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Compendium of Physical Activities: an update of activity codes and MET intensities

AINSWORTH, BARBARA E.; HASKELL, WILLIAM L.; WHITT, MELICIA C.; IRWIN, MELINDA L.; SWARTZ, ANN M.; STRATH, SCOTT J.; O’BRIEN, WILLIAM L.; BASSETT, DAVID R. JR.; SCHMITZ, KATHRYN H.; EMPLAINCOURT, PATRICIA O.; JACOBS, DAVID R. JR.; LEON, ARTHUR S.

Medicine & Science in Sports & Exercise: September 2000 - Volume 32 - Issue 9 - p S498-S516
Measurement of Moderate Physical Activity: Advances in Assessment Techniques

AINSWORTH, B. E,., W. L. HASKELL, M. C. WHITT, M. L. IRWIN, A. M. SWARTZ, S .J. STRATH, W. L. O’BRIEN, D. R. BASSETT, JR., K. H. SCHMITZ, P. O EMPLAINCOURT, D. R. JACOBS, JR., and A. S. LEON. Compendium of physical activities: an update of activity codes and MET intensities. Med. Sci. Sports Exerc., Vol. 32, No. 9, Suppl., pp. S498–S516, 2000. We provide an updated version of the Compendium of Physical Activities, a coding scheme that classifies specific physical activity (PA) by rate of energy expenditure. It was developed to enhance the comparability of results across studies using self-reports of PA. The Compendium coding scheme links a five-digit code that describes physical activities by major headings (e.g., occupation, transportation, etc.) and specific activities within each major heading with its intensity, defined as the ratio of work metabolic rate to a standard resting metabolic rate (MET). Energy expenditure in MET-minutes, MET-hours, kcal, or kcal per kilogram body weight can be estimated for specific activities by type or MET intensity. Additions to the Compendium were obtained from studies describing daily PA patterns of adults and studies measuring the energy cost of specific physical activities in field settings. The updated version includes two new major headings of volunteer and religious activities, extends the number of specific activities from 477 to 605, and provides updated MET intensity levels for selected activities.

Department of Epidemiology and Biostatistics, Department of Exercise Science, School of Public Health, University of South Carolina, Columbia, SC 29208; Stanford Center for Research in Disease Prevention, School of Medicine, Stanford University, Palo Alto, CA 94304; Division of Kinesiology, School of Kinesiology and Leisure Studies, University of Minnesota, Minneapolis, MN 55454; Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, MN 55455; Department of Exercise Science and Sport Management, University of Tennessee, Knoxville, TN 37996; Department of Human Performance, University of Alabama, Tuscaloosa, AL 35487

Address for correspondence: Barbara E. Ainsworth, Ph.D., MPH, FACSM, Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC 29208; E-mail: bainsworth@sph.sc.edu.

The Compendium of Physical Activities was developed to facilitate the coding of physical activities (PAs) obtained from PA records, logs, and surveys and to promote comparison of coded physical activity intensity levels across observational studies (1). The Compendium provides a coding scheme that links a five-digit code, representing the specific activities performed in various settings, with their respective metabolic equivalent (MET) intensity levels. Using the definition for a MET as the ratio of work metabolic rate to a standard resting metabolic rate of 1.0 (4.184 kJ)·kg1·h1, 1 MET is considered a resting metabolic rate obtained during quiet sitting. Activities are listed in the Compendium as multiples of the resting MET level and range from 0.9 (sleeping) to 18 METs (running at 10.9 mph).

We provide an update of the initial Compendium of Physical Activities, developed in 1989 and published in 1993. The updated Compendium reflects additional activities identified by researchers in the past 10 years and presents measured MET intensities for some activities in which METs were estimated from similar activities. The updated Compendium also reflects public health interests in evaluating the contributions of various types of physical activity to daily energy expenditure by providing additional categories for activities done during the day.

