Denver and the Front Range areas are roughly 5000+ feet, or a mile (1600 meters) high. This elevation, while nothing extreme, definitely presents a challenge to visitors. That’s why we make our friends who come to visit, stay in Denver for a while before we take them up to where the fun really starts, and the hypoxia kicks in. The trails start at the base of the Rockies (5000 feet) and go all the way up to very top, at 14,000 feet. Yes, you can ride your bike (or run, ski, or snowshoe) to the very summits of Colorado’s highest peaks.
By definition, “official” altitude training takes place at elevations over 8000 feet (2500 meters). This is done to “trick” the body into producing more red blood cells. More blood cells mean more oxygen (and nutrients) are delivered to the working muscles. Think blood doping, but with great scenery and lots of hard work – that is legal as well.
A common misconception about altitude is that the air contains less oxygen. This isn't true. The concentration of oxygen at altitude (especially where most of us have relatively easy access – up to approximately 14,000 feet) is the same as sea level, about 20.9%. At altitude, the barometric pressure (air pressure) is less, making it more difficult for humans to inhale the air – giving the effect of a relative lack of oxygen.(1)
How it Works
Now that we have that out of the way, what is the point of altitude training?
When deprived of adequate amounts of oxygen, the body’s attempt to adapt leads to increased production and concentration of red blood cells and hemoglobin. Hemoglobin is a protein that carries oxygen on the red blood cells – think of hemoglobin as the seats, and red blood cells as a car that delivers oxygen throughout the body.
Upon returning from a stint at altitude, the athlete that returns to a lower elevation will benefit from a higher red blood cell concentration. More red blood cells allow more oxygen to be delivered to working muscles. More oxygen leads to an increased ability to do work, leading to increases in endurance, speed, strength and recovery. This is why everyone likes to train in Boulder, Colorado. (Although we think Fort Collins is a much cooler place…with the same altitude, but less attitude!)
Oxygen delivery is one of the main performance limiting factors – the measurement of Max Vo2 is a measure of how much oxygen the cells of the body are able to use during exercise. (You can think of this as a measurement of how efficient your body is.)
A higher Vo2 typically translates into higher performance. As a side note, some of the highest recorded Vo2's were from Lance Armstrong and the running legend from Oregon, Steve Prefontaine - both had measured Vo2’s at 84 ml/kg/minute. And that is A LOT, my friends. The ‘typical’ male measures around 40 ml/kg/min and the ‘typical’ female is about 35 ml/kg/min. This of course varies widely among people.
The hormone erythropoietin (EPO) is responsible for increasing red blood cell production in the body. High-altitude training causes the body (actually the kidneys) to naturally increase EPO at safe levels that it can withstand.
Blood doping also involves EPO, but this is performed by injecting a synthetic form of EPO, which boosts red cell levels sky high. Blood doping is of course illegal in athletic competition, and has some nasty side effects like stroke, heart failure, and death. Needless to say, we strongly discourage this. We do however strongly encourage you to do some altitude training, as there is always plenty of great scenery, and adrenaline!
Note: if you do plan on incorporating high altitude training, make sure you get tested for anemia, and for a storage form of iron known as ferritin. A lack of iron will make your efforts at altitude training (or any training for that matter), all for naught. Iron is crucial for red blood cell development, and you will feel super crappy if you are anemic and head to the mountains. Not good.
Critics of altitude training argue that the gains of training at altitude are negated by the limited ability to train at high intensity at lofty elevations. In other words, the relative lack of oxygen and its resulting decreased ability to perform can lead to detraining via reduced training intensity.
Also, acclimatization to heat is lost while training in the typically cool high altitude temperatures. Regardless of fitness, performance at altitude is severely limited. However, performance will never match that at sea level – one reason why no world records (running anyway…) have been set at altitude.
Another issue is altitude sickness, a condition that can affect anyone traveling above 5000 feet for as little as a few hours and can vary from feelings of a mild hangover to severe illness necessitating emergency care.
Live High, Train Low
An ideal mantra for altitude training is “live high, train low”.
Living at altitude allows the body to adapt and at the same time not punishing it by training intensely in a relative lack of oxygen. Proponents suggest that altitude training be performed at low and moderate intensity, and high intensity workouts only be performed at lower elevations.
This model has proven benefits (increased Vo2 and red blood cell concentrations), but presents a logistical problem in finding that perfect piece of real estate and career that allow one to “live high and train low”.
At one point, certain training outfits were building, and housing their athletes in ‘altitude houses’’, which were specially designed houses in which the oxygen inside is maintained at 15% oxygen, thereby mimicking the effects of altitude. Athletes would live there “at altitude” and once he enters the outside world, they're at low altitude again.
There are even specialized tent-like sleeping chambers that also mimic high altitude.
High-altitude training is much like medicine, in that its results depend on the dose taken and its effects will eventually wear off.
