|Some of the running and biking trails|
|A view from the top of Alta and a view of Little Dell Reservoir at the top of Emigration Canyon|
Over the course of a few weeks, your body adapts to these low oxygen (or hypoxic) conditions in several ways. First, there is a shift in the hemoglobin molecule that allows for oxygen to be released to your muscles more easily. Second, your body increases the production of erythropoietin or EPO. This is a natural hormone (or not so natural if you are doping) that stimulates the bone marrow to produce more red blood cells, which means more hemoglobin is around to deliver oxygen to your muscles. By directly measuring EPO, red blood cell volume and hemoglobin mass, researchers can quantify how well individuals respond to altitude training.
Another change that happens at altitude is that you start breathing faster and your heart rate increases even at rest. When you breath faster, you exhale a lot of carbon dioxide (which exists in your blood as carbonic acid). As you breath off more and more carbon dioxide (think acid), you blood becomes more alkaline or basic. To restore proper acid-base balance of your blood, the kidneys adapt by excreting the excess base in the form of bicarbonate. This allows you to keep breathing at an increased rate without compromising the acid-base balance of your blood.
There may be other ways the body adapts to high altitudes including increased efficiency in the way muscle cells use oxygen to make ATP (the energy molecule that allows for muscle contraction). Some researchers have hypothesized that the mitochondria in muscle cells may adapt to make more ATP with less oxygen, there may be more blood vessel growth in muscles, and the muscles may develop a greater ability to buffer lactic acid or tolerate higher levels of lactic acid before fatiguing.
|A view from a trail run out to Lake Blanche|
When it comes to altitude training, there are 4 main methods that athletes use. These include:
1. Live high-train high
Basically, athletes who train using this method spend all their time at altitude. In one study of 39 collegiate runners, researchers found that living high and training high for 4 weeks increased VO2 max by 5% from baseline, but there was no improvement in 5000m running performance. The one drawback to this training plan is that being at altitude reduces your VO2 max, which means that peak running or biking speeds will be lower than at sea level, and you will not be able to train at the same absolute intensity.
2. Live high-train low
Athletes who use this method of training get the physiologic benefits of being at altitude, but train at sea level so that training intensity and VO2 max is not compromised. Interestingly, in that same study of collegiate runners, those who lived high and trained at sea level increased their VO2 max by 5% AND improved 5000m running performance by 13.4 seconds. However, in a recent placebo-controlled double blinded study of 16 endurance cyclists, authors found that after 4 weeks of living at altitude for 16h/day (athletes lived in hypoxic rooms at a Nordic skiing center in France to simulate being at an altitude of 3000m) and training outside at an altitude of about 1,000m did not improve hemoglobin mass, VO2 max or power output in a 26km time trial test. One thought is that these cyclists already had high red blood cell counts from years of training and thus, this method of altitude training may increase performance of lower-end athletes, but the same benefits may not be seen in the already elite.
3. Live low-train high and 4. Intermittent hypoxia at rest (repeatedly switch between breathing severely hypoxic air that simulates being at an altitude of 4500-6000m and normal air for short durations of time)
There is no evidence to support either of these methods of altitude training, so there's not much more to say here.
|A view from a trail run up Mount Wire|
If interested, here are the articles I used for this post:
- Lundby et al. Does ‘altitude training’ increase exercise performance in elite athletes? Br J Sports Med 2012; 46: 792–795.
- Fudge et al. Altitude training for elite endurance performance: A 2012 update. Current Sports Medicine Reports 2012; 11(3): 148-54.
- Levine et al. “Living high-training low”: effect of moderate-altitude acclimatization with low-altitude training on performance.
- “Live high–train low” using normobaric hypoxia: a double-blinded, placebo-controlled study.