The initial Compendium has received widespread acceptance among PA specialists in the exercise science and public health fields. For example, in the United States, the coding scheme has been used to identify MET intensities for PAs in the third National Health and Nutrition Examination Survey (6), the 1991 National Health Interview Survey (11), the Paffenbarger College Alumni Study (15), and to evaluate the accuracy of the Minnesota Leisure Time Physical Activity Questionnaire (MN-LTPA) (26). Internationally, the Compendium has been used to identify MET intensities for activities listed in the MONICA Optional Survey of Physical Activity (MOSPA) (12). The coding scheme and MET intensities for activities listed in the Compendium of Physical Activities also have been published as an appendix or abstracted as a chart in several books (18–20,34).

In their landmark 1995 paper that presents the recommendation of the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) for adults to accumulate at least 30 min of regular, moderate-intensity physical activity on most days of the week, Pate et al. (23) cite the Compendium as a reference that researchers, clinicians, and practitioners can use to identify examples of moderate intensity physical activities.

The updated Compendium includes two additional major headings and 129 new specific activities. It also provides modifications of 94 codes in the 1993 Compendium, adding or deleting specific activities or providing updated MET levels. The new major headings and most of the specific activities were identified from studies using PA records to identify daily PA habits among adults (2,3) and from personal communications from other investigators who reported activities omitted from the initial Compendium. Updated MET levels were obtained from laboratory and field studies designed to measure the energy cost for specific PAs (4,7–9,16,17,21,22,24,27–30,32,35,37). We have also clarified the meaning of the letter T followed by three numbers (i.e., T010) as activities and their associated MET levels defined by Dr. Henry Taylor for the MN-LTPA (31). The letter T is now replaced by the words Taylor Code and followed by the MN-LTPA survey item number (e.g., Taylor Code 010). In this paper we present the updated Compendium of Physical Activities (Appendix 1) and recommendations for its implementation to identify PA habits using PA records.

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CODING SCHEME

Activity coding.

The reader is referred to the 1993 published version of the Compendium (1) for a detailed description of the coding scheme, organization, and methods used to calculate the energy cost of PAs. Briefly, the Compendium is organized to maximize flexibility in coding, data entry, and interpretation of energy cost for each class and type of PA. The coding scheme employs a five-digit code to categorize activities by their major purpose or heading (first two digits), specific activity (last three digits), and intensity (separate two- or three-digit column). For example, the five-digit code, 06100, is defined as follows:MATH

CV

CV

Based on the model proposed by Pate et al. (23) for classifying the MET intensity of PAs (light, < 3 METs; moderate, 3–6 METs; vigorous, > 6 METs), the activity code 06100 is classified as moderate intensity.

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Major headings.

Two additional major headings were added to the updated Compendium of Physical Activities for a total of 21 major types of PAs (Table 1).

Table 1

Table 1

The two new categories, religious activities and volunteer activities, were identified from the use of PA records in the Cross-Cultural Activity Participation Study (CAPS) (2). CAPS was an observational study of PA habits among African American, Native American, and Caucasian women, ages 40 yr and older. The new categories include 43 specific activities that are culturally and socially relevant among ethnic minorities and/or older adults. Religious and ceremonial activities play a central role in the lives of many older adults, especially among ethnic minority groups (5). Among retired people and others not employed in occupational settings, volunteer activities also commonly represent an important contribution to daily energy expenditure.

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Specific activities.

The updated Compendium contains 605 specific activities, including 129 new activities added to the 1993 Compendium. Modifications were also made to 94 PAs listed in the 1993 Compendium, which involved adding or deleting specific activities associated with each code. For example, for the code 08030, lawn and garden activities, the phrase “wheelbarrow chores” was added to the 1993 Compendium’s specifications of clearing land and hauling branches. In other cases, activities were removed from existing codes and new codes were developed if the removed activities had a different MET level or were qualitatively different from other specific activities listed for the code. For example, the 1993 Compendium listed mopping as a specific activity in code 05020, home activities. However, Emplaincourt (7) measured the MET intensity for mopping as 3.5 METs and the MET intensity for the other activities in the code was listed as 3.0 METs. Thus, mopping was deleted from code 05020 and a new code, 05021, was created. Another example is watching television. In 1993, watching television was coded as 07010 (reclining) or 07020 (sitting) and was grouped with other specific activities that involved sitting quietly (i.e., riding in a car, listening to a lecture or to music) or reclining and doing nothing. Because watching television is a sedentary but modifiable leisure time activity that may be related to the increased prevalence of physical inactivity (36), overweight, and obesity in the United States (13,14), the authors felt that watching television should have a separate code to monitor time spent in this activity. In the updated Compendium, the codes 07010 and 07020 refer to watching television only. New codes have been added for the remaining inactive reclining (07011) and sitting (07021) activities. Table 2 presents the new five-digit codes, and Table 3 presents the modifications for existing codes as incorporated in the updated Compendium.

