Notes on Randall Wilber's "Altitude Training and Athletic Performance"
John's comments in italic
Part I: Potential physiological benefits
Effects of altitude on training:
Upon exposure to altitude, the body makes several adjustments.
*Cardiac output and stroke volume, both in submaximal and maximal exercise, drops.
*Ventilation, that is, the total flow of air in and out of the lungs, increases.
*This increase in ventilation, coupled with hormonal changes causing an increase in urination, gives rise to a great increase in the body's demand for water. Fluid intake at altitude, especially during the acclimatization period, should be as much as 4-5 L per day.
*Lactate buffering is impaired during adaptation to altitude because the increase in CO2 exhalation disrupts the equilibrium of the bicarbonate buffering system, allowing H+ to accumulate faster.
*In men, carbohydrate utilization increases; that is, a larger proportion of the athlete's daily energy comes from carbohydrates. Women maintain a similar level of carbohydrate and fat utilization vs. sea level. Both genders will likely need to increase their caloric intake, but men in particular must consume extra carbohydrates. High-glycemic food ought to be consumed immediately after exercise at altitude.
*The body demands more iron to produce red blood cells. Unsuplemented, the ferritin levels of lowland athletes training at altitude often drops significantly. Furthermore, athletes who are iron-deficient upon ascent (defined in one study as men with <30 ng/ml ferritin and women with <20 ng/ml) respond very poorly to altitude. Therefore, iron supplements are a necessity. Not only solid iron sulfate, but so-called "liquid iron" might be a good idea too. One study prescribes 5-45 ml/day of a 9mg/ml liquid iron solution, depending on ferritin levels.
*The increase in oxygen demand, coupled with increased training at altitude, results in an increase of cortisol, a stress hormone. Cortisol can impair training and depress the immune system, making athletes more susceptible to illness. It can also cause muscle catabolysis, where the body "eats" its own skeletal muscles. This muscle catabolysis may be able to be counteracted by consuming protein after exercise and before bed
*Oxidative stress increases, possibly because of the increased oxygen consumption, increased UV exposure, and free radical production. Oxidative damage can result in fatigue, DOMS, and injury. Wilber suggests supplementation with 400mg of vitamin E per day to counteract oxidative damage. Wilber also mentions sunblock, sunglasses, vitamin A, and vitamin C. Other (and more natural) antioxidant sources, such as tea, pomegranate juice, blueberries, and grape juice, will likely also go a long ways towards protecting the body.
*Under proper diet and hydration, body composition should not drastically change.
Performance is hampered at altitude for a few reasons:
*Reduced partial pressure of oxygen: Arterial oxygen delivery works by diffusion. O2 diffuses from the air into the blood, then from the blood into the muscles. This diffusion is governed by a difference in partial pressure. Hence, with a lower ambient PO2, diffusion does not happen at as high of a rate, and the arterial blood saturation % drops.
*Decrease in maximal oxygen consumption: probably related to the reduction of PO2. Because blood passes through the lungs too quickly to be fully saturated, the maximum rate of oxygen consumption decreases vs. sea level conditions. This leads directly to a decrease in VO2 max.
*Decrease in training capacity: the lack of available oxygen necessitates a slower pace during intense intervals, which can lead to less quality in workouts.
*Sprint work, at least with full recovery, is not impaired at altitude, and is in fact aided by the decrease in air resistance.
Training response to altitude:
*The decreased arterial saturation of O2 stimulated the kidneys to produce erythropoietin (EPO), a hormone that stimulates red blood cell production.
*The lack of oxygen also stimulates an increase in the number of mitochondria and the enzymatic activity within them. Results are inconclusive on whether altitude stimulates changes in capillary beds or muscle composition.
Part II: Altitude Training and Athletic Performance
*results from many years of studies are inconclusive on whether altitude training improves sea-level performance in trained athletes. Problems result from poor methodology, lack of a control group at sea level, different training protocols, and small study numbers.
*In a retrospective investigation into "responders" and "non-responders," over 80% of "responders" (people who improved after altitude training) were in the "Live High, Train Low" training group. The rest were in the traditional "Live High, Train High" group.
*It is hypothesized that the ability to do maximal and near-maximal training at near sea level allows athletes to retain the training intensity of sea-level groups but reap the physiological benefits of altitude.
*Of studies supporting the benefits of the LHTH approach, the greatest benefits seem to be from groups training and living between 7,000 and 10,000 feet.
*Of studies not supporting the benefits of the LHTH approach, the only groups with statistically significant DECREASES in performance, VO2 max, and Hemoglobin levels lived and trained at over 13,000 feet. Therefore, we can conclude that, at the very least, you will not get WORSE by training and living at altitude in any city in the United States. Up to 10,000 feet seems to be a safe altitude.
*Recent well-designed studies by Levine and Stray-Gundersen suggest that 1) LHTL is superior to sea-level training for periods on the order of one month and 2) Base training at altitude and faster training at low altitude (so-called "Hi-Hi-Lo" training) is equally good From this, it seems obvious that the best choice would be HiHiLo training, because it would save on trips down from the mountains.
*One recent study asserts that athletes can be divided into "responders" and "non-responders" based on their blood EPO levels (% of sea level baseline: responders had a blood EPO increase of ~156% after 30h and nonresponders increased only ~137% of SL base) and total red cell volume (ml/kg) (total red cell volume increased in responders significantly (~3.0 ml/kg) and remained unchanged in nonresponders). The "responders" should improve greatly from altitude training. Possibility of testing this before and after altitude training? Blood EPO is measured in IU/ml
"After 14 days at altitude, Epo was still elevated in responders but was not significantly different from sea-level values in nonresponders"
"In conclusion, after a 28-day altitude training camp, a significant improvement in 5,000-m run performance is, in part, dependent on 1) living at a high enough altitude to achieve a large acute increase in Epo, sufficient to increase the total red cell volume and V ˙ O2max, and 2) training at a low enough altitude to maintain interval training velocity and O2 flux near sea-level values."
Most successful coaches and athletes recommend 7-10 days of acclimatization upon ascent to altitude before intense training begins. Programs differ during the "stress" phase, but it lasts from 2 to 6 weeks. Before return to sea level for competition, a week or so of backed-off training is recommended to absorb the hard training. This may not be necessary if hard workouts are done at low altitude.