Recently, several national football teams spent some time at altitude on the Austrian Alps in preparation for the World Cup. Athletes from a number of endurance disciplines use altitude training as part of their yearly training program. However, scientific evidence is not clear at all as to whether altitude training is beneficial for human performance or otherwise.
A recent study I did with Peter Robbins (also University of Oxford) and others (citation below) shows substantial evidence supporting the hypothesis that prolonged exposure to low oxygen could in fact be detrimental for physical performance. The findings are published in the Proceeding of the National Academy of Sciences.
Oxygen is limited high up on the mountains, so our body needs to find ways to obtain the oxygen necessary for survival (e.g. we breathe harder and our heart pumps more blood). In our body the levels of a protein called hypoxia-inducible factor, which is stimulated by low oxygen, increase and play a central role in our response; for example, this protein stimulates erythropoietin (EPO), a hormone that controls/increases the production of the oxygen-carrying red blood cells. Upon return from altitude to sea level the number of red blood cells remains temporarily high and could enhance our capacity to perform long and strenuous (aerobic) physical activity. However, at altitude our body also changes the way in which it uses up energy, shifting to a less energy efficient mechanism.
This change is counterproductive for physical performance: its magnitude can overcome the
positive effect of the elevated number of red blood cells, and it can be disadvantageous for athletes.
Rare patients with a natural genetic mutation that chronically activates the hypoxia-inducible factor (high levels of this protein are present also at sea level in these patients) were recruited for the experiments. Patients’ exercise capacity and the way in which their muscles use up energy were investigated through a cycling exercise test to exhaustion and a light pedalling exercise (ankle plantar-flexion) in a magnetic resonance scanner. Results show that chronically elevated levels of hypoxia-inducible factor are associated with very limited exercise capacity, mostly determined by the use of less energy efficient mechanisms in the muscles.
With our study, we now understand physiological processes related to oxygen balance in the human body better. This is not only important for athletic performance: understanding these fundamental processes better may eventually lead to better medical care of conditions where oxygen supply in the body is limited.
Only a limited exposure to altitude can be beneficial for athletic performance, and future research
needs to quantify a “prescribed amount” of exposure to low oxygen. As long as this dosage is not clear, on the Alps athletes can only be sure to find some tasty apple strudel.
CITATION: Formenti F, Constantin-Teodosiu D, Emmanuel Y, Cheeseman J, Dorrington KL, Edwards LM, Humphreys SM, Lappin TRJ, McMullin MF, McNamara CJ, Mills W, Murphy JA, O’Connor D, Percy MJ, Ratcliffe PJ, Smith TG, Treacy M, Frayn KN, Greenhaff PL, Karpe F, Clarke K, Robbins PA (2010). Regulation of human metabolism by hypoxia-inducible factor (HIF). In press, Proceedings of the National Academy of Sciences. http://www.pnas.org
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