Exercise within this zone enhances a body's ability to move oxygen to, and carbon dioxide away, from the muscles being used. During aerobic activity, one may feel some discomfort, but it should not be painful. Further, breathing may be strong and a person may feel exertion on the body.

Training in the fat burning, healthy heart and aerobic zones should lead an individual to an active, healthy lifestyle. The final two zones are used by individuals training for athletic and competitive activities.

Conditioning zone. The conditioning zone is designed to allow individuals to cross over from aerobic to anaerobic training and is intended for vigorously active individuals with performance goals. During this type of activity, the systems providing energy for the activity do not require oxygen. The main benefit of anaerobic training is to increase ability to metabolize lactic acid, thus allowing muscles to train harder before experiencing the pain of lactate accumulation.

The intensity of anaerobic training is hard and individuals who engage in this type of activity will experience tired muscles, heavy breathing and fatigue. Anaerobic exercise is generally used if one is training for competition and should not be used by the untrained or unconditioned. A day of anaerobic activity should be followed by a day of fat burning or healthy heart training to let the body recover.

Red zone. The top level of the adult activity pyramid should be used only by those individuals who are extremely fit. With this type of training, one crosses the anaerobic threshold and is working in oxygen debt. The training is extremely difficult and will result in a feeling that one cannot breathe fast enough to keep up with the demand for oxygen.

This level of activity is typically used by individuals training for serious competition. For untrained or unprepared individuals, these workouts will result in great discomfort and maybe even injury. Red zone activities should only be performed once a week and should be followed by healthy heart or fat burning exercises. Due to the intensity of red zone activities, participation in this zone for more than two days in a row may result in acute injuries.

Caloric expenditure

As mentioned earlier, the Surgeon General's Report suggests that all individuals burn 150 calories of energy per day or 1,000 calories per week through physical activity. This provides a new challenge for personal trainers who, for many years, have used heart rate intensity as the measure of fitness training. In response to this, we present a companion piece to the adult activity pyramid -- the time and calorie chart for physical activity (TCCPA). This chart is designed for individuals who prefer to focus on caloric expenditure rather than heart rate intensity in their training.

Figure 2 is an example of a TCCPA for a 110-pound person. (Charts are also available for 130-, 150- and 170-pound individuals.) Across the top of the chart are numbers indicating minutes of duration from five minutes to one hour. Down the right side of the chart is a listing of various popular physical activities. The top of the chart includes aerobic activities that are vigorously intense. The middle includes healthy heart activities that fluctuate between vigorous and moderate intensity. And the bottom of the chart includes fat-burning activities that are moderately intense and can be performed by almost anyone for an extended period.

The numbers within the chart provide an approximate value of calories expended in a particular activity for a particular period of time. For example, if a 110-pound person plays competitive tennis for 20 minutes, he or she will expend approximately 140 calories. The number of calories for each activity by time were determined using a standard formula for determining caloric expenditure as described by McArdle, Katch and Katch in Exercise Physiology, Energy Nutrition and Human Performance.3 All numbers have been rounded off to enhance readability of the chart. The chart has been divided into three separate zones, each with distinct health and fitness benefits.

Combination zone. The standard for determining the combination zone was based on the Surgeon General's recommendation. The line indicating this standard travels down the chart at the 150-calorie level. Expending 150 calories per day in physical activity helps one maintain a degree of health, albeit a minimal level. For many Americans who have been physically inactive, however, this may be the place to start to become healthy.

It is important to note that any one physical activity performed for the amount of time as indicated in the combination zone may not provide the health benefits one desires. If an individual does not engage in the activity long enough to expend 150 calories, he or she will need to do a combination of these activities to achieve the standard. For example, one could expend 85 calories by raking leaves for 20 minutes and then expend 85 calories mowing the yard for 10 minutes. The two activities combined will burn 170 calories in physical activity.

Health improvement zone. The health improvement zone falls between the Surgeon General's standard and a standard based on research conducted by Paffenbarger.4 Paffenbarger's findings indicated that the greatest decrease in cardiovascular deaths was observed among individuals who expended in excess of 2,000 calories per week in physical activity.

Expending between 150 to 300 calories in physical activity per day maintains and improves health. If individuals engage in any physical activity long enough to expend enough calories to place them into this zone, they can feel some assurance they are not only maintaining, but actually improving their health.

Longevity zone. The longevity zone is also based on Paffenbarger's work. In his studies, he reported that the risk of death from all causes became progressively lower as physical activity levels increased to about 3,500 calories per week. Expending more than 3,500 calories per week did not seem to reduce relative risk any further. Burning between 300 to 500 calories in physical activity per day enables a person to reduce his or her risk of premature death from cardiovascular disease.

Although expending calories in excess of 500 per day in physical activity does not significantly improve chances for decreased mortality, it still has benefits. For example, individuals training for sports must exercise at a level appropriate for their activity, and individuals attempting to lose weight may want to exercise for longer periods to lose more weight.

So how much is enough?

Health benefits appear to be proportional to the amount of activity, rather than to the intensity of the exercise. If health maintenance is the goal, the Surgeon General suggests a minimum of 150 calories expended per day in physical activity. To improve health, Paffenbarger suggests expending between 150 and 300 calories per day, and to increase longevity, he suggests expending between 300 and 500 calories per day. If fitness is the goal, the amount of calories expended depends on the goals of the individual. Competition in sports will require still higher caloric expenditure, with a different exercise prescription than the former types.

Improving the health of the American public is a tremendous responsibility. Having tools like the ones described here can help personal trainers and health promotion specialists improve the health of their clients. The research is clear: Doing something is better than nothing, and that "something" does not need to be intensive. The goals of the client need to be addressed before the exercise prescription is decided, and the adult education pyramid and time and calorie chart for physical activity can help formulate these plans.

Activity Habits and Patterns of American Adults

* Inactivity and poor diet cause as least 300,000 deaths a year in the United States.
* Adults who are less active are at greater risk of dying of heart disease and developing diabetes, colon cancer and high blood pressure.
* More than 60 percent of U.S. adults do not engage in the recommended amount of activity.
* Approximately 25 percent of U.S. adults are not active at all.
* Physical inactivity is more common among women than men, African American and Hispanic adults than whites, older than younger adults, and the less affluent than more affluent individuals.
* Social support from family and friends is consistently and positively related to regular physical activity.
* Inactivity increases with age. By age 75, about one in three men and one in two women engage in no physical activity.
* People with disabilities are less likely to engage in regular moderate physical activity than people without disabilities, yet they have similar needs to promote health and prevent lifestyle-related disease.

By Donna J. Terbizan & Brad Strand.

REFERENCES

Edwards, S. The Heart Rate Monitor Book. Sacramento, CA: Fleet Feet Press, 1993.
Franks, B.D. Personalizing physical activity prescription. The President's Council on Physical Fitness and Sports Research Digest. 2(9), 1997.
McArdle, W.D., & F.I. & V.L. Katch. Exercise Physiology, Energy, Nutrition and Human Performance, 3rd. ed. Appendix D: Energy expenditure in household, recreational, and sports activities. Philadelphia: Lea & Febiger, 1991.
Paffenbarger, R.S., R.T. Hyde, A.L. Wing, & C.H. Steinmetz. A natural history of athleticism and cardiovascular health. Journal of American Medical Association. 252:491-495, 1984.
Pate, R., M. Pratt, S. Blair, et al. Physical activity and public health. Journal of the American Medical Association. 273(5):402-407, 1995.
U.S. Department of Health and Human Services. Physical Activity and Health: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, 1996.

 

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