No. 2, April 2005
Prevalence of Physical Activity in the United States:
Behavioral Risk Factor Surveillance System, 2001
Caroline A. Macera, PhD, Sandra A. Ham, MS, Michelle M. Yore,
MSPH, Deborah A. Jones, PhD, Barbara E. Ainsworth, PhD, MPH, C. Dexter Kimsey, PhD, MSEH, Harold W. Kohl III, PhD
Suggested citation for this article: Macera CA, Ham SA,
Yore MM, Jones DA, Ainsworth BE, Kimsey CD, et al. Prevalence of
physical activity in the United States: Behavioral Risk Factor
Surveillance System, 2001. Prev Chronic Dis [serial online] 2005 Apr [date cited]. Available from: URL: http://www.cdc.gov/pcd/issues/2005/
The health benefits of regular cardiovascular exercise are well-known. Such exercise,
however, has traditionally been defined as vigorous physical activity, such
as jogging, swimming, or aerobic dance. Exercise of moderate intensity also
promotes health, and many U.S. adults may be experiencing the health benefits of
exercise through lifestyle activities of moderate intensity, such as yard work,
housework, or walking for transportation. Until recently, public health
surveillance systems have not included assessments of this type of physical
activity, focusing on exercise of vigorous intensity. We used an
enhanced surveillance tool to describe the prevalence and amount of both
moderate-intensity and vigorous-intensity physical activity among
We analyzed data from the 2001 Behavioral Risk Factor
Surveillance System, a state-based, random-digit–dialed telephone
survey administered to U.S. adults aged 18 years and older (n =
82,834 men and 120,286 women). Physical activity behavior was
assessed using questions designed to quantify the frequency of
participation in moderate- or vigorous-intensity physical
activities performed during leisure time or for household chores
Overall, 45% of adults (48% of men and 43% of women) were
active at recommended levels during nonworking hours (at least 30 minutes five
or more days per week in moderate-intensity
activities, equivalent to brisk walking, or at least 20 minutes
three or more days per week in vigorous activities, equivalent to
running, heavy yard work, or aerobic dance). Less than 16% of
adults (15% of men and 17% of women) reported no moderate or
vigorous activity in a usual week.
Integrating surveillance of lifestyle activities into national systems is
possible, and doing so may provide a more accurate representation of the
prevalence of recommended levels of physical activity. These results, however,
suggest that the majority of U.S. adults are not active at levels associated
with the promotion and maintenance of health.
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The 1996 Surgeon General's report on physical activity and health (1) emphasized the health benefits of
moderate-intensity physical activities, especially everyday
activities. These activities include heavy yard work, brisk
walking, and housework in addition to purposeful leisure-time
exercise. Participation in activities of at least moderate
intensity is associated with numerous health benefits, including
lower all-cause mortality, lower cardiovascular mortality,
improved function, and enhanced quality of life. Although
vigorous-intensity activities (such as running and other aerobic
sports) that challenge the cardiovascular system are strongly
related to many positive health outcomes, less than 15% of the
U.S. population is active at that level, and this prevalence did
not change from 1990 to 1998 (2). Several organizations and
agencies have supported health-related recommendations of 30
minutes per day of moderate-intensity physical activities on most
days of the week (3,4), but this level of physical activity has
been difficult to track in the U.S. population.
Historically, surveillance systems for physical activity were
designed to measure leisure-time activities with an emphasis on
participation in vigorous-intensity sports. They did not assess
participation in lifestyle physical activities of moderate
intensity that might be related to household, transportation, or
occupational activities. Therefore, it is not possible with
historical surveillance systems to know how many Americans have
been achieving a level of physical activity to ensure health
benefits through a broader range of physical activities that
occur during nonworking hours. To address this question, we
recently documented the prevalence of physical activity during
nonworking hours for each state in the United States (5). The
purpose of this paper is to extend these findings by describing
the epidemiology of physical activity recommendations during
nonworking hours for U.S. adults.
