Altitude camps: what the blood does and what it does not guarantee

The physiological argument

At altitude the pressure driving oxygen into the blood is reduced, and the body detects the resulting shortfall in delivery. One response is increased production of the hormone that stimulates the formation of red blood cells. More red cells mean more oxygen carried per unit of blood, which is directly relevant to endurance performance at sea level.

Other adaptations occur alongside this, including changes in the muscle's handling of oxygen and in buffering capacity. The overall logic is that a period at altitude produces a blood profile that pays off when the athlete returns lower down.

The problem with training high

Absolute training intensity falls at altitude, because the oxygen available to support hard work is reduced. An athlete spending weeks at altitude therefore trains slower than they would at sea level for the same effort. This creates a trade between the adaptation being sought and the quality of the training being sacrificed to obtain it.

The response has been approaches that separate where an athlete lives from where they train. Living at altitude while descending to train allows the exposure to continue while intensity is preserved. Simulated environments achieve something similar by reducing oxygen in a sleeping space rather than moving the athlete anywhere.

Timing the return

The adaptations gained at altitude are transient, and several of them begin to fade once the athlete descends. Some athletes also experience a period shortly after descent where performance is temporarily worse rather than better. The result is a window in which the benefit is thought to be greatest, and its timing is debated and individual.

This is why altitude camps are scheduled relative to a specific competition rather than used continuously. Getting that timing wrong can leave an athlete arriving at their event during the least favourable part of the response.

Why the response varies so much

Individual variation in how strongly the hormonal response is triggered is substantial and is not well predicted in advance. Some athletes show a marked increase in red cell production and others show very little from the same exposure. Iron status affects the ability to produce red cells, which is one reason it is monitored in this context by clinicians.

Sleep is frequently disrupted at altitude, which can offset gains through reduced recovery quality. Illness is also more common during camps, partly through the stress involved and partly through travel and group living.

The line with anti-doping

Altitude exposure and simulated altitude environments are permitted, while pharmacological manipulation of red cell production is prohibited. The distinction rests on the method used rather than on the physiological outcome being sought.

This has been argued about at length and the rules as they stand are clear regardless of the philosophical debate. Athletes remain responsible for anything they use, which is why any intervention is discussed with their medical team first.

What a camp is actually worth

The measured effects on performance are modest and are difficult to separate from the effects of a focused training block. Camps also provide uninterrupted training time, a controlled environment and freedom from ordinary distraction.

Some of the observed benefit may come from those factors rather than from the elevation itself. This is not an argument against altitude camps so much as an argument for honesty about what is producing the result.