Exploring sport online: Athletes and efficient hearts

# 6.5 Training at high altitude

Many of the world's best endurance athletes train at high altitudes – a long way above sea level – to improve their performance. At high altitudes there is less oxygen in the air and it's believed that the body has to work harder to extract what little oxygen remains. When the athlete returns to lower altitudes, their body retains the ability to use oxygen more efficiently and their performance will have improved.

## Activity 9: What you need to do

Think about the effects there might be from training at a high altitude, low oxygen environment. Look at the possible responses below and note down the ones that you think might be true.

Training at high altitudes:

- makes the heart stronger and more efficient
- makes the lungs stronger
- increases the number of red blood and/or white blood cells
- makes the muscles stronger.

## Discussion

We can use the knowledge we have gained in the previous sections to help us make a guess at what we might expect to happen.

- There is no reason to think that altitude training makes the heart stronger. As you've seen, the heart is a pump for the blood and the amount of oxygen in the blood will not affect it much.
- You might think that having less oxygen in the air means that the lungs have to work harder when breathing to get the oxygen that the body needs. This might appear to make the lungs stronger, in the same way that using your legs more makes them stronger.
- The amount of oxygen in the air does affect the blood. It increases the number of red blood cells (you'll remember these are the cells that carry oxygen around the body). This is the body's response to a lower amount of oxygen. It does not use the lungs to breathe more powerfully, but instead increases the blood's capacity to absorb the oxygen that is present. More red blood cells are made in order that the body absorbs more oxygen and gets the amount it needs. The advantage for sportspeople is felt when they return to sea-level: they have many more red-blood cells and so their body keeps this extra capacity to absorb oxygen. The extra oxygen helps them in endurance races, although the change is not permanent.
- We have not talked about muscles very much, but for now it helps to know that there is no evidence that it improves them – indeed, some researchers believe that altitude training actually reduces their effectiveness.

From the discussion, it appears that high altitude training has the potential to be beneficial. However, it is not as straightforward as it may seem. The effect of high-altitude training on blood is well known. But some coaches believe, however, that the overall effect of living at high altitude is not beneficial because the positive effect on the blood or the lungs is balanced by less beneficial bodily reactions such as a decrease in muscle strength. To get the benefits without the drawbacks, athletes can now train in altitude chambers, which are tents that have a reduced oxygen level, the kind of which you might expect at high altitudes. The athletes spend some of their time in the tent and some of the time outside. This affects their blood but allows them to train the rest of their bodies in an environment in which they are likely to compete.

Another way for an athlete to get the same advantage is for them to inject extra red blood cells into their own blood before a competition, or to use a drug that causes their own body to increase the number of red blood cells. This is illegal, and anti-doping authorities test carefully for this.

OpenLearn - Exploring sport online: Athletes and efficient hearts
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