Heat Training Practices in Elite and World-Class Athletes: A Review of Preparation Strategies for Competition in Hot Outdoor Environments

Heat acclimation (artificial exposure) and acclimatization (natural exposure) are key strategies for elite and world-class athletes preparing to compete in hot outdoor environments, aiming to reduce performance impairments and risk of heat illness. Evidence-based guidelines, primarily derived from laboratory studies in non-elite cohorts, recommend 10–14 consecutive days of heat exposure (60–90 min per day), initiated at least 2 weeks before competition in the heat, or earlier if re-acclimation is possible closer to the event. Sessions should elicit sustained elevations in core and skin temperature, skin blood flow, and sweating. However, logistical constraints, training demands, and tapering often limit protocol implementation in elite and world-class athletes, prompting the adoption of alternative approaches. This review synthesises observational studies documenting heat training practices in these athletes and evaluates their alignment with current guidelines. Eleven of the 12 studies included sport-specific heat exposure within preparation for competition in hot environments, often in similar or more severe environmental conditions than competition, with five studies incorporating post-exercise passive heating. However, heat intervention design, session structure, and monitoring of thermal and cardiovascular strain varied widely, with many reports lacking sufficient detail to determine their effectiveness at inducing and retaining adaptations outside laboratory-controlled settings. Nonetheless, initial reports indicate that classical markers of heat adaptation such as reduced exercise heart rate and core temperature, and increased plasma volume, are commonly observed. Standardized documentation of heat training characteristics is needed to assess their effectiveness in high-performance sport and refine evidence-based guidelines.