Physical Activity

Physical activity is often classified into different types including recreational or leisure time, utilitarian, household, and occupational. The direct surveillance of physical activity trends in U.S. adults began only in the 1980s and was limited to characterizing leisure-time physical activity. In 2001, CDC began collecting data on the overall frequency and duration of time spent in household, transportation, and leisure-time activity of both moderate and vigorous intensity in a usual week through the state-based Behavioral Risk Factor Surveillance System (BRFSS) (CDC, 2003c).

National surveys conducted over the past several decades suggest an increase in population-wide physical activity levels among American men, women, and older adolescents; however, a large proportion of these populations still do not meet the federal guidelines for recommended levels of total daily physical activity.3 The data for children’s and youth’s leisure time and physical activity levels reveal a different picture than the adult physical activity trend data that are summarized in Table 1-2.

Trend data collected by the Americans’ Use of Time Study, through time-use diaries, indicated that adults’ free time increased by 14 percent between 1965 and 1985 from 35 hours to an average total of nearly 40 hours per week (Robinson and Godbey, 1999). Data from other population-based surveys, including the National Health Interview Survey, National Health and Nutrition Examination Survey (NHANES), BRFSS, and the Family Interaction, Social Capital and Trends in Time Use Data (1998-1999), together with trend data on sports and recreational participation, suggest minor to significant increases in reported leisure-time physical activity among adults (Pratt et al., 1999; French et al., 2001; Sturm, 2004).

Data from the 1990-1998 BRFSS4 revealed only a slight increase in self-reported physical activity levels among adults (from 24.3 percent in 1990 to 25.4 percent in 1998), and a decrease in respondents reporting no physical activity at all (from 30.7 percent in 1990 to 28.7 percent in 1998) (CDC, 2001).

Women, older adults, and ethnic minority populations have been identified as having the greatest prevalence of leisure-time physical inactivity (CDC, 2004b). In general, the prevalence of self-reported, no leisure-time physical activity was highest in 1989, and declined to its lowest level in 15 years among all groups in 35 states and the District of Columbia based on


The Surgeon General’s report on physical activity and health suggests that significant health benefits can be obtained by Americans who include a moderate amount of physical activity (e.g., 30 minutes of brisk walking) on most if not all days of the week (DHHS, 1996).


The BRFSS is a population-based, randomly selected, self-reported telephone survey conducted among the noninstitutionalized U.S. adult population aged 18 years and older throughout the 50 states (CDC, 2003c).

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