Susan A. Carlson

Trend and Prevalence Estimates Based on the 2008 Physical Activity Guidelines for Americans

BACKGROUND According to the 2008 Physical Activity Guidelines for Americans, adults need to engage in at least 150 minutes/week of moderate-intensity activity or its equivalent (defined as aerobically active) to obtain substantial health benefits and more than 300 minutes/week (defined as highly active) to obtain more extensive health benefits. In addition to aerobic activity, the 2008 Guidelines recommend that adults participate in muscle-strengthening activities on 2 or more days/week. PURPOSE This study examined the prevalence and trends of meeting the activity criteria defined by the 2008 Guidelines among U.S. adults. METHODS Prevalence and trends of participation in leisure-time physical activity were estimated from the 1998-2008 National Health Interview Survey (analyzed in 2010). RESULTS In 2008, 43.5% of U.S. adults were aerobically active, 28.4% were highly active, 21.9% met the muscle-strengthening guideline, and 18.2% both met the muscle-strengthening guideline and were aerobically active. The likelihood of meeting each of these four activity criteria was similar and were associated with being male, being younger, being non-Hispanic white, having higher levels of education, and having a lower BMI. Trends over time were also similar for each part of the 2008 Guidelines, with the prevalence of participation exhibiting a small but significant increase when comparing 1998 to 2008 (difference ranging from 2.4 to 4.2 percentage points). CONCLUSIONS Little progress has been made during the past 10 years in increasing physical activity levels in the U.S. There is much room for improvement in achieving recommended levels of physical activity among Americans, particularly among relatively inactive subgroups.

Physical Education and Academic Achievement in Elementary School: Data From the Early Childhood Longitudinal Study

OBJECTIVES We examined the association between time spent in physical education and academic achievement in a longitudinal study of students in kindergarten through fifth grade. METHODS We used data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998 to 1999, which employed a multistage probability design to select a nationally representative sample of students in kindergarten (analytic sample = 5316). Time spent in physical education (minutes per week) was collected from classroom teachers, and academic achievement (mathematics and reading) was scored on an item response theory scale. RESULTS A small but significant benefit for academic achievement in mathematics and reading was observed for girls enrolled in higher amounts (70-300 minutes per week) of physical education (referent: 0-35 minutes per week). Higher amounts of physical education were not positively or negatively associated with academic achievement among boys. CONCLUSIONS Among girls, higher amounts of physical education may be associated with an academic benefit. Physical education did not appear to negatively affect academic achievement in elementary school students. Concerns about adverse effects on achievement may not be legitimate reasons to limit physical education programs.

Influence of limit-setting and participation in physical activity on youth screen time.

OBJECTIVES: To examine the associations of demographics, rules associated with television-viewing, and physical activity with daily screen time (including television, non–school-related computer use, and video games) in children and adolescents. METHODS: We analyzed data from a telephone survey of 7415 youth aged 9 to 15 years from the Youth Media Campaign Longitudinal Survey. We used logistic regression models to calculate odds of exceeding recommended screen-time limits (>120 minutes/day) according to demographics, rules, and physical activity. RESULTS: Odds that children would exceed recommended screen-time limits were positively associated with age and black race/ethnicity and negatively associated with income level. Children and adolescents who reported that they really agreed that their parents had rules about time spent watching television and playing video games were less likely to exceed recommended limits than those who strongly disagreed that their parents had rules. Similarly, when parents reported always or very often having limits on television watching (versus rarely or never) and when parents correctly identified the recommended limits, children were less likely to exceed recommended limits. Children whose parents reported consistent limits and who themselves reported consistent rules about time spent watching television had the lowest prevalence of exceeding recommended limits. Odds that children would exceed recommended limits decreased as physical activity in the previous week increased. CONCLUSIONS: Parental rules regarding screen time and participation in physical activity play a role in the amount of screen time among children and adolescents. Programs that encourage limit-setting by parents and promote physical activity may reduce screen time among youth.

Leisure-time aerobic physical activity, muscle-strengthening activity and mortality risks among US adults: the NHANES linked mortality study.

