Sweat as an emotions barometer--and more

Not long ago, I was taking care of my daughter who was recovering from complicated surgery on her hand. I was also helping with the dog walking. I noticed that my feet were often sweaty during my stint—slipping around in my flip-flops. Though the weather was hot, I knew that sweating on the soles of my feet happens under stress because this has happened to me before. Apparently I was more nervous about this care-taking activity than I was conscious of.

The kind of sweat glands on your feet, as well as everywhere else on your body, are called eccrine sweat glands. (A second kind, called apocrine, are mostly limited to your armpits and anus area. I’m sticking with eccrine sweat glands in this post.) Sweat glands, which are controlled by your nervous system as well as hormones, are particularly numerous on your feet, palms, face, and armpits. (Our palms have around 370 sweat glands per square centimeter.) For our primitive ancestors, having lots of sweat glands on their hands and feet increased friction and enhanced grip—part of the fight or flight mechanisms. Sweat also cools our skins, reduces body temperature, allows us to get rid of excess water and electrolytes and helps to protect our skin from bacterial colonization.

Because it is derived from your blood plasma, sweat is 99 percent water, but also contains sodium, chloride, and other elements. When all of your sweat glands are working at maximum capacity, you can lose more than three liters per hour. But you normally sweat about a quart a day. You may be one of those who gets muscle cramps after sweat-inducing exercise. This is generally the result of losing electrolytes (sodium, etc.). I understand that drinking two-and-a half ounces of salty pickle juice almost instantly relieves the cramping. If you try this, let me know if it works.

Sweat is odorless. It’s the interaction with bacteria that causes the odor. Deodorants work by killing the bacteria on your skin. Antiperspirants, which are classified as drugs, block the top of your sweat glands and plug them up (doesn’t sound like a good idea to me). You may have noticed, as I have, that polyester clothes are stinkier than cotton. That’s partly because polyester is less absorbent than cotton, a characteristic that helps promote odor-causing bacteria. But it also promotes a different type of bacteria than cotton—the kind that degrades fatty acids and amino acids into “malodorous compounds,” as one researcher explains it. Malodorous I don't want to be. I'm sticking with cotton.

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