Heat exhaustion is best described as

• A. Inability to exercise in the heat due to cardiovascular insufficiency, hypotension, energy depletion, and central fatigue
• B. Elevated core temperature, high skin blood flow, heavy sweating, and dehydration
• C. Occurs most frequently in hot and humid condition
• D. Most often affects unacclimatized or dehydrated individuals with BMI > 27

Answer: (A)

Heat exhaustion happens when the body's ability to dissipate heat during work in hot conditions is overwhelmed by dehydration and reduced blood volume. The core issue is cardiovascular strain: the heart and circulatory system can’t keep up with the demand for blood to the skin for cooling and to the muscles for activity, so you feel lightheaded, weak, dizzy, and fatigued. This makes continuing exercise in the heat difficult or impossible, and hypotension and energy depletion (central fatigue) reflect that reduced circulatory efficiency. This description best captures the underlying mechanism and primary symptom—an exercised person unable to continue due to cardiovascular and fluid-related strain—in contrast to other heat illnesses. While hot, humid conditions and dehydration raise risk, and unacclimatized or dehydrated individuals are more susceptible, those are risk factors rather than defining features of heat exhaustion.