Table 2

Table 2

Table 3

Table 3

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Intensity of activities.

All activities are assigned an intensity level based on the rate of energy expenditure expressed as METs. Intensity of activities in the Compendium is classified as multiples of 1 MET or as the ratio of the associated metabolic rate for the specific activity divided by a standard RMR. In the 1993 Compendium, MET values were assigned to each activity based on the “best representation“ of an intensity level from published lists and selected unpublished data (1). For activities not in original lists or in other unpublished reports of the energy cost of physical activities, data were obtained from published literature and assigned a measured MET value or was estimated from similar activities with a known MET value (1).

MET levels for 42 activities in the updated Compendium were changed based on published and unpublished studies that measured the energy cost of PAs (4,7–9,16,17,21,22,24,27–30,32,35,37). Since the publication of the 1995 Pate et al. (23) moderate activity recommendation, there has been widespread interest among health educators, clinicians, public health specialists, and fitness professionals to recommend types of activities that are classified as moderate intensity. There was some concern, however, that the MET levels for many household, lawn and garden, walking, and some occupational activities frequently performed by older adults, people of color, and women of all ages had not been objectively measured, but had been assigned estimated MET intensities. Thus, in 1997–1998, a series of studies were funded by the International Life Sciences Institute Research Foundation to measure the energy cost of selected household, lawn and garden, walking, recreational, and occupational activities using indirect calorimetry methods in laboratory and field settings (4,9,29,30,35). Doctoral dissertations and other research studies have also focused on measuring the MET intensities of household, lawn and garden, cultural, and custodial activities (8,9,27,28).

Because changes in MET intensities for selected activities may change the energy cost of PA, investigators using the 1993 Compendium in cohort studies may wish to continue using the 1993 Compendium to compute the energy cost of activities. However, for newer activities, codes in the 2000 Compendium are appropriate for use.

As in the 1993 Compendium of Physical Activities, the updated Compendium provides data for adults without handicaps or other conditions that would significantly alter their mechanical or metabolic efficiency. Also, a study is underway at the University of North Carolina at Chapel Hill to measure the energy cost of individual and group PAs among youth, ages 8–18 yr (J. A. Harrell, School of Nursing, University of North Carolina at Chapel Hill, 1999). Another study is underway at the Edward Hines Jr. VA Hospital to measure the energy costs of physical activities in adults with spinal cord injuries (W. E. Langbein and E. Collins, Hine Hospital, Maywood, IL, 1999). When completed, the projects will provide compendiums of the PAs measured in the studies.

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Calculation of energy cost.

Methods used to calculate the energy cost of activities in the 1993 Compendium were explained in detail by Ainsworth et al. (1). There has been concern that the absolute MET intensities presented in the Compendium may be inaccurate for people of different body mass and body fat percentage (10,27). For weight-bearing activities, Schmitz et al. (27) and Howell et al. (10) showed that the energy cost of activity was higher among heavier individuals than indicated by the Compendium’s MET intensities. For these individuals, use of the MET intensities in the Compendium would underestimate the actual energy cost of weight bearing activity. The opposite pattern would be observed for non–weight-bearing activities. Schmitz (27) discusses these concerns in relation to energy expended during household chores among obese and lean women. Similar observations may apply to individuals who differ in age, cardiorespiratory fitness levels, and mechanical efficiency and when activities are performed in varied geographic and environmental conditions (33). It should be emphasized that the Compendium was developed to facilitate the coding of PAs and to compare coding across studies. It does not take into account individual differences that may alter the energy cost of movement. Thus, a correction factor may be needed to adjust for individual differences when estimating the energy cost of PA in individuals; but no such general correction is available at this time.