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The Behavioral Risk Factor Surveillance System (BRFSS) is a
population-based, random-digit–dialed telephone survey
administered to U.S. civilian, noninstitutionalized adults aged
18 years and older in the 50 states and the District of Columbia.
Questions on physical activity have been included in most years
since the survey began in 1984. Between 1997 and 2000, the
Physical Activity and Health Branch at the Centers for Disease
Control and Prevention developed a new set of questions designed
to measure occupational, household, and leisure-time physical
activity with a special emphasis on moderate-intensity
activities. Questions were validated using activity logs and
accelerometers and subsequently modified (6). Additional testing
included cognitive testing in 1998 and 1999 and a pilot test in
four states (Nebraska, Georgia, Hawaii, and Michigan) in 1999.
Questions were modified to reflect changes suggested by the
various tests, and because of space constraints, a subset of the
questions was implemented in the 2001 BRFSS.
The final questionnaire included items about moderate and
vigorous activities that are performed during nonworking hours in
a usual week (5). The questions included the number of days per
week and number of minutes per day. These questions required the
respondent to self-select the intensity of an activity, whereas
in previous BRFSS surveys the participant specified an activity
and standard intensity values were applied according to the
respondent’s age and sex. Both approaches generate useful
measurements, but the self-assessed intensity method was selected
because of the wide individual variation in fitness and energy
expenditure required to perform a particular activity. A table
comparing the questions used in the BRFSS for 2000 and 2001 has
been previously published (5).
In addition to questions on moderate and vigorous activities,
a single item was asked of all employed persons. This item
classified occupational activity as “mostly sitting or
standing,” “mostly walking,” or “mostly
The criteria for determining compliance with health-related
physical activity guidelines were adapted from the Surgeon
General’s report on physical activity and health (1) and
other consensus statements (3,4). Respondents were classified as
meeting recommendations if they reported participation in
moderate-intensity activities on five or more days per week for
30 or more minutes per day and/or vigorous activity for three or
more days per week for 20 minutes or more per day. Respondents
were classified as inactive if they reported no moderate or
vigorous physical activity on any day during a usual week.
In addition to employment activity status, demographic
variables included were age, educational level
(less than high school, high school graduate, some college, and
college graduate), race/ethnicity (non-Hispanic white,
non-Hispanic black, Hispanic, other), body mass index (BMI
calculated as weight [kg]/height [m]2), and region of
the country. BMI was categorized into underweight (<18.5),
healthy weight (18.5–24.9), overweight (25.0–29.9), and obese
(≥30.0). Region of the country was defined as follows:
Midwest (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota,
Missouri, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota,
Wisconsin); Northeast (Connecticut, Maine, Massachusetts, New
Hampshire, New Jersey, New York, Pennsylvania, Rhode Island,
Vermont); South (Alabama, Arkansas, Delaware, District of
Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland,
Mississippi, North Carolina, South Carolina, Tennessee, Texas,
Virginia, West Virginia); and West (Alaska, Arizona, California,
Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon,
Utah, Washington, Wyoming).
All data were stratified by sex, and all prevalence estimates
were age-adjusted to the year 2000 standard population. SUDAAN statistical
software (Research Triangle Institute, Research Triangle Park, NC) was used to
adjust for the complex sample survey design. Logistic regression models were
calculated using “meeting physical activity recommendations” as the outcome.
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After exclusion of 7370 observations from Guam, Puerto Rico,
and the Virgin Islands, the analysis sample included 203,120
respondents (82,834 men and 120,286 women). The median response
rate for all of the states included in the 2001 BRFSS was 51.1%
(7). The method used to calculate the response rate was based on
a formula developed by the Council of American Survey Research
Organizations (CASRO) and reflects the efficiency of telephone
sampling as well as the degree of cooperation among the eligible
respondents contacted (8). Data were weighted by age and sex to
reflect each state’s most recent estimate of the adult
The distributions of age, educational level, occupational
status, and other variables for men and women in the sample are
shown in Table 1. Sixty-four percent of the sample was
aged 30 to 64 years. Eleven percent had less than a high
school education, while 30% had graduated from college. The
distributions of age and education were similar for men and women.
