Trying to lose weight without increasing your level of physical activity is like driving a car with no gas in the tank. You may roll forward a little, but you're not really going to get anywhere. One pound equals 3,500 calories. So to lose a pound in, say a week, you'll either have to eat 3,500 calories less or burn off 3,500 calories in exercise, or some combination of the two. Some combination of the two is easier and healthier in the long run.
Exercise burns calories. While the specific rate at which calories are burned depends on individual weight and the intensity of the activity, here are some examples of calorie-burning activities. Walking briskly can burn off about 100 calories per mile. Bicycling for a half hour at nearly 10 miles per hour will burn about 195 calories. Experts recommend at least 30 minutes of vigorous activity five days a week. If you can't find 30 minutes, try two 15-minute intervals, or even three 10-minute intervals. And realize that what's vigorous for a sedentary person is different from a vigorous workout for an athlete. Work at your own pace.
To assist Americans and to encourage daily exercise and personal fitness, the U.S. Department of Health and Human Services (HHS) in 2008 issued a guide, the Physical Activity Guidelines for Americans, available at www.health.gov/paguide lines/. The agency created a comprehensive list of recommendations broken into various age categories aimed at helping people include physical activity into their daily schedule. According to the HHS, the guidelines are based on scientific research about health and exercise. A 13-member advisory committee appointed by then HHS secretary Mike Leavitt provided a thorough review of the literature.
Important recommendations from the guidelines for children and adolescents suggest one hour or more of moderate or vigorous aerobic activity each day. Examples of moderate activities are skateboarding, bicycling, and brisk walking. More vigorous activities include sports such as soccer and basketball or jumping rope or running. They also recommended muscle-strengthening activities such as rope climbing or sit-ups three days each week.
Recommendations for adults called for two and a half hours per week of moderate aerobic exercise or one hour and 15 minutes of vigorous activity. Examples of moderate activity include a brisk walk, water aerobics, or yoga. More vigorous activities might include step aerobics, jogging or running, or circuit weight training. The guidelines also suggested that short bouts of physical activity, about 10 minutes, will help many Americans reach their daily physical activity goal. Other suggestions include mixing it up by combining moderate and vigorous physical activities.
The guidelines encourage older adults to follow the guidelines for adults if they have the physical capacity, and those with disabilities should engage in activities that match their abilities in order to avoid inactivity. The American College of Sports Medicine (ACSM) continues to update its physical activity recommendations. Although its basic recommendations remain unchanged from the earlier Physical Activity Pyramid in 1998, the update clarifies exercise duration and intensity. The Physical Activity Pyramid, when introduced, was similar in design to the United States Department of Agriculture's nutritional pyramid, with activities that should be performed the most at the base and less vigorous, less frequent activity at the top.
The ACSM recommendations still call for the bottom level or “everyday activities”—walking, housework or yardwork, outdoor play, walking the dog—to total 30 minutes five days of the week.
The more vigorous activities include active aerobics, sports, and recreation, which should be done at least three times a week for 20 minutes. These vigorous activities, which involve speeding up the heart rate, include basketball, tennis, bicycling, soccer, jumping rope, and hiking. Because these activities elevate the heart rate, three 20-minute intervals per week have about the same health benefits as the activities done every day.
The updated ACSM recommendations also suggest muscle fitness exercises, which should be done two or three times a week. These activities include stretching, light weight lifting, push-ups, curl-ups, and gymnastics. The ACSM recommends that people exercise each major muscle group three to seven days per week and stretch to the point of mild discomfort, but not pain. For strength, the ACSM recommends doing muscle fitness exercises for each major muscle group two or three days a week with a day of rest in between.
The top level of the pyramid is inactivity. In the nutritional pyramid, fats and sugars are at this level—some are required, but they shouldn't be the mainstay of one's diet. Likewise in the activity pyramid, inactivity should be the exception, not the rule. Inactivity should be a small portion of your day—and no more than 30 minutes at a time.
See also Aerobic Exercise; Anaerobic Exercise; Calories; U.S. Department of Health and Human Services (HHS); Walking; Weight Training.
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