American Medical Association Family Medical Guide - American Medical Association [41]
Aerobic exercise is a good way to reduce the relative amount of fat on your body and boost the amount of muscle. It also burns excess calories, which helps you control your weight. People who maintain a healthy weight have a reduced risk of heart disease, diabetes, some cancers, and other health problems that have been linked to being overweight or obese.
Aerobic exercise also improves your mood. People who do aerobic exercise regularly say that they feel better emotionally and mentally. When you engage in aerobic activity, your body produces chemicals called endorphins, which alter brain chemistry to brighten your mood and reduce pain. If you are like most people, you will feel relaxed after aerobic exercise and you will sleep better.
Doctors recommend engaging in aerobic exercise for 30 to 60 minutes every day. Try to reach a heart rate (beats per minute) that is 50 to 80 percent of the maximum rate for your age. This rate is called your target heart rate (see below). If your heart rate does not reach this range, adjust the intensity of your activity until it does.
Remember to warm up for 5 minutes before every exercise session and to cool down afterward. Begin by stretching the muscles and joints in your spine, arms, and legs and then walk, jog, or bike slowly to raise your heart rate slightly and prepare it for the more intense activity to come. Warm-up and cool-down exercises can increase your flexibility and help prevent injury to your muscles and joints.
Finding Your Target Heart Rate
It’s easy to calculate your target heart rate. Let’s say that you’re 40 years old. First, subtract your age from 220 (220 - 40 = 180). The resulting number (180 beats per minute) is your maximum target heart rate. To find your target heart rate range, multiply that number by 50 percent to find the low end and 80 percent to find the high end (180 × 0.50 = 90 and 180 × 0.80 = 144). Your target heart rate range is 90 to 144 beats per minute.
The easiest way to check your heart rate is to count your heartbeats for 6 seconds right after an exercise session and multiply that number by 10 to find the number of heart beats in a minute. To count your heartbeats, place the tips of your middle and index fingers (don’t use your thumb) on your throat to one side of your Adam’s apple or on the inside of your wrist. As soon as you feel your pulse, start counting the beats for 6 seconds. Multiply the number of beats by 10. If your rate is below or above your target heart rate range, adjust your exercise by making it more or less strenuous.
Taking your pulse
To take your pulse, place the tips of your middle and index fingers (not your thumb) on your throat to one side of your Adam’s apple (top) or on the inside of your wrist (bottom). When you feel your pulse, start counting the heartbeats.
Staying Strong as You Age
Muscle-building exercises continue to be essential to good health as you age. As you get older, you lose up to half a pound of muscle every year, and the muscle is replaced by fat. This process translates into a 1 to 2 percent loss of strength each year. Over time, the loss in strength can reduce your ability to move, ultimately resulting in a loss of physical independence in old age. Performing strengthening exercises regularly two or three times a week does the following:
• Improves your balance, reducing falls.
• Strengthens your bones, reducing your risk of osteoporosis and fractures.
• Boosts your metabolism (the chemical processes that take place in your body), increasing the rate at which you burn calories.
• Relieves pain from