About 100 years ago, when I was on the high school track team, Coach Miller "encouraged" us to do "wind sprints". We would jog around the track for a while, suddenly break into a sprint for about 40 yards and then slow down to a walk as our lungs cried out "Please don't do that again."

In the beginning we looked upon this activity as an extreme form of punishment but we learned later that these alternating intensity workouts, now known as interval training, dramatically improved our energy and performance.

Don't panic. I'm not recruiting for the geriatric track team but there is a law of nature at work here that applies to the young or old, fit or fat. Our Creator designed the human body with the miraculous ability to adapt.

Natalie, our adopted granddaughter spent the first thirteen months of her life confined to a crib in a crowded, understaffed hospital in Siberia. Upon arriving in her new home in Dallas, Natalie immediately began to make up for lost time. In a few short months she rushed from crawling to walking to sprinting like an Olympic gymnast.

Natalie's Mom and Dad will attest to the fact that her "normal" activity level accelerated from inactive to an astounding high-energy dynamo.

If you are a couch potato (heaven forbid) or in the "as little as possible" exercise category you too can make dramatic progress in your physical condition by employing the interval training concept. And it will take as little as three 29-minutes sessions per week.

A Canadian study followed exercisers who burned 300 to 400 calories per session. A control group matched the same routine one-third of the time. Two thirds of the time they exercised for a shorter period during which they burned only 225-250 calories-but they included occasional 30-90 second bursts of high-intensity exercise. The fat loss of the group who worked out less was nine times greater than the subjects performing moderate exercise.

Of the three key exercise variables...how often you do it, how hard you work and how long you last, intensity has the most powerful effect. Your body responds to short bursts of intensity by releasing a cascade of fat-mobilizing hormones and anti-aging growth hormones that supercharge your metabolism and burn extra calories for 24 hours or longer.

Fat loss is only one of the benefits. A new study by British researchers tracked 1,975 healthy men over ten years. The men who exercised the hardest had a 47% percent lower risk of death from all causes and a whopping 62% lower risk of death from heart disease, compared with those who reported very little or no intense exercise. The best part however is that these benefits were achieved with as little as nine minutes per day of vigorous activity.

The principle of adaptation also applies to strengthening your muscles, which need to be worked hard to become stronger. The average person loses up to 20 pounds of muscle by age 70 and since each pound of muscle burns up to 50 calories per day it is easy to see why "love handles" and "spare tires" sneak up on us.

Those who are on a low carb diet (I hate the word diet) such as Dr. Atkins Diet or South Beach Diet your exercise has a distinct advantage over the low-fat dieters. Low carbers have a limited amount of glycogen (stored sugar) available and so the body utilizes the fat on the belly, hips and other unwanted places as the primary sources of energy during exercise.

Think you're too old or out of shape to get started on "wind sprints"? It's never too late to start feelin' great!