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Use of the Compendium in PA validation studies.

The Compendium facilitates the use of PA records to record the type, intensity, and duration of activities in a systematic manner. PA records and the Compendium have been used to validate PA surveys commonly used in observational and clinical studies (25). In 1993, we presented a sample PA record for use with the Compendium (1). We have since developed an updated PA record that is easy to use and code and provides a detailed explanation for the use of PA records and the Compendium in PA validation studies.

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DISCUSSION AND LIMITATIONS

The value and limitations of using the Compendium of Physical Activities to determine the energy cost of PA in adults was previously discussed in the 1993 publication (1). Because the MET levels presented in the Compendium are based on the energy cost of actual movement, investigators should remind participants to recall only the time spent in movement when using the Compendium to estimate the energy cost of activities. It should also be stressed that the Compendium was not developed to determine the precise energy cost of PA within individuals, but instead to provide an activity classification system that standardizes the MET intensities of PAs used in survey research. This limits the use of the Compendium in estimating the energy cost of PA in individuals in ways that account for differences in body mass, adiposity, age, sex, efficiency of movement, geographic and environmental conditions in which the activities are performed. Thus, individual differences in energy expenditure for the same activity can be large and the true energy cost for a person may or may not be close to the stated mean MET level as presented in the Compendium.

As was true with the original Compendium, the updated version contains specific activities in which the MET values were not derived from indirect calorimetry; however, many codes have been updated using measured MET values. The updated Compendium still has some codes in which MET values were estimated from activities having similarmovement patterns. Therefore, these estimates may have ill-defined confidence limits around the mean MET values.

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SUMMARY

The updated version of the 1993 Compendium of Physical Activities includes new major headings for religious and volunteer activities, new five-digit codes for 129 specific activities, and modifications to codes for 94 specific activities. Despite its known limitations, the Compendium has proven useful in coding physical activity surveys or records and in providing examples of activities within broad intensity ranges for use for PA counseling in research, education, and clinic settings. However, additional methods are needed to account for differences in individual characteristics that may alter the energy costs of physical activities.

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NOTES

An unpublished edition of the Compendium was developed in 2000 to track changes from the first edition and to explore possible changes in future editions. The unpublished edition includes a two-digit number that identifies the version of the Compendium. The version number should make it simple to make corrections and additions to activity codes and their intensities while retaining the ability to code questionnaires consistently with questionnaires collected earlier on the same person. A copy of the unpublished tracking version of the Compendium may be obtained from Dr. Barbara Ainsworth.

Many people participated in the identification of specific activities and the modification of existing codes for the updated Compendium of Physical Activities. Although the individuals involved are too numerous to mention, we wish to thank a few colleagues and graduate students (listed by their institutional affiliation) for their valuable contributions to the updated Compendium of Physical Activities.

Th e individuals are listed by their institutional affiliation: Jennifer Hootman and Angela Morgan (University of South Carolina), Mark Richardson (University of Alabama), Devra Hendelman and Patty Freedson (University of Massachusetts), Gregory Welk (Iowa State University), Steven Blair (Cooper Institute for Aerobics Research), Vivian Heyward, Lisa Stolarczyk, and Julia Orri (University of New Mexico), and Ava Walker (University of Minnesota).

This work was supported in part by the International Life Sciences Institute Center for Health Promotion (ILSI CHP). The use of trade names and commercial sources in this document is for purposes of identification only and does not imply endorsement by ILSI CHP. In addition, the views expressed herein are those of the individual authors and/or their organizations and do not necessarily reflect those of ILSI CHP.

Dr. Leon is supported in part by the Henry L. Taylor Professorship in Exercise Science and Health Enhancement. Dr. Ainsworth is supported in part by the NIH Women’s Health Initiative SIP 22W-U48/CCU 409554–03.

Support for the development of the initial Compendium of Physical Activities was provided by grants from the National Heart, Lung, and Blood Institute to Drs. Leon and Jacobs (RFA-86–37561), to Dr. Haskell (HL-362–72),to Dr. Montoye (5-R01-HL-37561), and to Dr. James Sallis (RFA-86-HL-9-P).

