What are heat cramps and what causes them?

Heat cramps are painful muscle contractions that typically occur during or after intense physical activity, especially in conditions of high heat and humidity. They are linked to significant loss of water and electrolytes, particularly sodium, through sweating. When the body loses these essential fluids and salts, it can lead to a disturbance in the normal function of muscles, resulting in involuntary and painful spasms.

The correct option identifies this relationship between muscle pains and spasms specifically with dehydration and electrolyte imbalance. Proper hydration and maintaining electrolyte levels are crucial to prevent heat cramps during physical exertion, especially in hot weather. Recognizing these symptoms is vital for providing appropriate first aid and treatment to the individual experiencing heat cramps, which may include rehydration and rest.

In contrast, the other options do not accurately describe the cause of heat cramps. For instance, pain in the legs from fractures pertains to injuries rather than muscular issues stemming from heat and hydration. Muscle pains from prolonged inactivity are related to lack of movement rather than heat exposure. While increased body temperature from exercise is a factor that allows for the occurrence of heat cramps, it is not the direct cause; rather, it is the loss of fluids and salts during this time that triggers the cramps themselves.