What are the symptoms of dehydration during exercise?

Exercise dehydration is a condition caused by excessive loss of fluids and electrolytes during physical activity. Symptoms become more pronounced as the degree of dehydration increases, mainly including thirst, reduced physical performance, circulatory responses, neurological abnormalities, and changes in urine. A detailed analysis is as follows:

1. Thirst: This is an early typical sign. In mild dehydration, one may only feel slight dryness in the mouth with no strong desire to drink. As dehydration worsens, the oral mucosa becomes dry and thirst intensifies sharply, often difficult to relieve quickly even after drinking water. Some individuals may experience difficulty swallowing.

2. Reduced physical performance: Exercise endurance declines significantly. Activities that could previously be performed easily now feel strenuous and cause heavy breathing. Muscles are prone to cramps and soreness due to electrolyte imbalances and inadequate local blood supply. In severe cases, coordination of limb movements may be impaired.

3. Circulatory system response: Heart rate increases—heartbeat becomes faster than usual even at rest, especially noticeable during exercise. Skin temperature rises but the skin feels dry; capillary refill slows after nail bed compression. Severe dehydration may lead to a slight drop in blood pressure, pallor, and cold extremities.

4. Neurological abnormalities: Early signs include difficulty concentrating, slowed reaction time, and decreased judgment during exercise. As dehydration progresses, symptoms such as dizziness and headache appear. Some people may also become irritable or easily agitated. In severe cases, blurred vision and mental confusion can occur, increasing the risk of sports-related injuries.

5. Urine changes: Urine output decreases significantly. Normally, daily urine volume increases after exercise, but the opposite occurs with dehydration. Urine color changes from normal pale yellow to dark yellow or even amber—the darker the color, the more severe the dehydration, indicating enhanced kidney concentration function.

During exercise, it's important to follow the principle of drinking small amounts frequently, consuming 100–150 mL of lukewarm water or electrolyte-containing sports drinks each time. Be aware of the intensity and duration of your activity. Drink适量 water about one hour before exercising, and maintain regular hydration habits in daily life to reduce the likelihood of dehydration.