darned “deconditioned,” as the politically correct like to say, even exercising
at 50 percent of your maximum heart rate can help build up your fitness level.
You may have heard that exercising at a slow pace is more effective for
weight loss than working out more intensely. In fact, many cardio machines
have “fat burning” programs that keep you at a slow pace. But this is mislead-
ing. As it turns out, the concept of a fat-burning zone is no more real than the
Twilight Zone.
During low-intensity aerobic exercise, your body does use fat as its primary
fuel source. As you get closer to your breaking point, your body starts using
a smaller percentage of fat and a larger percentage of carbohydrates, another
fuel source. However, picking up the pace allows you to burn more total calo-
ries, as well as more fat calories.
Here’s how: If you go in-line skating for 30 minutes at a leisurely roll, you
might burn about 100 calories — about 80 percent of them from fat (so that’s
80 fat calories). But if you spend the same amount of time skating with a
vengeance over a hilly course, you might burn 300 calories — 30 percent of
them from fat (that’s 90 fat calories). So at the fast pace, you burn more than
double the calories and 10 more fat calories.
Of course, going faster and harder is not always better. If you’re just starting
out, you probably can’t sustain a faster pace long enough to make it worth
your while. If you go slower, you may be able to exercise a lot longer, so you’ll
end up burning more calories and fat that way.
Which activities burn the most calories ........................................
“Maximize your workout and burn over 1,000 calories per hour!” That’s a
claim you may see in advertisements for treadmills, stair-climbers, and other
cardio machines. And it’s true. You can burn 1,000 calories per hour doing
those activities — if you crank up the machine to the highest level and if you
happen to have bionic legs. If you’re a beginner, you’ll last about 30 seconds
at that pace, at which point you will have burned 8.3 calories, and the para-
medics will be scooping you off the floor and hauling your wilted body away
on a stretcher.
There’s a better approach to calorie burning: Choose an activity that you can
sustain for a good while — say, at least 10 or 15 minutes. Sure, running burns
more calories than walking, but if running wipes you out after a half mile or
bothers your knees, you’re better off walking.
Table 8-2 gives calorie estimates for a number of popular aerobic activities.
The number of calories you actually burn depends on the intensity of your
workout, your weight, your muscle mass, and your metabolism. In general, a
beginner is capable of burning 4 or 5 calories per minute of exercise, while
a very fit person can burn 10 to 12 calories per minute.
Chapter 8: Cardio Crash Course 119