What serious condition can occur due to dehydration during exercise?

Dehydration during exercise can lead to heat exhaustion, which is a serious condition characterized by excessive loss of body fluids and electrolytes. When the body does not have enough water or electrolytes, it cannot effectively regulate its temperature. This can result in symptoms such as heavy sweating, weakness, dizziness, nausea, and fainting. Heat exhaustion occurs when the body struggles to cool itself, particularly in hot and humid conditions, making it crucial for individuals engaging in physical activities to stay adequately hydrated to prevent this potentially dangerous condition.

While muscle fatigue can occur with dehydration, it is more a symptomatic effect of physical exertion rather than a serious condition. Hypothermia is related to excessive heat loss and typically occurs in cold environments, making it irrelevant to dehydration during exercise. Cardiac arrest is a critical medical condition but is not directly caused by dehydration in the context of exercise; it may be a consequence of severe electrolyte imbalances or other health issues exacerbated by dehydration. Therefore, heat exhaustion is the most accurate answer, highlighting the critical importance of hydration during physical activities.