UCI Sports Nutrition Project: Special Environments.

Elite cyclists frequently train and compete in extreme environments, such as heat, and cold conditions that are becoming more common due to climate change. Altitude training, aimed at preparing athletes for high-altitude events, is widely employed to enhance subsequent sea-level performance. Similarly, heat training has proven to have a similar transfer effect, in addition to the essential acclimatization effects, relevant for performance in hot conditions. Exposure to these challenging environments increases physiological stress raising energy and carbohydrate oxidation rates, and affecting overall performance. This Union Cycliste Internationale (UCI) consensus on nutrition for cycling addresses the nutritional challenges associated with extreme environmental conditions and explores tailored nutrition and hydration strategies to mitigate their effects. The review examines how heat, cold, and altitude affect hydration, energy expenditure, and metabolism, with associated macro- and micronutrient considerations, in cyclists. It discusses practical strategies for managing fluid balance, carbohydrate intake, and micronutrient and electrolyte supplementation and the use of ergogenic aids in supporting adaptation to environmental stresses. This review provides evidence-based nutrition and fluid recommendations for optimizing cycling performance and fostering adaptation in extreme environments. It offers practical guidance on nutrition and hydration strategies before, during, and after training and competition, helping cyclists maintain peak performance while navigating the unique challenges posed by these conditions.