Sweat it: perspiration is nature's way of cooling hot muscles. But it can also leave you physically depleted and socially undesirable

Men's Fitness, March, 2003 by Matthew Solan

A drenched shirt is a symbol of a great workout. But all that sweat isn't there to pat you on the back--and then trickle down it--for a job well done.

"Sweating cools your body during exertion, whether that extra heat comes from hardworking muscles, overstimulated nerves, or hot air temperature," says Paula E. Papanek, Ph.D., director of exercise science at Marquette University in Milwaukee, Wis.

DURING A WORKOUT, the heat produced by your muscles exceeds the heat released by the body, making your temperature rise. This stimulates the sweat glands, which filter a secretion of mostly water, sodium chloride and potassium onto the surface of your skin. When it evaporates, your temperature is reduced. (This is also why you get the sweats when you have a fever.)

THE AVERAGE JOE has 2.6 million sweat glands in his skin--weighing a total of three ounces--that cover the entire body except for the lips, nipples and genitals. There are two types: Eccrine glands, found on the arms, back, chest, palms, soles and forehead, are the most plentiful; apocrine glands are located primarily in the armpits and groin.

Sweat produced by the apocrine glands contains proteins and fatty acids, which make it thicker and give it a milky or yellow color--the cause of those unsightly underarm stains. The secretion itself has no odor, but when bacteria on the skin and hair metabolize the proteins and acids, the sweat becomes "scented." This is why your wet chest doesn't reek like your armpits do.

IN WARM CONDITIONS, men can lose between one and 2 1/2 liters of sweat during each hour of training. A greater degree of fitness--or moving to a hotter climate--can increase sweat production to two or three liters per hour.

REPLENISH YOURSELF

The old rule for workouts is to consume six to eight ounces of [H.sub.2]O every 15 to 20 minutes to avoid dehydration. But a study in the International Journal of Sports Nutrition suggests that your fluid intake should be between 150 percent and 200 percent more than the volume of sweat lost. In other words, double your efforts.

YOU ALSO NEED to worry about losing too much sodium, cautions Michael F. Bergeron, Ph.D., of the Medical College of Georgia in Augusta. Each liter of sweat contains about 1.8 grams of salt. "If you don't replace it, you risk upsetting the balance of sodium around specific nerve endings and muscle fibers, which can trigger muscle cramps, especially in the late stages of demanding sports like football, triathlons, cycling and tennis," he says.

WHEN THIS HAPPENS, you need more than just water, which has only seven milligrams of sodium per eight ounces. Bergeron suggests:

* Gatorade (110 mg sodium per 8 oz.)
* Powerade
  (55 mg)
* Tomato juice
  (882 mg)
* High-salt foods
  such as pretzels
  (483 mg per
  stick)
* A slice of whole-wheat bread
  (159 mg)

DON'T WAIT UNTIL you've lost a ton of sodium to begin slugging sodium-light fluids. This can cause hyponatremia, or "water intoxication," wherein the kidneys cannot excrete fluids as quickly as they're consumed. Signaled by nausea, dizziness and fatigue, hyponatremia can be extremely dangerous if left untreated.

STRESS SWEAT

As for stress-induced perspiration, emotional pressure tends to trigger an excess of apocrine-gland secretions, which is why nervous sweat is so odoriferous. Consider relaxation techniques such as meditation or simple deep-breathing exercises; cutting back on caffeine and spicy foods also helps.

Sweat is usually medically benign. Just keep your hydration high, stay salted, wipe down the weight bench when you're done, and make sure to wash both yourself and your shirt before you interact with human beings again.