By Therese Iknoian

Never-say-die myths about exercise, sports and nutrition just...well...never say die. Oh, you've learned better over the years. But the advice of an old high school coach, college frat buddy, or even your mother can creep back into your brain, begging for acceptance.

Here's one installment in the battle to fight the baloney:

• Sweating means I'm melting fat. The scale proves it because I weigh less after a hard workout.

  Sweat is water, and losing water without replenishing it is not healthy. If you weight less after a workout, you're dehydrated, which means your muscles and nerves won't function as well, and you'll be slugglish and thirsty. A post-exercise loss of more than 2 percent of your body weight impairs the body's ability to run smoothly. A 5-percent loss is downright dangerous. Excess fat is metabolized by aerobic exercise and eating less. No magic, just dedication and discipline. Darn.

• Doing abdominal exercises shrinks the fat in my gut, just as doing leg lifts reduces the size of my thighs.

  And the tooth fairy really does leave money under your pillow. Spot reducing is a tall tale that just won't die. If you have a spare tire, doing abdomninal crunches will give you a gut as hard as steel-under the spare tire. The solution? Aerobic exercise and eating less. Dedication and discipline. Where have I heard this before?

• Weight lifting burns my extra fat.

  Lifting iron makes you stronger-under the extra fat. Sure, weight lifting is great, because it keeps muscles and bones strong and functional. Strength training should be a part of any exercise program partly because it does build muscle, and more muscle can burn more calories. But, all together now, the solution for getting rid of fat is aerobic exercise and eating less. Dedication. Discipline. Double darn.

• If I don't have time for 30 continuous minutes of aerobic exercise such as running, walking or bike riding, I shouldn't bother because any less won't do me any good.

  Good excuse, but it doesn't pan out. Recent studies show that three, 10-minute bouts of exercise-say a brisk walk at lunch, on a break, or after work-provide health benefits for your heart and lungs comparable to 30 non-stop minutes. No, you won't lose as much weight as with 30 minutes, but you'll do the cardiovascular system a lot of good. Plus, a brisk walk around the building jawing with a friend, instead of to the cafeteria to chow down a chocolate-chip cookie, will save you from devouring extra calories.

© 1999 Therese Iknoian