The hot and humid environment of Rio de Janeiro was a big challenge for all the athletes participating in the past Olympic Games. It is well known that heat can impair performance, because of the early onset of hyperthermia and dehydration, which are two of the main determinants of fatigue. There are two strategies to minimize this heat-related performance impairments: the first is to perform heat acclimatization during the training phase, the latter is to contrast hyperthermia onset both before and during performances.
How does the body adapt to heat? And how could athletes optimize heat acclimatization?
It is well documented that training in hot environments produces some positive physiological adaptions, such as an increase in sweat rate, a reduction in sweat sodium content and an increase in plasma volume. These adaptations lead to an improved exercise tolerance in the heat. To get these beneficial effects it is necessary to experience heat exposure during training sessions, which produce an increase in body core temperature. To do this, athletes should perform their low-intensity training sessions (e.g. training intensity corresponding to 60% of their VO2max) in hot environments (e.g. during the hottest hours of the day or in a hot environmental chamber), however it is important that performing high-intensity sessions in a moderate or low-temperature environment is continued, in order to not reduce the sustainable intensity. In literature it is reported that training for an hour in hot environment for 7 to 10 days at moderate intensity is effective in producing accurate heat acclimatization.
How could athletes contrast heat-related performance reduction immediately before and during the race? Athletes could rely on some “pre-cooling” strategies, in order to allow the warming up process of the exercising muscles while keeping the body/core temperature low. Following this, athletes could undergo water immersion before the warm-up or alternatively wear a cooling ice vest during the warm-up phase.
During performances and activities, it is fundamental to maintain hydration levels, dehydration accelerates the hyperthermia onset therefore it is essential to be avoided. Drinking a sports drink which also contains electrolytes (sodium, potassium, magnesium) could be the optimal choice. It is recommended to not exceed 1.2 liters per hour of liquid intake during activity, because it would overcome the gastrointestinal absorption capacity, then possibly causing nausea, vomiting and/or diarrhea.