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Workouts and Your Body

How Your Body Responds to Exercise
While virtually everyone knows that working out makes you look and feel good, not that many know how and why. What happens physiologically when you exercise? Let's look at how your body responds to different types of exercise.

Cardiovascular Exercise
Your cardiovascular system is made up of your heart, lungs, and blood vessels. With continued exercise, your cardiovascular system becomes stronger and more efficient. As we mentioned earlier, as your heart becomes stronger, it is capable of ejecting more blood with each beat. (This is known as your stroke volume.) This means that your heart doesn't have to beat as often. In addition, your lung capacity increases and your muscles are capable of extracting more oxygen from the blood as it's delivered to the exercising muscle. Other benefits of cardiovascular training are lowered blood pressure at rest and improvements in your cholesterol.

Strength Training
What happens to a muscle when you lift weights is one of the simplest, yet most misunderstood areas of physiology. Here's the scoop. When you force a muscle to work hard, as in strength training, it increases in size and strength. Simple. This happens by the growth of each individual muscle fiber in a particular muscle. Despite what you may read in some publications, strength training does not increase the number of muscle fibers. In addition, the connective tissue around the muscle increases in strength as well.

Contrary to the myths floating around most gyms (not to mention books and videos), lifting doesn't make a muscle smaller or longer, no matter how many reps you do or what weight you use. Think about it: That guy in the corner of the weight room doing biceps curls isn't doing them to make his arms smaller, yet we often see women doing leg extension or hip exercises in the hopes of "slimming" their thighs. Sorry tummy tuckers, it doesn't work that way. Keep that in mind next time you see someone doing side bends hoping to reduce her waistline.

Most people know that they should stretch, but they don't really understand why or what happens when you properly stretch a muscle. Here's a quick rundown.

Stretching allows your muscles to retain elasticity, which prevents injury. With repetitive activities – running, cycling, weight training – certain muscles are used over and over again, which effectively shortens the muscles. This leads to something known as muscular imbalance. When a muscular imbalance occurs, the stronger muscles take over the work of the weaker muscles, causing the weaker muscles to lose so much strength that strains, sprains, and tendinitis occur.

Weight Loss
Clearly, losing weight is a frustrating topic for millions of Americans. The good news is that there's a simple formula for weight loss: Eat less and exercise more. Okay, it sounds glib, but it's true. Of course, while it is simple, it's not easy! Nevertheless, the way you lose weight is by burning more calories than you take in. A pound of fat has 3,500 calories worth of energy. That means in order to lose one pound, you need to create a "caloric deficit" of 3,500 calories. The best way to do this is with a combination of decreased caloric intake and increased caloric expenditure.

Here's a nice, neat textbook example. If you decrease your daily intake by 250 calories and increase your activity level enough to burn an extra 250 calories, you'll have a caloric deficit of 500 calories for the day. Multiply that by seven days in a week, and you've got 3,500 calories for the week.

Detraining – Missing Workouts
Now that we've discussed what happens when you work out, let's look at what happens when you don't. (If you're an obsessive-compulsive like Jonathan it means a copious level of angst and guilt.) Surprisingly, many athletes who train often and hard find improved performance after a short layoff. That's due to the fact that many of them are overtrained and in need the rest. Of course, an extended layoff can cause a significant loss in fitness. While there's far less research and information on the topic of detraining than there is on training, there are some basic things to note.

After as little as two weeks of inactivity, there can be measurable decreases in aerobic capacity and muscular strength. This is all the more reason to do all you can to remain active. Remember, just two 30-minute weight-lifting workouts are enough to maintain and even gain strength. Similarly, two or three cardiovascular workouts lasting as little as 15 to 20 minutes can help keep you in shape.

As you read this book, remember that you need to do all you can not to miss workouts. The good news is that we'll help you find the time as well as provide workouts that take less time to maintain or improve your fitness.

The Least You Need to Know

  • Before embarking on an exercise program, save time and energy by deciding what your needs and goals are.
  • Working out is not only for looking good, there are numerous health benefits that a consistent fitness program will provide you with.
  • Muscle size is a function of genetic predisposition; women are not naturally capable of getting muscle-bound by weight training.
  • If you want to lose weight, eat less, exercise more.


Excerpted from The Complete Idiot's Guide to Short Workouts © 2001 by Deidre Johnson-Cane, Jonathan Cane, and Joe Glickman. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.

To order this book visit the Idiot's Guide web site or call 1-800-253-6476.

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