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REFERENCES

1. Ainsworth, B. E., W. L. Haskell, A. S. Leon, et al. Compendium of physical activities: energy costs of human movement. Med. Sci. Sports Exerc. 25: 71–80, 1993.
2. Ainsworth, B. E., M. L. Irwin, C. L. Addy, M. C. Whitt, and L. M. Stolarczyk. Moderate physical activity patterns among minority women: the Cross-Cultural Activity Participation Study. J. Women’s Health 8: 805–813, 1999.
3. Ainsworth, B. E., B. Sternfeld, M. T. Richardson, and K. Jackson. Evaluation of the Kaiser Physical Activity Survey in Women. Med. Sci. Sports Exerc. 32(Suppl.), 2000.
4. Bassett, D. R. Jr., B. E. Ainsworth, A. M. Swartz, S. J. Strath, W. L. O’Brien,and G. A. King. Validity of four motion sensors in measuring moderate intensity physical activity. Med. Sci. Sports Exerc. 32: (Suppl.) S471–S480, 2000.
5. Bayne-Smith, M. Race, Gender, and Health. Thousand Oaks, CA: Sage Publications, 1996, p. 134.
6. Crespo, C. J., S. J. Keteyian, G. W. Heath, and C. T. Sempos. Leisure-time physical activity among US adults: results from the Third National Health and Nutrition Examination Survey. Arch. Intern. Med. 156: 93–98, 1996.
7. Emplaincourt, P. O. Inter-individual Variability in the Energy Cost of Several Habitual Physical Activities. Unpublished Ph. D. Dissertation, University of Alabama, Tuscaloosa, AL, 1999.
8. Gilman, M. B., H. Houle, L. Firzell, K. Headbird, J. L. Durstine, and B. E. Ainsworth. Metabolic cost of traditional American Indian activities in women over 40 years of age (Abstract). Med. Sci. Sports Exerc. 32: S53, 2000.
9. Hendelman, D., K. Miller, C. Bagget, E. Debold, and P. Freedson. Validity of accelerometry for the assessment of moderate intensity physical activity in the field. Med. Sci. Sports Exerc. 32: (Suppl.) S442–S449, 2000.
10. Howell, W., C. Earthman, P. Reid, J. Delaney, and L. Houtkooper. Doubly labeled water validation of the Compendium of Physical Activities in lean and obese college women (Abstract). Med. Sci. Sports Exerc. 31: S142, 1999.
11. Jones, D. A., B. E. Ainsworth, J. B. Croft, J. R. Livengood, E. Lloyd, and H. R. Yusuf. Prevalences of moderate physical activity recommended by the Surgeon General’s Report in U.S. adults: National Health Interview Survey, 1990. Arch. Family Med. 7: 285–289, 1998.
12. Jones, D. A., C. D. Kimsey, C. A. Macera, and C. M. Fuchs. Characteristics of physical activity among employed adults in selected WHO MONICA sites (Abstract). Med. Sci. Sports Exerc. 32: S187, 2000.
13. Kuczmarski, R. J., M. D. Carroll, K. M. Flegal, and R. P. Troiano. Varying body mass index cutoff points to describe overweight prevalence among U.S. adults: NHANES III (1988–1994). Obes. Res. 5: 542–548, 1997.
14. Kuczmarski, R. J., K. M. Flegal, S. M. Campbell, and C. L. Johnson. Increasing prevalence of overweight among U.S. adults: the National Health and Nutrition Examination Surveys 1960–1991. JAMA 272: 205–211, 1994.
15. Lee, I-M., C-C. Hsieh, and R. S. Paffenbarger,Jr. Exercise intensity and longevity in men. JAMA 273: 1179–1184, 1995.
16. Margaria, R., P. Cerretelli, P. Aghemo, and G. Sassi. Energy cost of running. J. Appl. Physiol. 18: 367–370, 1963.
17. Melanson, E. L., P. S. Freedson, R. Webb, S. Jungbluth, and N. Kozlowski. Exercise responses to running and in-line skating at self-selected paces. Med. Sci. Sports Exerc. 28: 247–250, 1996.
18. Montoye, H. J. The energy cost of exercise and competitive sport. In:Nutrition in Sport: Olympic Encyclopaedia of Sports Medicine, Vol. VII, R. J. Maughan (Ed.). Maldea, MA: Blackwell Science Inc., 2000, pp. 53–72.