Overall, 38% of the respondents were not currently employed (29%
of men and 43% of women), and 41% of men and women had jobs that
required mostly sitting or standing.
Overall, 45% of the respondents were active at the recommended
levels in their nonworking hours (48% of men and 43% of women)
(Table 2). The prevalence of meeting the criteria for moderate
activity was similar for both men and women (32%), but men
surpassed women in meeting the criteria for vigorous activity
(29% for men vs 20% for women). The data indicate that 13% of
men and 8% of women met the guidelines for both moderate and
vigorous activity, while only 16% of the respondents (15% of men
and 17% of women) were inactive (no moderate or vigorous activity
at any time during a usual week).
As expected, the prevalence of meeting recommended levels of
physical activity was generally lower at older ages. The
difference between the youngest (18 to 29 years) group and oldest (≥75 years)
group in meeting recommendations was slightly greater among
women than men: 50% of women aged 18 to 29 vs 27% of women aged
75 or older, and 58% of men aged 18 to 29 vs 38% for men aged 75
or older. Also as expected, for both men and women, the
prevalence of recommended activity was higher among non-Hispanic
whites than non-Hispanic blacks, Hispanics, or
“other” racial/ethnic groups. Meeting recommended
levels of physical activity was successively higher with greater
educational attainment for both men and women.
The prevalence of recommended physical activity varied by BMI, with about
half the men classified as healthy weight or overweight meeting recommended
levels, while fewer obese or underweight men did so. For women, 50% of those in
the healthy weight group met recommended levels vs only 33% of obese
women. Regional differences were noted; the West had the highest
prevalence of recommended physical activity for both men and
women. As for employment status, women who were active on the job
(mostly walking or heavy labor) were more active during
nonworking hours than those who were less active on the job or
the unemployed. For men, those doing mostly heavy labor were
more active during nonworking hours than other groups.
Odds ratios for meeting recommendations for moderate or
vigorous activity are shown in Table 3 by age, race/ethnicity,
education, BMI, region, and occupational activity. In both sexes,
younger adults (aged 18 to 29) were more active than older
adults, and non-Hispanic whites were more active than the other
racial/ethnic groups. Also, for both men and women, activity was
higher among those with at least a high school education than
among those who did not finish high school. Both the
obese and the underweight groups were less active than the
healthy weight group. In both sexes, those who were active at
work (walking or heavy labor) were more active during nonworking
hours than those who mostly sat or stood at work.
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Because emerging research in the past 15 years has indicated a
dose–response relationship between physical activity and health as
well as the specific health benefits of moderate-intensity
physical activity, surveillance systems must be able to document
prevalence and trends for moderate-intensity lifestyle activity.
The surveillance system for physical activity used in the 2001 BRFSS broadens the concept of physical activity beyond
traditional sports-related vigorous exercise by
including examples of housework and yard work. Although these
questions provide a more complete picture of the prevalence of
health-related physical activity than those previously used,
other domains, such as transportation and childcare activities,
which are not mentioned in examples, may also
account for activity that is not easily remembered or
reported. Future work in this area should attempt to quantify all
domains so that surveillance systems can monitor and track
patterns of lifestyle physical activity.
The National Health Interview Survey (NHIS) measures moderate-
and vigorous-intensity leisure-time physical activity for
national Healthy People 2010 objectives. However, because
of the sampling frame, it is not feasible to generate
state-specific estimates of physical activity prevalence using
NHIS data. Previous work has shown that state-specific BRFSS data
can be weighted and combined to produce prevalence estimates of
smoking and alcohol use comparable to national surveys (9).
