- Running 3 miles in 24 minutes (8-minute miles)
- Walking 5 miles in an hour and a half (3.5 mph)
- Swimming 1,200 yards in 24 minutes (50 yards per minute)
- Cycling 10 miles in 45 minutes (about 13 mph)
(In each of these exercises, an individual who weighs more than 200 pounds would burn about 30 percent more calories. One who weighs less than 125 pounds would burn about 30 percent less.) Any one of the above exercises will do for your program. I'm going to talk about walking and or jogging because that's the easiest and I've had the most experience with it.
If your exercise is walking briskly, or jogging, I'd like to have you do it for about half an hour. Early on in your program, when you're just starting to exercise, you may not be able to last half an hour at a brisk walk or jog. So when you're tired, and can't keep on so briskly any more, just slow down for a while. But try to keep on walking, even at a reduced pace, for the whole of the half hour.
If you've received an exercise prescription you have probably been advised to do your aerobic exercise at a particular heart rate. If you haven't been given a Training Heart Rate (THR), you should calculate it, using our formula—your THR is eighty percent of your Predicted Maximum Heart Rate (see page 306).
If your exercise is keeping you at your Training Heart Rate, it's probably the right intensity for you—but here's another way to tell. It's called the Talk Test. While you're walking briskly or jogging you should be able to carry on a conversation with someone who's jogging along with you. You may sound a little breathless, but you should be able to carry on a conversation.
If you're pushing too hard you'll be breathing too rapidly and deeply to be able to talk—and that means your muscles are building up lactic acid and releasing it into the bloodstream too fast, you aren't getting enough oxygen, and it's time to slow down.
Here's another test. If you're doing aerobic exercise you should be generating heat so that you feel noticeably warmer than when you started. And you may even be working up a bit of a sweat.
One other thing: you may get a “stitch” (a pain in the side) after you’ve been running for a while. I remember, when I was a kid, I got a stitch in my side nearly every time I ran. When I got to medical school I asked my professors what caused these stitches, and after consultation among themselves, they told me they didn't know. I was pretty disappointed. But there are a lot more runners around now, and we know a lot more about the many problems they come up with. Dr. George Sheehan, who wrote a column in Runner's World and published more than ten books on running before his death in 1993, said that stitches in your side are the result of improper or inadequate movement of the abdominal muscles during exercise: This comes about when we breathe mainly with the chest instead of the abdomen.
Do you have a problem with stitches? You can find out for yourself whether you're a chest breather or a belly breather by standing up, with one hand on your abdomen and one on your chest, taking ten deep breaths, and seeing which hand moves. If you're breathing properly with your belly, when you take a deep breath in, the hand on your belly will move out, and when you breathe out again, your hand will move back in. The chest needn't move very much at all.
Abdominal, or belly breathing, is something that people in any occupation or endeavor in which breathing is important have to learn— singers, actors, public speakers, athletes and joggers.
If you do the simple test I suggested, and find out that you're not breathing abdominally, it takes a little practice to learn it. But it's worth it. When you've learned abdominal breathing you'll never have to have a stitch in your side again. Or, if you do, you'll know what to do about it—breathe in an exaggerated manner with your belly as you continue exercising at a slower pace.
Author: Cleaves M. Bennett MD FACP
Aerobic exercise is exercise that moves the larger muscles freely, generates heat in the body, and thus burns up oxygen: Aerobic exercise generally makes you breathe more heavily than you would at rest and causes you to work up a little bit of a sweat. Read More