Cooling athletes before competition in the heat: comparison of techniques and practical considerations

With the general acceptance that high ambient temperature and humidity have a detrimental effect on performance, the topic of whole-body cooling and sport performance has received considerable attention from sport scientists, particularly in the lead up to the relatively hot Olympic games of 1996 in Atlanta, Georgia, USA, and 2004 in Athens, Greece. This trend is likely to continue as athletes begin to prepare for what will likely be another hot Olympic games in 2008 in Beijing, China. To overcome the reduced exercise capacity associated with the heat, a number of precooling methods have been utilised to cool the body prior to exercise, with the greatest benefits likely associated with prolonged endurance-type exercise. An increase in heat storage capacity following a precooling manoeuvre has been suggested as the primary means of delaying fatigue during endurance exercise performance in the heat; the notion being that the increased heat storage capacity will allow an athlete to complete a greater amount of work before a critical body temperature is reached. However, the specific underlying mechanisms responsible for delaying fatigue during exercise in hot ambient conditions remains unclear. While significant research in this area has been completed in the laboratory setting, few studies utilise performance protocols, and even less address the practical and logistical issues associated with precooling an athlete prior to elite competition in the field. This review addresses evidence supporting the use of a precooling manoeuvre prior to endurance exercise, the potential underlying mechanisms responsible for improved endurance performance following precooling, and the practical issues associated with the use of precooling prior to competition for elite athletes.