Exercise Article Index >> Cardiovascular Exercise: How Much? Which is considered an aerobic activity: Sprinting uphill to the catch the bus or an hour of shopping at the supermarket? If you answered neither, you are correct. The term aerobic, made popular by Dr. Kenneth Cooper in the late 1960s, is derived from Greek roots -- aero, or air; and bios, or life. Since aerobic training plays a role in the prevention of cardiovascular disease, it's often called cardiovascular training. No matter what you call it, in order for an activity to be aerobic it must be rhythmic in nature, use large muscle groups and be maintained continuously for 20 to 60 minutes. In addition, it must challenge the heart and lungs, without overdoing it. Walking, hiking, swimming, running, cycling, rope skipping, rowing, stair climbing and group fitness classes such as low-impact aerobics and indoor cycling are all aerobic. The idea behind aerobic training is that oxygen is continuously delivered to your muscles. While sprinting to the bus is admirable, it is considered an anaerobic activity, which means "without air." You know what happens: You run uphill, the bus pulls away and you try to continue running, but you're out of breath and your leg muscles are burning. That's because the oxygen is no longer being delivered to your muscles. Your anaerobic system is designed only for those short bursts of intense activity. Regular aerobic training will improve your anaerobic performance -- you will catch the bus in a month or two. Supermarket shopping, on the other hand, will burn some calories, but it's not rigorous enough to be considered aerobic. How Hard, How Often? There is a very simple way to determine how much aerobic exercise you need. It's called the FIT formula, and it was developed by the American College of Sports Medicine (ACSM). F = Frequency: Three to five times per week. I = Intensity: 60 percent to 90 percent of maximum heart rate. (This range is also known as your target heart rate range.) T = Time: 20 to 60 minutes of continuous activity (excluding warm-up and cool-down periods) or a minimum of two, 10-minute bouts in a day. Intensity plays an important role in the FIT formula, and it's the hardest factor to judge. You can determine the intensity of an activity by monitoring your heart rate and staying in your target heart rate range. To find your range, try our target heart rate calculator. You can also use the Rating of Perceived Exertion. The RPE, a scale developed by exercise researchers, asks you to rate on a scale of 1-10 your answer to the simple question, "How do you feel?" Zero means you are not exerting yourself at all; 10 means you have reached your maximum possible exertion. Rating of Perceived Exertion Examples 0 No exertion Resting on the sofa 1 Very weak 2 Weak 3 Moderate Strolling or light gardening 4 Somewhat strong 5 Strong 6 Strong 7 Very strong Jogging briskly 8 Very strong 9 Very, very strong 10 Maximal exertion Sprinting uphill to catch the bus Use this scale to gauge how hard you're pushing throughout your workout. Every five minutes or so ask yourself, "How do I feel?" Aim for an RPE between four and five. The talk test is another simple way to gauge your intensity. While performing any aerobic activity, you should be able to carry on a casual conversation without becoming breathless. Using a combination of tools, you should be able to monitor your intensity level properly. Now that you've learned how to monitor your intensity, which level is best? A few years back, a popular theory held that aerobic exercise performed at the low end of the target heart rate zone for a longer time (for example, 75 minutes of exercise at 60 percent of your maximum heart rate) would burn more fat than a higher intensity, shorter workout (such as 40 minutes at 80 percent). Why? At lower intensities fat is used as the primary fuel; at higher intensities, glycogen -- the major carbohydrate stored in our cells -- is used. So, if fat burning is your goal, it seems to make sense to exercise longer at lower levels. But, that's only half the story: Since fewer calories are burned at lower intensities, not as much total fat is burned. That's not to say that you should work at 90 percent of your maximum heart rate for 20 minutes a day and be done with it. Working that hard would be counterproductive. In fact, the ACSM recommends this intense style of training for those engaging in athletic competition. The Importance of Steady Progress Remember that conditioning is progressive. According to the ACSM, conditioning can be broken down into three stages. The "initial stage" of conditioning lasts four to six weeks. According to the group's guidelines, most beginners should start at 40 percent to 60 percent of their target heart rate for 12 to 15 minutes at a time (not including warm up and cool down periods). For some, this may be too much. But remember, regularly working at 50 percent of your maximum heart rate will still reduce your risk of high blood pressure, diabetes and heart disease. The "improvement stage" of conditioning lasts about four to five months, says the ACSM. During this stage, gradually increase your intensity level to 70 percent to 80 percent of maximum heart rate. Every two or three weeks, increase the duration of your workout, too, until you can exercise for 20 to 30 minutes continuously. The "maintenance stage" begins after the first six months of training. Improvement is minimal, but it keeps getting better slowly. Performing the same fitness routine should enable you to maintain a comfortable fitness level. Your progress through these stages should be gradual and comfortable. You shouldn't hobble home after your first workout and be sore for days -- that's a good way to get injured and become discouraged. Instead, start at the right level, and then push yourself harder over time as your body becomes stronger. Exercise Article Index >> News I Health I Wellness I Exercise I Profiles I Business I Links I Women ROCK! Product Review I To the Point I Contact I Home Created by: Art Street Design Studio. © Concerning Women Communications, Inc. all rights reserved.