Exercise, Performace & Altitude

Recently, there has been a lot of attention for the controversy of altitude training. Does it work? What are the effects of altitude training? Why do some people think altitude training is crucial, whereas others don’t?

Performing physical activity at altitude might be more difficult than at sea level. At height, your VO2max and lactate threshold decrease when compared to lower heights. As these physical characteristics are important for the athletic performance, it won’t be a surprise that competing at altitude will be quite different from competing at sea level.

Altitude effects

One of the effects of being on a high altitude is that there is less oxygen in the air, resulting in a low oxygen pressure (PO2). Therefore, you’ll need to inhale more air in order to keep the oxygen pressure in your body at the same level. Because of this, you will probably experience some kind of hyperventilation. Due to this hyperventilation, you will exhale a lot of air as well, which results in a decrease of the CO2 pressure in the body (PCO2).

In addition to losing CO2, the body also loses a lot of water when exhaling. On top of this, the sweat rate will increase due to a lower humidity of the air on greater heights. Besides the drop in PCO2, dehydration might therefore be another important effect at altitude.

Acute exposure to altitude might even be dangerous! Altitude sickness can be very severe and may even be fatal. Always climb gradually and when you are not feeling well, stop climbing altogether and descend (gradually!).

The consequences

The drop in PCO2 and dehydration have major consequences for the body and your (athletic) performance. Due to the CO2 loss, the blood becomes less acid and thus more alkaline (an increase in pH). To counteract this – the body wants to maintain a steady state (called homeostasis) – the kidneys will excrete more bicarbonate. As discussed in another blog, this bicarbonate is very important during exercise. Bicarbonate is a buffer against acidification. When you are exercising at a higher intensity, some of the produced acid will be buffered by this bicarbonate and your will be able to continue at that exercise intensity somewhat longer. But when it’s not there anymore, the body won’t be able to buffer the excess acid and your exercise performance is likely to suffer. No need to say that this has something to do with the impact on the lactate threshold and anaerobic capacity.

Additional physical adaptations to height are an increase in heart rate and a decrease in stroke volume of the heart. Probably several factors contribute to these adaptations. When you lose to much water and get dehydrated, your blood volume will decrease. Therefore, your heart needs to pump more to get the same amount of blood to the working muscles.


After several days the acute effects of the altitude will slowly fade away. The hyperventilation will become less and the resting and exercise ventilatory volumes will decline. Also, the PCO2 of the body will be restored (to some extend), resulting in an increase of the bicarbonate buffering capacity.

Another gradual adaptation to altitude is the increase in red blood cell count. Due to the lower oxygen pressure in the liver and kidneys, the body will get the signal to produce more red blood cells. But if the lowered oxygen pressure is an acute response to altitude, then why is the extra red blood cell production a gradual adaptation?

Red blood cell production isn’t the problem in this. The body will produce the red blood cells as soon as it gets the signal to do so. However, red blood cells have to mature before they will be ready to go. A red blood cell needs to mature for a minimum of 6 days. This is why an increase in re blood cell count will be visible after approximately 10 days. Eventually, the increase in red blood cell count and the restored bicarbonate buffering capacity will lead to an improved, or restored VO2max. The levels won’t however be the same as sea levels.

So, when you have a competition at altitude, make sure you arrive at least 10 days before the day of the competition. This way your body can get used to the circumstances and adapt gradually. If necessary, you should gradually increase altitude. In order to prepare the body optimally, start training on your second day at altitude. At first, reduce the training volume.

Altitude training

But what is the effect of the altitude training when you have to perform at sea level? Does the increased red blood cell count help you to perform better at sea level?

There are several altitude training protocols that are often being used:

  • Live high, train high
  • Live low, train high
  • Live high, train low

Some studies demonstrated positive results for each of these protocols. However, others found no improvements or only very small improvements. Hence the controversy.

As described in a previous blog: the effects of an altitude training seem to be highly individual! For some people it might help, for others it won’t.

Want to know your own VO2max or Lactate Threshold? Or do you need help with your training? Let us know via cycling@science2move.nl or have a look at https://de-vitaliteitspraktijk.nl/inspanningstesten/conditietest/.

Macdougall D, Sale D. The Physiology of Training for High Performance. Oxford: Oxford University Press; 2017.