Playing at Altitude
The higher you go in the atmosphere, the thinner the air. Thinner air means less oxygen, which makes it difficult to train intensely, and you may also suffer from acute mountain sickness (AMS).
Acute mountain sickness (AMS) effects can vary widely in the general population, and the severity depends on the elevation, the rate at which you reach the new, higher elevation, and your individual susceptibility.
The symptoms--headaches, loss of appetite, sleeplessness, and feeling sick--usually last only a few days at altitudes of around 3000 m; but at higher altitudes they can be severe enough or last long enough to interfere with training.
In addition, high air is extremely dry because water content in the atmosphere decreases with altitude. Furthermore, you breathe through your mouth in an effort to get enough oxygen, thus increasing water loss and losing the heat-conserving mechanism of the nose.
Exercising and competing at higher altitudes can have enormous performance consequences. Some of the immediate physiological effects of exposure to altitude are, increased breathing rate, increased heart rate and decrease in VO2max (maximal oxygen consumption).
The total effect of these adjustments is a reduction of work capacity. The higher the altitude, the greater the reduction. Performance at altitude is impaired in sports where aerobic power and where recovery that uses the aerobic system is important.
The Body’s Adaptive Changes
When your body is subjected to a low oxygen (hypoxic) environment, adaptive processes attempt to facilitate the intake, transport, and utilization of oxygen. This is believed to occur through an increase in the number of red blood cells, which are produced in response to greater release of the hormone erythropoietin (EPO) by the kidneys.
The higher the altitude, the greater the stimulus to produce extra red cells. Red cells carry oxygen from your lungs to your muscles. More red cells means your blood can carry more oxygen, which partly makes up for the shortage of oxygen in the air. So to compete at altitude, you should live at altitude for several weeks before the event.
Practical Implications for Players
1. Arrive as early as possible before competition to give your body time to adapt to the conditions.
2. Diet - A high carbohydrate, low salt diet allows for better adaptation and less risk of AMS. Some people experience significant decline in appetite and the resulting loss of muscle mass may hinder performance. Iron is used to make haemoglobin and the demand for making more red blood cells may require iron supplementation -- especially in women and vegetarians.
3. Fluids - Because mountain air is cool and dry you can lose a lot of water so be sure to maintain adequate hydration.
4. Adjust slowly – Do light exercise only on the first few days.
5. Alcohol - It is best to avoid alcohol consumption during the acclimatization period since it appears to increase the risk of AMS.
Training and Altitude
But what about when you come back to sea level? Will the extra blood cells supercharge your muscles with oxygen and push you along faster than ever? That's what should happen, but there are problems.
When you first move to altitude, the shortage of oxygen makes it difficult to train intensely, and you may also suffer from altitude sickness. If you don't adapt well to altitude, you may overtrain or lose muscle mass.
Even if you do adapt well, you still can't train with the same intensity as at sea level. The result? You detrain. When you come back down to sea level, you may do better or worse than before, depending on the balance between adaptation and detraining.
A potential solution to this problem is to live high, train low. There aren't many places in the world where you can live high and train low, so many athletes use methods to gain the train-low effect without coming down the mountain, or to get the live-high effect without living on a mountain.
Live High, Train Low
The research consensus is that living high and training low enhances any competitive performance that is limited by the ability of the athlete to consume oxygen. That means high-intensity events, lasting between a minute or two and several hours (such as tennis) will benefit from the live high, train low strategy.
The average athlete could expect an enhancement of aerobic performance of a few percent (2-3%) from living high and training low, but some athletes may get a bigger boost, while others may get no benefit at all.
It is highly impractical for many athletes to live at altitude and come down to train. Therefore, many athletes use methods designed to mimic the effects of the live high, train low strategy. These methods include:
Stay High and Train Hard with Oxygen
If the mountain does not offer the possibility of training low, an athlete may be able to do high intensity training on a sport-specific ergometer while they breathe oxygen-enriched air through a facemask.
Rest and Sleep in a Nitrogen Tent
Altitudes of around 2500 m can be simulated by reducing the oxygen content from the normal 21% to around 15%. A nitrogen house can be sited almost anywhere as a fixed or mobile facility.
A mini version of a nitrogen house, in the form of a tent, can simulate altitudes of up to 2700 m (9000 ft) and can be modified to simulate up to 4000 m (14,000 ft). The tent is set up on a bed or on the floor. The advantages are substantial: it is truly portable; it can be used with little or no disruption of family life, study, or work; and it is easily the best way to establish the altitude and program of exposure that suits the individual.
The units are expensive (US$5,500), but not dissimilar to the cost of a trip to a mountain and similar in price to other equipment used by top athletes.
Enhancement of the oxygen-carrying capacity of blood (by increasing the number of red blood cells) is a well-know means of increasing aerobic capacity. While this is essentially what happens naturally when living at altitude, there also exist ‘artificial’ means of doing the same thing.
Known as blood doping, injections of erythropoietin or blood transfusions also increase the red blood-cell mass that normally accompanies altitude exposure. With excessive use, both strategies are dangerous: the blood becomes thicker, and so increases the risk of sudden death from blood clotting.
It is not a surprise therefore, that blood doping is prohibited by the World Anti-Doping Agency, and so also under the Tennis Anti-Doping Programme.
There are two good reasons for banning a practice that enhances performance: either it causes illness or injury, or it gives the athlete a technological advantage that is too expensive or too new for most other competitors to use.
Living on a mountain with frequent trips down to the valley is unlikely to be considered unsporting. But aside from the temporary altitude sickness, altitude exposure can be damaging to health in a small proportion of the population.
Continuous exposure to altitude may lead to accumulation of fluid (edema) in the lungs and brain, which can be fatal. Furthermore, excessive production of red blood cells increases the risk of sudden death through blood clotting or a heart attack. However, the average athlete who spends a few weeks at a moderate altitude will not have these problems.
Altitude chambers, nitrogen houses and nitrogen tents would be dangerous if the simulated altitude was high enough and long enough to raise the thickness of blood to an unsafe level. However, so far these devices are legal.
Furthermore, these devices are unlikely to be banned as an expensive innovation, since they are no more expensive than high-tech training equipment used by many athletes. Can they be banned?
Possibly not, because you can't ban normal altitude training, so it may be seen as unfair to ban a safe practice that makes it easier or cheaper for athletes to achieve the same effect. Still, it will be a sad day when athletes have to spend weeks of their lives in such apparatus to keep up with other competitors.