However, the prevalence estimates of physical activity generated
by NHIS and combined BRFSS data will be different because of slight
changes in question wording that have been shown to affect
prevalence (10). In addition, BRFSS can be used by states, some
metropolitan areas, and some counties to monitor progress toward
the Healthy People 2010 objectives for reducing the proportion of adults
who engage in no leisure-time
physical activity as well as increasing the proportion of adults who engage in
regular physical activity of moderate and/or vigorous intensity.
Although the prevalence of U.S. adults achieving recommended
levels of physical activity was higher in 2001 (45.4%) than in
2000 (26.2%) (5), this finding was expected because of the
addition of nonsports-related examples (such as heavy yard work and housework).
Changes in surveillance systems are often
difficult to make and can result in losing the ability to track temporal
trends. The 2001 survey, however, also included a tracking
question that had been used before 2001: “During the past 30 days, other than your regular
job, did you participate in any physical activity or exercise
such as running, calisthenics, golf, gardening, or walking for
exercise?” The prevalence
of inactivity as measured by this question did not
change much from 2000 to 2001 (27.4% to 26.0%), suggesting that
the increases seen in recommended activity (from 26% in 2000 to
45% in 2001) may be primarily because of the expanded definition of
physical activity and the inclusion of the additional examples of yard work and housework (5). Recent data based on
35 states with physical activity data from 1988 to 2002 indicate
that the prevalence of physical inactivity continues to slowly
decrease (25.1% in 2002), which may suggest that recommended
physical activity may increase over time (11).
BRFSS has some limitations. First, it is a telephone-based
system that surveys noninstitutionalized adults residing in the
United States and is thus limited in its ability to capture
people without telephones or those who do not reside at home. Second, all information is self-reported and subject to
potential misclassification bias. Respondents may be prone to
providing socially desirable answers. Third, the statistical issues
involved in combining data from state-specific surveys may have
influenced estimates of the prevalence of physical activity.
It is notable that even with expanded definitions of physical
activity, less than half of the U.S. adult population is achieving
sufficient activity to obtain health benefits. Although the
recommended levels of physical activity as defined here are
associated with health benefits, these are minimal amounts
recommended for adults of all ages; a fully active lifestyle
would include aerobic activities as well as those that increase
strength and flexibility, which were not measured in this study.
Members of the U.S. Preventive Services Task Force have recently
reviewed the literature and identified several effective
interventions that were shown to increase physical activity among
U.S. adults and adolescents (12). Among the recommended
interventions are point-of-decision prompts to encourage stair
use, social support for physical activity in community settings,
individually adapted health behavior change, and creation of
places for physical activity combined with informational outreach
activities. To more fully understand the nature of physical
activity in the population and to assess changes at the
population level that may result from suggested interventions,
future surveillance systems will need to capture purposeful
physical activity (such as stair climbing) that is not usually of
a duration to warrant reporting (at least 10 minutes).
In summary, less than half of U.S. adults meet minimal
physical activity recommendations, even with more inclusive
methods of surveillance that include some lifestyle activities.
Even so, this study identified predictable population differences
that help point the way for population-based promotion
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Corresponding Author: Caroline A. Macera, PhD, Professor of
Epidemiology, Graduate School of Public Health, San Diego State
University, 5500 Campanile Dr, HT 119, San Diego, CA
92182-4162. Telephone: 619-302-2400. E-mail: firstname.lastname@example.org.
Author Affiliations: Sandra A. Ham, MS, Michelle M. Yore,
MSPH, Deborah A. Jones, PhD, C. Dexter Kimsey, PhD, MSEH,
Harold W. Kohl III, PhD, Centers for Disease Control and
Prevention, Division of Nutrition and Physical Activity, Atlanta,
Ga; Barbara E. Ainsworth, PhD, MPH, San Diego State University,
Department of Exercise and Nutritional Sciences, San Diego,
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