Heat injury can occur in athletes (as well as nonathletes) during exercise performed at high temperatures and high humidity. While heat injury can easily impair performance, more importantly, when ignored it can progress to the point of serious danger. Early indications of heat injury include dizziness, nausea, tingling sensations, and so forth, which can lead to heat stroke and even death if not kept in check. Physiological factors that often accompany heat injury include elevated body temperature, dehydration, and electrolyte imbalance. Many heat injuries can be prevented by adaptation to the thermal environment in which exercise will take place and consumption of adequate fluids prior to and during exercise. Additional precautions that can be taken to reduce the risk of heat injury include exercising during the coolest time of the day and wearing lightweight, comfortable clothing.