Physical Activity Health Article

THE PHYSICAL ACTIVITY PYRAMID

The 2000 exercise and prescription guidelines of the ACSM acknowledged the new strategy of physical activity for health. The FIT (frequency, intensity, time or duration) formula for various types of physical activity was adjusted to include more moderate activity that results in specific health benefits. The Physical Activity Pyramid (see Figure1) illustrates the FIT formula for six different types of physical activity, each with its own unique benefits. The Physical Activity Pyramid is modeled after the Food Guide Pyramid developed by the United States Department of Agriculture.

At the base of the pyramid (Level 1) is lifestyle physical activity. Lifestyle physical activities are those people can do as part of their regular workday or daily routine. Examples of such activities are yard work and delivering the mail. A person who works while sitting at a desk for most of the day can get lifestyle activity by walking or riding a bicycle to work rather than driving a car, or by walking up the stairs at work rather than taking an elevator. Those who are totally sedentary should focus on this level of the pyramid because moderate amounts of physical activity can provide many of the health benefits outlined in Figure 1. As the 1996 Surgeon General's Report states, "something is better than nothing," and a good start would be thirty minutes of lifestyle physical activity on most days of the week.

Level 2 of the pyramid includes active aerobic activities. Aerobic activities are those performed at a pace for which the body can supply adequate oxygen to meet the demands of the activity. Because lifestyle activities meet this criterion, they are aerobic in nature. In the pyramid, however, active aerobics refers to those aerobic activities that elevate the heart rate to an appropriate target heart rate. This level includes aerobic activities using the FIT formula based on target heart rate (elevating the heart rate to an appropriate intensity at least three days a week for a time of at least 20 minutes). Examples of popular moderate to vigorous active aerobics are aerobic dance, step aerobics, jogging, moderate to vigorous swimming, and biking. Because they are more vigorous than activities at Level 1, active aerobics can be performed less frequently and the time of each activity bout can be shorter.

Also on Level 2 of the pyramid are active sports and recreational activities. Some examples of active sports are basketball, tennis, hiking, racquetball, and volleyball. Like active aerobics, this type of activity is typically more vigorous than lifestyle physical activity. Sports involve vigorous bursts of activity with brief rest periods. Though they are often not truly aerobic in nature, when they are done without long rest periods they have many of the same benefits as aerobic activities. The FIT formula for active sports and recreation is similar to the formula for active aerobics.

Some sports are not vigorously active and should be considered lifestyle physical activities. For example, golf, as a physical activity, is similar to walking to work, rather than the more vigorous activity generated in tennis or basketball—it is beneficial, but not vigorous in nature. Recreational activities such as rock climbing or canoeing are not considered to be sports by some people. Nevertheless, they can be used to meet the three-day moderate to vigorous recommendation for active sports if performed vigorously. Recreational

Figure 1

activities such as fishing and chess are not considered to be in this category. These activities have benefits, but are not in the moderate to vigorous physical activity category.

Flexibility exercises are included at Level 3 of the pyramid. These are referred to as exercises because they are done specifically to build the part of physical fitness called flexibility. Flexibility is the ability to use joints through a full range of motion as a result of having long muscles and elastic connective tissues. There are, no doubt, some activities from the first two levels of the pyramid that help build flexibility to some extent. Still, to develop this part of fitness, it is necessary to do special flexibility exercises that involve stretching the muscles and using the joints through their full range of normal motion. For this purpose stretching exercises are best.

Flexibility exercises should be done at least three days a week, and as often as every day. The intensity requires stretching beyond normal to a point of mild discomfort. Each exercise is performed several times for 15 to 30 seconds. It is important to perform exercises for each of the body's major muscle groups.

Muscle fitness includes strength and muscular endurance. Exercises to develop muscle fitness are included at Level 3 of the pyramid. Some of the activities from the first two levels of the pyramid can contribute to the development of muscle fitness. But most experts agree that if you want to improve muscle fitness you need to do some exercises especially designed to build it.

The ACSM recommends that muscle fitness exercises be done at least twice a week. Exercises for several different muscle groups (between 8 and 10) should be done using a percentage of the maximum weight a person can lift. The percentage (intensity) depends on the type of muscle fitness to be developed. Each exercise should be performed 8 to 12 times (a set). More frequent training and additional sets or combinations of sets and repetitions produce larger strength gains, but the additional improvement is relatively small.

At the top of the pyramid is inactivity (Level4). Some inactivity is not necessarily bad. For example, we need adequate amounts of sleep, and after vigorous exercise rest is important. Also, there are benefits associated with activities that are fairly sedentary. Fishing can be a relaxing experience that helps people get away from the stress of daily living. Nevertheless, the Physical Activity Pyramid is meant to provide information about the benefits of regular physical activity. Sedentary living as a lifestyle is discouraged. Long periods of inactivity during the hours of the day when you are awake should be limited. People who only sit and watch television or who spend all of their free time playing video games are not getting the activity they need for good health.

Ideally, a person should do some regular physical activity from each of the first three levels of the pyramid each week. However, if doing activity at all three levels proves discouraging or seems to be too difficult, it is better to select activities from fewer categories, beginning with the bottom of the pyramid.