Dizziness, nausea, and headache occur. To avoid this, do not drink or eat something sugary within two hours before heavy exercise. Fruit juices or sports drinks taken after heavy exercise are better than water for rehydration. Sports drinks are very effective in reducing dehydration. Drink them during or after hard work or long exercise sessions, not before.
Sports drinks rehydrate the body faster and more thoroughly than water alone.
Thirst is prolonged by the minerals in sports drinks. This keeps people drinking until fully rehydrated. For a 20 to 30 minute exercise, water works well to avoid dehydration. Take a cup of water one-half hour before exercise and at least a cup immediately after exercise. Electrolytes can be found in most sports drinks.