Most people know it’s important to stay hydrated (but not too much!) during an intense workout. A sports drink can be an ideal beverage choice, but do you know why? After working out for an hour or so on a hot summer day, you may begin to sweat, get muscle cramps and/or become lightheaded. These are feelings we all recognize, and they may be signs that your electrolytes are low.

Electrolytes are necessary not only to keep up the intensity of game play, but for your body to function properly. They are minerals that dissolve in the blood to form positively or negatively charged particles called ions.

Your body heats up as you exercise. You sweat to lower your core temperature. If you have ever tasted your sweat, you’ll find that it’s a little salty. What you are tasting are the sodium (Na+) and chloride (Cl-) ions, which together are NaCl—better known as table salt. Sweating cools you down, but it also causes you to lose precious ions such as Na+, Cl- and potassium (K+) that the body needs. These ions regulate blood pressure, dictate nerve impulses and even keep your heart beating.

Sports drinks can help correct electrolyte deficiency. The influx of electrolytes from sports drinks also helps regulate the movement of water into your cells. Cells low in electrolytes will lose water and then shrivel up. Once you get more electrolytes from the sport drink, water will flow into the cells to follow the electrolytes. Then the cells will swell back to their normal size, allowing them to regain function.

One of the other main ingredients in sports drinks is sugar, which helps increase the body’s blood sugar (glucose) levels. Glucose is used to fuel the body with energy. This happens when your body breaks down glucose to make ATP, the primary energy source for the cells.

If you occasionally reach the point of cramping and lightheadedness, your electrolytes are likely depleted. To avoid playing catch up after a workout, try to sip a sports drink at least every 20 minutes while performing physical activity. For the best results and recovery, hydrate two hours before a workout and following exercise as well.

If you are the fortunate athlete that doesn’t ever seem to run out of energy, it may be a good idea to pack a sports drink in your gym bag anyway. Clearly, electrolytes do more than prevent lightheadedness and cramps—they keep your body operating as well as it can, so you can perform to the best of your abilities.