthy with the demands you’ll be placing upon it.
Altitude Acclimation Strategies
- Live high, train high – You’ll be very good at training and racing at altitude. Expect to never achieve comparable sea-level training paces and race PRs while at altitude. Great for runners who gravitate towards high mountain courses, like Leadville, Hardrock, and Wasatch.
- Live high, train low – By training near sea level and living at elevation you gain the benefits of altitude without losing your racing fitness because you’ll be able to perform workouts at “real” VO2 max levels. However, there are not many locations that fit these parameters. Due to each individual’s reaction to the “high” component, the outcome of this strategy will vary significantly from one person to the next.
- Live low, train high – Though, physiologically, no gains are made, mentally you will be more prepared for the event as you’ll be familiar with the effects of high altitude on your body and how to pace yourself under those conditions.
- Live low, train low – The most common scenario. Use the suggestions in this piece to help you better prepare for your next event at high altitude.
Altitude is like a bee sting—people react to it differently. If your next race is in the mountains, on elevated plateaus, or high deserts, learn how your body responds in these conditions and take the best steps to ensure a successful race.
Call for Comments (from Bryon)
- Where have you run or raced at altitude. How did your body react?
- How have you prepared to run or race altitude? What seemed to work or not work well for you?
- Acclimatization To Altitude. Sports-Fitness-Advisor.com.
- Hall, Ryan. Altitude 101. Ryanhall.Competitor.com, July 12, 2010.
- Hebert, Dean. Altitude Training – Some Critical Facts. Coachdeanhebert.wordpress.com, Aug. 2, 2009.
- Hutchinson, Alex. A Reality Check for Altitude Tents and Houses. Sweatscience.com, Nov. 29, 2011.
- Little, Chelsea. Is Live High, Train Low Dead? Not a Chance, Says Stray-Gundersen-It’s Just Hard. Fasterskier.com, July 26, 2012.
- Lobby, Mackenzie. The Latest Research on Training and Racing at Altitude. Running Times Magazine.
- Martin, David E., Peter N. Coe, and David E. Martin. Better Training for Distance Runners. Champaign, IL: Human Kinetics, 1997.
- NCAA, comp. 2010 NCAA Championship Qualifying Time Altitude Adjustments. N.p.: NCAA.
- Noakes, Timothy. Lore of Running. Champaign, IL: Human Kinetics, 2003.
- Taylor, Pip. Keys To Proper Fueling When Training At Altitude. Triathlete.com, May 11, 2012.