The misconceptions come from a basic confusion between percentages and absolute amounts. See, at rest, the body is always burning a mix of fuels. All other things being equal, it doesn't like to burn protein, so that leaves fats and carbohydrates (more technically, fatty acids and glucose). At rest, the "average" person burns about 70 percent fat and 30 percent carbs. As one moves from rest to activity, the percentage of fuel coming from fat decreases and the percentage coming from carbs increases. The more intense the exercise, the more carbs and the less fat in the mix, until you reach the point called the "anaerobic threshold" where you're going at about your intensity limit. At that point, 99 percent or more of your fuel is pure carbohydrate and 1 percent or less is coming from fat.

Now, this situation has led many people to assume that in order to "burn fat" they need to exercise at lower intensities. They're missing the boat. Why? Because while at rest, although a higher percentage of your calories is indeed coming from fat, you are ultimately burning a lower absolute number of calories. At higher intensity exercise, the percentage of calories from fat goes down, true -- but it is a percentage of a significantly higher number.

They get the picture.

So, let's say you're exercising at a fairly low intensity that burns, oh, 100 calories in a half-hour. Let's say that 70 percent of those calories come from fat. Your neighbor, however, is working out much harder, outside the magical "fat burning" zone: She's burning up, say 300 calories in that same half hour, but only 50 percent of those calories are from fat. Now do the math. You're burning a higher percentage of fat, but 70 percent of your 100 calories equals 70 fat calories burned. Your neighbor, on the other hand, is burning a lower percentage of fat, but she has burned up 50 percent of 300 calories, or 150 fat calories, more than twice what you've burned in the same period of time!

LEARN THE SCIENCE BEHIND THE AMERICAN COUNCIL ON EXERCISE (ACE)-SPONSORED STUDY THAT DETERMINED THE TOP 5 ABDOMINAL EXERCISES.

A Biomechanics lab at San Diego State University studied 13 of the most common abdominal exercises and ranked them best to worst. The study, conducted by Dr. Peter Francis, Ph.D., involved 30 healthy men and women of varying levels of fitness aged 20-45. Participants were asked to perform a variety of abdominal exercises using their own body weight or both gym and home equipment (including infomercial specialties: Torso Track and Ab Rocker).

Muscle activity was recorded using electromyography (EMG) equipment in the upper and lower abdominals, obliques and hip flexors (hip flexors were measured to indicate how much of the rest of the body was needed to perform the exercise or if the exercise was being done incorrectly). Using the EMG data, the researchers measured the mean muscle activity during each exercise as it compared to the traditional crunch. The exercises were thus rated based on the average amount of muscle activity each movement produced.

The results indicated that exercises that require more abdominal stabilization and rotation of the body -- the Bicycle Maneuver and Captain's Chair -- produced the most activity in the abdominal muscles. However, the most activity produced doesn't necessarily predict the best exercises. There are other factors to consider, including individual fitness level, body mechanics, etc. For instance: Although crunches on an exercise ball produced less muscle activity, they also produced the least amount of activity in the hip flexors, which means it could be considered the best exercise overall for some.

Deciding which abdominal exercises are the best can vary from person to person. Dr. Francis recommends trying 5 minutes of each of the top-rated exercises every day. Continue to do the exercises you like and abstain from movements that you find uncomfortable.

The most important factor is that you find an exercise that works best for you; this will ensure consistency. Strong abdominals are essential for good posture, preventing back pain and well, they look great, too!