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Altitude Training

Understanding Altitude & Acclimatization

What defines high altitude?

High altitude to a physiologist starts around 5000ft, the altitude where the body senses changes in the oxygen level and starts to respond by increasing breathing.

VO2max is the body's maximal ability to extract oxygen from the air and deliver it to the tissues. Above 5000 feet the maximum work a person can do decreases by 3% for every 1,000 feet. This means your body's ability to utilize oxygen diminishes with increasing altitude. Even after acclimatization, this only improves a little bit and a person can never perform as well at altitude as they can at sea level. With increasing altitude, you need to take more air into your lungs, contributing to the breathless feeling that many athletes experience when first coming to altitude, and especially if trying to perform at the same intensity as at sea level. One of the processes in acclimatization important for athletes is the production of a hormone called EPO or erythropoietin. This hormone acts on the bone marrow to produce more red blood cells. These cells carry oxygen from the lungs to the tissues. Increasing these cells effectively increases the 'oxygen carrying capacity' in your blood. However, this process takes weeks. EPO is a big topic among competitive endurance athletes.

What can you expect when you come to high altitude?

Physiological changes
Your body must adjust to the lower oxygen levels, and this process of adjustment is called acclimatization. Many changes occur in your body during acclimatization. One of the first things you will notice is that you breathe faster and deeper, to take in more oxygen. Therefore, you might feel short of breath for the first 2-3 days, especially with physical activity. Some shortness of breath with exercise is normal. Heart rate also increases, to supply more oxygenated blood to the tissues, and this might be noticeable the first few days; after that, it goes down towards a more normal rate. Increased urination is a response to changes in your body's acid/base balance and helps you in the acclimatization process; this is usually noticeable on the second day. Some people experience mild swelling in their hands, feet, and face, which is not serious.

Your body must adjust to the lower oxygen levels, and this process of adjustment is called acclimatization. Many changes occur in your body during acclimatization. One of the first things you will notice is that you breathe faster and deeper, to take in more oxygen. Therefore, you might feel short of breath for the first 2-3 days, especially with physical activity. Some shortness of breath with exercise is normal. Heart rate also increases, to supply more oxygenated blood to the tissues, and this might be noticeable the first few days; after that, it goes down towards a more normal rate. Increased urination is a response to changes in your body's acid/base balance and helps you in the acclimatization process; this is usually noticeable on the second day. Some people experience mild swelling in their hands, feet, and face, which is not serious.

Sleep Disturbances
Trouble sleeping is quite common at high altitude. The low oxygen directly affects the sleep center of the brain. Frequent awakenings, a light sleep and less total time of sleep are the main problems, and these usually improve with acclimatization after a few nights. Some persons, however, will have trouble sleeping despite acclimatization.

Competing at Altitude
For those athletes doing aerobic events over 5000 feet, 10-20 days of acclimatization at the performing altitude is ideal. Athletes participating in events over 12,000 feet must have acclimatization at an intermediate altitude prior to performance. Performing without acclimatization at this altitude could cause altitude sickness. Those participating in anaerobic sports (short intense events lasting less than 2 minutes, such as sprinting) at altitude do not require extended acclimatization, and may perform better because of lower air density.

Limitations
The response of erythropoietin to hypoxia is quite individual. While some have a significant response, others barely respond at all and may not have a benefit from sleeping and/or training at altitude.

While training at moderate altitude can be beneficial there are limitations. Athletic training above 8,000 feet is not generally recommended. At these higher altitudes, your exercise capacity decreases to the point that "deconditioning" can take place. Prolonged recovery time increases time required between training sessions. At even higher altitudes increasing catecholamines (epinephrine and norepinephrine), the body's stress hormones, contribute to weight loss and muscle wasting.

Other considerations of training at altitude
Nutrition becomes increasingly important when training even at moderate altitude. Rising stress hormone levels in response to lower oxygen levels place a higher demand for fuel on your body. As resting metabolism rates increase, athletes need to add to their caloric intake. Moderately increasing carbohydrate intake is key in replacing glycogen stores in your body after training and compensating for the increased caloric demand at altitude.

Hydration in the athlete is more important at altitude as well. Some athletes sweat 0.5 to 1.5 liters an hour. In addition, the lungs must humidify the air, which requires more water in the dry air at high altitude. To monitor hydration, a good rule of thumb for an athlete is to weigh themselves before and after training. Hydration to the pretraining weight will help athletes stay on top of their individual fluid needs.

Tips for preparation to compete at Altitudes

  • Start high altitude training 5-6 weeks before competition (3-4 weeks of high altitude training followed 15 days of sea level training)..
  • Train at altitudes between 2200 metres (7,217 feet) - 3,500 metres (11,482 feet) to negate the effects on training intensity and altitude sickness.

Tips for Running at Altitudes

  • To facilitate acclimatization arrive 5 to 10 days prior to your scheduled event.
  • Take your time
    • Begin your altitude training with low- to moderate-intensity running for the first five to seven days.
    • If the race is will be held at a higher altitude than you are used to, plan to run at the higher altitude for 5-6 weeks before the race for peak performance.
  • Nutrition & Hydration
    • Dehydration naturally occurs at higher altitudes
    • Drink at least three liters (12 or 13 cups) of fluids per day.
    • Increase your calorie intake by 300 calories to compensate for increased metabolism.
    • Take iron supplements to facilitate new red blood cell production.
    • Take vitamin C supplements to facilitate the absorption iron.
  • Race Conservatively
    • You will be pushed into your anaerobic zone much faster at altitude.
    • Start your race slower and build to race intensity over the first third.

Post-race Recovery

  • Readjust to low altitudes
    • Once you descend to a lower altitude, wait at least five to seven days before you try to race again.
    • The wait is needed to allow your body to reestablish blood-acidity and electrolyte levels.
  • Get plenty of rest
    • The increased breathing rate at higher altitudes often causes difficulty sleeping.
    • Take naps and avoid caffeine and alcohol.