Background Regular physical activity elicits multiple health benefits in the prevention and management of chronic diseases. We examined the mortality risks associated with levels of leisure-time aerobic physical activity and muscle-strengthening activity based on the 2008 Physical Activity Guidelines for Americans among US adults. Methods We analysed data from the 1999 to 2004 National Health and Nutrition Examination Survey with linked mortality data obtained through 2006. Cox proportional HRs with 95% CIs were estimated to assess risks for all-causes and cardiovascular disease (CVD) mortality associated with aerobic physical activity and muscle-strengthening activity. Results Of 10 535 participants, 665 died (233 deaths from CVD) during an average of 4.8-year follow-up. Compared with participants who were physically inactive, the adjusted HR for all-cause mortality was 0.64 (95% CI 0.52 to 0.79) among those who were physically active (engaging in ≥150 min/week of the equivalent moderate-intensity physical activity) and 0.72 (95% CI 0.54 to 0.97) among those who were insufficiently active (engaging in >0 to <150 min/week of the equivalent moderate-intensity physical activity). The adjusted HR for CVD mortality was 0.57 (95% CI 0.34 to 0.97) among participants who were insufficiently active and 0.69 (95% CI 0.43 to 1.12) among those who were physically active. Among adults who were insufficiently active, the adjusted HR for all-cause mortality was 44% lower by engaging in muscle-strengthening activity ≥2 times/week. Conclusions Engaging in aerobic physical activity ranging from insufficient activity to meeting the 2008 Guidelines reduces the risk of premature mortality among US adults. Engaging in muscle-strengthening activity ≥2 times/week may provide additional benefits among insufficiently active adults.

Trends in No Leisure-Time Physical Activity--United States, 1988-2010.

Purpose: The aim of this study was to examine trends in the prevalence of no leisure-time physical activity (LTPA) from 1988 to 2010. Method: Using the Behavioral Risk Factor Surveillance System data, 35 states and the District of Columbia reported information on no LTPA from 1988 to 1994; all states reported no LTPA from 1996 to 2010. Results: No LTPA significantly declined over two decades. Prevalence for all states declined on an average of 0.6% per year from 29.1% in 1996 to 24.1% in 2004 and stabilized from 2005 to 2010, ranging from 24.0% to 25.4%. Prevalence declined for both sexes and all racial/ethnic groups. Conclusion: While the no LTPA trends improved over two decades, one in four U.S. adults still report they do not engage in LTPA.

Awareness and knowledge of the 2008 Physical Activity Guidelines for Americans.

BACKGROUND To estimate the proportion of U.S. adults aware and knowledgeable of the 2008 Physical Activity Guidelines for Americans. METHODS Analysis is based on a cross-sectional national sample of adults in the 2009 (n = 4281) HealthStyles survey. We estimated the prevalence of adults who reported awareness of government physical activity guidelines and who were knowledgeable of the currently recommended moderate-intensity physical activity guideline (ie, 150 minutes per week) from the 2008 Guidelines. RESULTS In 2009, the percent of adults who reported being aware of government physical activity (PA) guidelines was 36.1%. The percent of adults knowledgeable of the moderate-intensity physical activity guideline was less than 1% (0.56%). CONCLUSIONS Most U.S. adults lack sufficient awareness and knowledge of the 2008 Guidelines, putting them at risk for failure to meet them. The nation needs more effective communication strategies to translate and disseminate PA guidelines.

Muscle-Strengthening Activities and Participation Among Adults in the United States

Purpose: To describe those who reported meeting the 2008 Physical Activity Guidelines for Americans (2008 Guidelines) muscle-strengthening standard of 2 or more days per week, including all seven muscle groups, and to assess the type and location of muscle-strengthening activities performed. Method: Data from HealthStyles 2009, a cross-sectional, consumer mail-panel survey, was used for analyses (n = 4,271). The prevalence estimates with 95% confidence intervals of those meeting the 2008 Guidelines standards were calculated. Pairwise t-tests were performed to examine differences between estimates, tests for linear trends were performed among age, education, and body mass index (BMI) groups, and differences and trends were considered statistically significant at p < .05. Results: Overall, 6.0% of participants reported meeting 2008 Guidelines, and there were no significant differences between sex and racial/ethnic groups. A significant linear increase was noted among education groups, with respondents who reported lower levels of educational attainment having lower levels of participation compared with respondents who reported higher levels of educational attainment. A significant linear decrease was noted among each BMI group, with those classified as underweight/normal reporting higher levels of participation, compared with those classified as obese. Free weights and calisthenics were the most common types of activities; the home was the most common location. Conclusions: Few adults reported meeting current muscle-strengthening standards. Future public health efforts to increase participation should use the most frequently reported type and location of muscle-strengthening activities outlined in this study to guide interventions and communication campaigns.

