When it comes to understanding the physiology of cold and heat exposure in sports, it's important to recognize the body's remarkable ability to adapt to environmental stress. In cold exposure, the body undergoes vasoconstriction to conserve heat and shivering to generate additional warmth. Over time, athletes who regularly train in cold conditions may experience an increase in brown adipose tissue, which enhances their ability to generate heat without shivering.

Conversely, in heat exposure, the body relies on mechanisms such as vasodilation and sweating to dissipate heat and maintain a stable core temperature. Athletes who acclimatize to heat stress may experience an expansion of plasma volume, improved sweat rate, and a decreased heart rate, all of which contribute to better performance in hot conditions.

For example, endurance athletes competing in cold environments, such as cross-country skiers, often develop specific physiological adaptations to excel in low-temperature conditions. Similarly, athletes preparing for events in hot climates, like marathon runners in tropical regions, undergo heat acclimatization to enhance their performance and reduce the risk of heat-related illnesses.

References:

• Castellani, J. W., Young, A. J., Ducharme, M. B., Giesbrecht, G. G., & Glickman, E. (2006). American College of Sports Medicine position stand: prevention of cold injuries during exercise. Medicine and science in sports and exercise, 38(11), 2012-2029.
• Périard, J. D., Racinais, S., & Sawka, M. N. (2015). Adaptations and mechanisms of human heat acclimation: Applications for competitive athletes and sports. Scandinavian journal of medicine & science in sports, 25(S1), 20-38.