Fluids and Exercise

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KEY POINTS

• When you exercise, you lose fluids through your skin as sweat and through your lungs when you breathe. If you don’t replace fluids before and after you exercise, you may get dehydrated, which means that your body does not have enough fluids.
• Drink plenty of water or sports drinks before, during, and after exercise. Most sodas and fruit juices are not a good choice when you exercise because they can cause stomach cramps, nausea, and diarrhea.

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How important are fluids?

When you exercise, you lose fluids through your skin as sweat and through your lungs when you breathe. If you don’t replace fluids before and after you exercise, you may get dehydrated, which means that your body does not have enough fluids. When you are dehydrated, a smaller amount of blood flows through your body. Your heart pumps less blood with each beat and your muscles do not get enough oxygen from your blood. Soon you start feeling very tired and you are at higher risk for heat illness, which can cause muscle cramps, nausea, weakness, and other problems.

How can I prevent dehydration?

Drink plenty of fluids before, during, and after exercise. Thirst is not a good way to judge how much fluids you have lost. If you wait until you are thirsty to replace fluids, you may already be dehydrated. Check the color of your urine throughout the day. If it is usually a dark gold color like apple juice, you are dehydrated. If you are well hydrated, the color of your urine will usually look like pale lemonade.

What types of fluids should I drink?

Drink plenty of water. You can also drink sports drinks to replace nutrients like carbohydrates (sugar), sodium, and protein as well as fluids. Sports drinks with carbohydrates provide energy to working muscles. This extra energy can keep you from feeling tired, especially if you exercise for longer than an hour. Sodium helps your body absorb and retain more water. Protein can help repair damage to your muscles

Most sodas and fruit juices contain too much sugar. They are not a good choice when you exercise because they can cause stomach cramps, nausea, and diarrhea. Carbonated drinks can cause gas.

What are guidelines for fluid replacement?

• Drink 10 to 16 ounces (oz) of fluid about 15 to 30 minutes before workouts.
• Drink 4 to 8 oz of fluid every 10 to 15 minutes during exercise. Choose sports drinks with no more than 14 to 20 grams (g) of carbohydrates, about 110 milligrams (mg) of sodium, and small amounts of other electrolytes (like potassium and chloride) in an 8-ounce (240 mL) serving.