Heat exposure concerns athletes of all levels, during competition and training. It increases thermoregulatory, cardiovascular, and perceptual strain, may impair performance, and raises the risk of heat-related illness. When competition in hot conditions is expected, heat acclimation remains the key intervention and should be individualized according to the sport, timing, tolerance, and vulnerability factors. Hydration, nutrition, and cooling strategies complement this approach, but they do not replace it. In selected situations, heat may also serve as a training stimulus to induce physiological adaptations or increase cardiovascular and metabolic effort without increasing mechanical stress to the same extent. It requires a clear objective and predefined stopping criteria.