Too low of an altitude will not create the wanted benefits, while too high of an altitude will lead to more problems with adaptation (such as altitude sickness) that will negate any possible benefits. For the typical marathon runner looking to incorporate altitude training, research has shown the greatest benefit from living at an elevation of 6500 – 8200 feet, for a minimum of 20 hours a day for 4 weeks. This average runner who follows this plan can expect an improvement of 8.5 minutes (~5%) over the length of a marathon.(2)
How Long Does It Last?
The majority of studies have only looked 3 weeks from the time when an athlete discontinues altitude training. The average lifespan of a red blood cell is approximately 90 days, or 3 months. There is some evidence that in athletes who train intensely, the red cells may only last from 2 to 3 months(3).
Given that the benefits of high-altitude training are due to increases in red cells, we can expect the benefits to diminish as the body recycles the now unnecessary red cells (because the person is now at low altitude and the body is extremely efficient in ridding itself of what it considers ‘unnecessary’).
And in typical dose-response fashion, the benefits will decrease gradually over that 2-month time frame. Periodic return to altitude over these two months may act as a ‘booster’ to the benefits, but the exact quantity and time frame necessary for this effect are not currently known.
Common Altitude Training Problems
Acute Mountain Sickness (Altitude Sickness)
The body just doesn’t really like being starved of oxygen. When this occurs, altitude sickness happens. Signs include headache, fatigue, nausea, dizziness, shortness of breath, insomnia and high blood pressure. Sounds a bit like a bad hangover, doesn’t it? Well that is pretty much what it feels like, too.
Most cases of altitude sickness are benign, however it can become very severe with symptoms like impaired motor control and fluid in the lungs and brain. The more rapid the ascent to a greater altitude typically results in greater likelihood of more severe case. If you do go to altitude, hydration is the key.
Anemia & Blood Health
Anemia is a common blood disorder that mainly involves a lack of the mineral iron. Sometimes it can be from a lack of Folic acid or Vitamin B-12. You can read more about anemia here. We recommend proper blood testing to determine whether or not you have anemia.
Some people (especially athletes) are just prone to anemia, or worse suffer from ‘sub-clinical’ anemia where they aren’t exactly diagnosed with anemia, but they suffer from the effects. An iron supplement is a good idea to prevent the fall into anemia – which can take months to recover from (as well as your performance!).
Perhaps the biggest challenge to athletes at altitude is just acclimatizing, or getting used to the relative lack of oxygen and dry air. The most often recommended tips include staying hydrated (drink ½ of your body weight in ounces of water each day), avoiding alcohol, and keeping blood sugar elevated. Lack of appetite is common at altitude; the same nutrition rules apply here as well as in the flatlands. However, even the most diligent athletes will still feel the effects of altitude; the following can take the last remaining edge off.
Homeopathic Cocoa has been studied on Mount Everest and significantly increased oxygen saturation in climbers who took it. (4)
Gingko biloba is a popular botanical medicine. Taken before ascending to altitude, it can lessen the severity of altitude sickness symptoms. (5,6,7)
Rhodiola is an extremely helpful botanical medicine for all athletes. It aids performance at altitude by helping the body to adapt in stressful conditions through a number of mechanisms. (8,9,)
1. West, J. Prediction of barometric pressures at high altitudes with the use of model atmosphere. J Appl Physiol. 1996; 81: 1850-1854).
2. Chapman R, Levine BD. Altitude training for the marathon. Sports Med. 2007;37(4-5):392-5.
3. Szygula, Z. Erythrocytic system under the influence of physical exercise and training. Sports Medicine. 1990;10(181-97).
4. Shackelton MF, et al. The Effect of Homeopathic Coca on High Altitude Mountain Sickness: Mt. Everest Base Camp. Complementary Health Practice Review, Vol. 6, No. 1, 45-55 (2000)
5. Gertsch JH, et al. Ginkgo biloba for the prevention of severe acute mountain sickness (AMS) starting one day before rapid ascent. High Alt Med Biol. 2002 Spring;3(1):29-37.
6. Moraga FA, Flores A, Serra J, et al. Ginkgo biloba decreases acute mountain sickness in people ascending to high altitude at Ollague (3696 m) in Northern Chile. Wilderness Environ Med. 2007;18:251-257.
7. Roncin JP, Schwartz F, D'Arbigny P. EGb 761 in control of acute mountain sickness and vascular reactivity to cold exposure. Aviat Space Environ Med. 1996;67:445-452.
8. DeBock K et al. Acute Rhodiola rosea intake can improve endurance exercise performance. Int J Sport Nutr Exerc Metab. 2004 Jun;14(3):298-307
9. Abidov M. et al. Effect of extracts from Rhodiola rosea and Rhodiola crenulata (Crassulaceae) roots on ATP content in mitochondria of skeletal muscles. Bull Exp Biol Med. 2003 Dec;136(6):585-7.