19. Montoye, H. J., H. C. G. Kemper, W. H. M. Saris, and R. A. Washburn. Measuring Physical Activity and Energy Expenditure. Champaign, IL: Human Kinetics Publishers, 1996, pp. 34–41.
20. Nieman, D. C. Fitness and Sports Medicine, 2nd Ed. Palo Alto: Bull Publishing Co., 1995, pp. 685–691.
21. Noble R. M., and E. T. Howley. The energy requirement of selected tap dance routines. Res. Q. 50: 438–442, 1979.
22. Olson M. S., H. N. Williford, D. L. Blessing, and R. Greathouse. The cardiovascular and metabolic effect of bench stepping exercise stepping in females. Med. Sci. Sports Exerc. 23: 1311–1318, 1991.
23. Pate, R. R., M. Pratt, S. N. Blair, et al. Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 273: 402–407, 1995.
24. Patterson R., and S. V. Fisher. Cardiovascular stress of crutch walking. Arch. Phys. Med. Rehabil. 62: 257–260, 1981.
25. Pereira, M. A., S. J. Fitzgerald, E. W., and Gregg, et al. A collection of physical activity questionnaires for health related research. Med. Sci. Sports Exerc. 29:S1–S205, 1997.
26. Richardson, M. T., A. S. Leon, D. R. Jacobs, Jr., B. E. Ainsworth, and R. C. Serfass. Comprehensive evaluation of the Minnesota Leisure Time Physical Activity Questionnaire. J. Clin. Epidemiol. 47: 271–281, 1994.
27. Schmitz, M. K. H. The Interactive and Independent Associations of Physical Activity, Body Weight, and Blood Lipid Levels. Unpublished Ph. D. Dissertation, University of Minnesota, Minneapolis, MN, 1998.
28. Smith J. F. Energy cost of specific custodial work tasks. Unpublished Doctoral Dissertation, University of Tennessee 1975:.
29. Strath S. J., A. M. Swartz, D. R. Bassett, Jr., W. L. O’Brien, G. A. King, and B. E. Ainsworth. Evaluation of heart rate as a method for estimating moderate intensity physical activity. Med. Sci. Sports Exerc. 32: (Suppl.) S471–S480, 2000.
30. Swartz, A. M., S. J. Strath, D. R. Bassett, Jr., W. L. O’Brien, G. A. King, and B. E. Ainsworth. Estimation of energy expenditure using CSA, Inc. accelerometer hip and wrist sites. Med. Sci. Sports Exerc. 32: (Suppl.) S450–S456, 2000.
31. Taylor H. L., D. R. Jacobs Jr., B. Schuker, J. Knudsen, A. S. Leon, and G. Debacker. A questionnaire for the assessment of leisure time physical activities. J. Chronic Dis. 31: 741–755, 1978.
32. Town G. P., N. Sol, and W. Sinning. The effect of rope skipping rate on energy expenditure of males and females. Med. Sci. Sports Exerc. 12: 295–298, 1980.
33. 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, pp. 29–37.
34. U. S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Human Promotion, Division of Nutrition and Physical Activity. Promoting Physical Activity: A Guide for Community Action. Champaign, IL: Human Kinetics, 1999.
35. Welk, G. J., S. N. Blair, K. Wood, S. Jones, and R. W. Thompson. A comparative evaluation of three accelerometry-based physical activity monitors. Med. Sci. Sports Exerc. 32: (Suppl.) S489–S497, 2000.
36. Williams, C. D., J. F. Sallis, K. J. Calfas, and R. Burke. Psychosocial and demographic correlates of television viewing. Am. J. Health Promot. 13: 207–214, 1999.
37. Zeni A. I., M. D. Hoffman, and P. S. Clifford. Energy expenditure with indoor exercise machines. JAMA 275: 1424–1427, 1996.
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Appendix 1

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Keywords:

EXERCISE; EXERTION; ENERGY EXPENDITURE

© 2000 Lippincott Williams & Wilkins, Inc.