Calories—we count them and we cut them, yet we need them to live and breathe. A calorie is a unit of energy. Specifically, it is the amount of energy, or heat, required to raise the temperature of 1 gram of water 1 degree Celsius. One calorie is equal to 4.184 joules.
The cliché of "you are what you eat" is true, in that what we eat influences nearly every phase of metabolism. Some of the nutrients we eat are needed so that we can breathe, think and maintain resting levels of organ function, called basal metabolic rate. We require 700-1,400 calories a day to function. The other calories we take in—the calories we'd like to burn up—are actually not used directly for exercise, but rather to produce ATP, a molecule known as adenosine triphosphate. The rest of the time we use stored carbohydrates and fat and sometimes protein as a backup to regenerate ATP.
The more you exercise, the more you expend energy, preserve your muscle mass and release your fat stores. Slow-twitch muscle fibers, the kind used primarily in cardiovascular workouts, increase in size between 7 and 22 percent. This expansion increases the cells' ability to burn more calories. The enzymes responsible for speeding up the breakdown of fat molecules are also enhanced, as are the capillaries surrounding muscle fibers. There is also a big increase in the size and number of mitochondria, the fat-burning furnace in cells.
So what is the best way to burn calories? Can you believe the calorie readouts on machines? And are you doing enough to shake up your system so that you burn more calories when you exercise?
Breathing hard when you work out saturates your cells with oxygen and increases your caloric output. However, are the caloric readouts correct on machines? The American College of Sports Medicine uses various equations that can estimate energy expenditure for activities like walking, running and cycling. The equations use resting energy, at about 5 kcal per liter of oxygen, to provide the gross oxygen consumption of specific exercise. For example, the gross calorie cost of a 154-pound person walking a 20-minute mile is 80.5 calories.
To arrive at the net cost involves subtracting the energy costs of resting oxygen uptake. Equating this information into the formula comes up with a caloric equivalent of 24.5 calories, so the actual caloric expenditure is 56 kcal per mile. The problem with many cardio machines is that they can overestimate calories used by using gross energy expenditure calculations instead of net values. Keep this in mind, as the lower the exercise intensity, the greater the error between net and gross energy expenditure. For specific energy estimations, go to www.webmd.com/diet/healthtool-fitness-calories-counter.
You might be sabotaging your efforts with a few bad habits. On steep grades on a treadmill, don't lean back and hold on to the console, or push down with your hands on stair machines, locking your elbows. The calorie readouts will greatly overstate the actual energy expenditure. Instead, put your full weight on your feet and use the handrail supports only for balance. Also, carrying handheld weights when you walk or run may burn a few more calories, but research shows that the additional weights don't improve your overall aerobic capacity. Instead, pick up your pace; you can increase your caloric burn from 3.5 calories a minute walking at 3 mph, compared to burning 5.2 calories a minute walking at 4 mph.
Go quite hard
Interval training, which breaks up higher-intensity efforts with short rest periods, is a fast way to mobilize your fat stores. Try one or two of these each week, or modify them as needed. Each of these should include a warm-up and cool-down.
· 10 x 30 seconds fast with one-minute active recovery periods.
· 5-6 x 3 minutes at 95 percent maximum heart rate with two-minute active recovery periods.
· Two-, four- and six-minute bouts of exercise on different pieces of equipment, changing the intensities. Called Fartlek, or speed training, this indoor "play" workout is a lot of fun, using both aerobic and anaerobic energy pathways, all contributing to fat burning:
· Rotation 1: treadmill (two minutes), elliptical trainer (four minutes), bike (six minutes).
· Rotation 2: elliptical trainer (six minutes), bike (four minutes), treadmill (two minutes).
· Rotation 3: bike (four minutes) treadmill (four minutes), bike (four minutes).
Intensity: For the two-minute duration, go hard; for the four-minute duration, go somewhat hard; and for the six-minute duration, go between light and somewhat hard.
Go very long
Long bike rides or runs lasting over an hour and up to two hours, at approximately 65 percent max heart rate, will truly develop your ability to be a better fat burner by increasing your endurance. As your body uses up its carbohydrate stores, in the form of glycogen, muscles "learn" how to use fat more efficiently and over time become better fat-burning factories. Above all, our bodies love to move, anyway you choose.
Connie Aronson is a Ketchum-based health fitness specialist and personal trainer.