Whew! It's hot today! But you still can't wait to hit the playground for recess. You swing for a while, play tag, and then finish up with a quick game of kickball. When it's time to head back inside, sweat is dripping down your forehead.

As you make your way back to your classroom, a trickle of sweat leaks down the side of your face to the corner of your mouth. You lick your lips and you can taste a salty flavor. You look forward to a quick trip to the bathroom to wash up and dry off.

Whether it's after recess, a sports practice or an intense exercise session, we've all noticed the salty tang of sweat at some point. Have you ever WONDERed, though, exactly why sweat is so salty?

Sweat, also known as perspiration, is your body's way of cooling itself. Your body's optimum temperature is about 98.6º F. When you exercise, especially when it's hot outside, your body's temperature rises. When that happens, your brain sends a message to your sweat glands, telling them to produce sweat that then gets secreted through the pores in your skin. The average human being has over 2.5 million sweat glands!

When the sweat reaches the surface of your skin, it evaporates. That means the air turns the sweat from a liquid to a vapor. This creates a cooling effect that helps to lower your body temperature. The more you exercise, the more sweat is produced in order to continue cooling your body.

In cooler climates, the maximum amount of sweat a person can normally produce is about one liter per hour. In hotter climates, however, people adapt and their bodies can produce as much as two to three liters of sweat per hour.

Sweat is mostly made up of water. There are small amounts of other chemical compounds, though. For example, sweat also contains ammonia and urea, which are produced by the body when it breaks down proteins from the foods you eat. Sweat also contains sugar and salts, such as sodium, chloride, and potassium. This explains the salty taste you experience when a drop of sweat finds its way to your taste buds.

Many people don't like to sweat. They don't like the wet feeling it leaves on their skin and clothes. Many people also don't like the smell, either. However, don't blame the sweat! By itself, sweat doesn't stink. It's the bacteria on your skin that mixes with sweat that gives it a foul odor sometimes.

Even if you don't like to sweat, you should be very glad that you do. Without sweat, your body could quickly overheat, leading to sickness or even death. If you don't like the side effects of sweat, such as wetness or odor, bring along a towel, a change of clothes, and some deodorant or anti-perspirant.

And when you're done exercising? Be sure to refuel! Your body can lose a lot of water through sweating. So make sure you drink plenty of water after sweating a lot, so that your body won't get dehydrated.

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