Could altitude training benefit team-sport athletes?

INTRODUCTION Following the dominance of altitude acclimatised athletes during the 1968 Olympic Games held in Mexico City (2400 m), and early anecdotal training experiments in the USA in the 1970s, altitude (hypoxic) training has become very popular among individual endurance athletes including marathon runners, cyclists, swimmers and triathletes. Altitude training is used to further enhance exercise performance at sea level or to acclimatise to competition at altitude. The fundamental theory behind altitude training is simple; that is, by exposing an athlete to an environment that is low in oxygen, the body will eventually adapt to this stress and improve its efficiency at transporting and using oxygen. However, this may not be the only factor involved in the enhancement of performance since other central (eg, ventilation, haemodynamics or neural adaptations) and/or peripheral (eg, muscle-buffering capacity or economy) factors may also play an important role. There are many different altitude training strategies. ‘Live high-train high’, as do the East African runners who live and train at altitude. ‘Live high-train low’ invokes the beneficial effects of altitude while avoiding, first, the need for a decrease in training intensity and, second, the detrimental effects of chronic hypoxia. Altitude training in the form of ‘live high-train low’ was first demonstrated to improve athletic performance in the late 1990s. Since then, research into altitude training and its adaptive mechanisms has gained popularity, possibly because it offers performance benefits to athletes in the range 1–3%. Other approaches also include intermittent hypoxic exposure at rest or during continuous training sessions, interval-training sessions and even ‘live high-train low and high’ or ‘live high-train low in the heat’. Until now, however, reports of performance improvement vary widely, and the efficiency of some of the abovelisted methods has not been thoroughly investigated.