Prevalence of highly active adults—Behavioral risk factor surveillance system, 2007

BACKGROUND The 2008 Physical Activity Guidelines for Americans (2008 Guidelines) included a novel aerobic physical activity standard, in excess of minimum standards, for more extensive health benefits (>300 minutes/week of moderate-intensity, 150 minutes/week of vigorous-intensity, or an equivalent combination). Prevalence estimates among US states have yet to be described for this new standard. METHODS Respondents self-reported physical activity in the 2007 Behavioral Risk Factor Surveillance System was used (n=398,397). Total weekly aerobic activity was calculated for each respondent and 2008 Guidelines standards guided classification. RESULTS In 2007, 43.5% (95% CI: 43.1%-43.8%) of adults met the new 2008 Guidelines standard and were classified as highly active (male, 48.3%; female, 38.9%). Linear patterns were noted by age and education, where younger age and higher levels of education had a higher proportion of highly active. Non-Hispanic whites (45.7%) had a significantly higher proportion of highly active compared with non-Hispanic blacks (37.5%) and Hispanics (37.6%). Variations in estimates were noted among those categorized as sufficiently active, insufficiently active, and inactive. CONCLUSION More than half of 2007 Behavioral Risk Factor Surveillance System respondents did not meet the new 2008 Guidelines standard. Aerobic activity levels commensurate with more extensive health benefits should be encouraged among US adults.

Household Transmission of 2009 Pandemic Influenza A (H1N1) and Nonpharmaceutical Interventions among Households of High School Students in San Antonio, Texas

San Antonio, Texas, was one of the first metropolitan areas where 2009 pandemic influenza A (H1N1) virus (pH1N1) was detected. Identification of laboratory-confirmed pH1N1 in 2 students led to a preemptive 8-day closure of their high school. We assessed transmission of pH1N1 and changes in adoption of nonpharmaceutical interventions (NPIs) within households of students attending the affected school. Household secondary attack rates were 3.7% overall and 9.1% among those 0-4 years of age. Widespread adoption of NPIs was reported among household members. Respondents who viewed pH1N1 as very serious were more likely to adopt certain NPIs than were respondents who viewed pH1N1 as not very serious. NPIs may complement influenza vaccine prevention programs or be the only line of defense when pandemic vaccine is unavailable. The 2009 pandemic provided a unique opportunity to study NPIs, and these real-world experiences provide much-needed data to inform pandemic response policy.

Walking for Transportation and Leisure among U.S. Adults—National Health Interview Survey 2010

BACKGROUND Walking, the most commonly reported physical activity among U.S. adults, is undertaken in various domains, including transportation and leisure. METHODS This study examined prevalence, bout length, and mean amount of walking in the last week for transportation and leisure, by selected characteristics. Self-reported data from the 2010 National Health Interview Survey (N = 24,017) were analyzed. RESULTS Prevalence of transportation walking was 29.4% (95% CI: 28.6%-30.3%) and of leisure walking was 50.0% (95% CI: 49.1%-51.0%). Prevalence of transportation walking was higher among men; prevalence of leisure walking was higher among women. Most (52.4%) transportation walking bouts were 10 to 15 minutes; leisure walking bouts were distributed more evenly (28.0%, 10-15 minutes; 17.1%, 41-60 minutes). Mean time spent in transportation walking was higher among men, decreased with increasing BMI, and varied by race/ethnicity and region of residence. Mean time spent leisure walking increased with increasing age and with decreasing BMI. CONCLUSION Demographic correlates and patterns of walking differ by domain. Interventions focusing on either leisure or transportation walking should consider correlates for the specific walking domain. Assessing prevalence, bout length, and mean time of walking for transportation and leisure separately allows for more comprehensive surveillance of walking.