Richard P. Troiano

Amount of Time Spent in Sedentary Behaviors in the United States, 2003–2004

Sedentary behaviors are linked to adverse health outcomes, but the total amount of time spent in these behaviors in the United States has not been objectively quantified. The authors evaluated participants from the 2003-2004 National Health and Nutrition Examination Survey aged >/=6 years who wore an activity monitor for up to 7 days. Among 6,329 participants with at least one 10-hour day of monitor wear, the average monitor-wearing time was 13.9 hours/day (standard deviation, 1.9). Overall, participants spent 54.9% of their monitored time, or 7.7 hours/day, in sedentary behaviors. The most sedentary groups in the United States were older adolescents and adults aged >/=60 years, and they spent about 60% of their waking time in sedentary pursuits. Females were more sedentary than males before age 30 years, but this pattern was reversed after age 60 years. Mexican-American adults were significantly less sedentary than other US adults, and White and Black females were similarly sedentary after age 12 years. These data provide the first objective measure of the amount of time spent in sedentary behavior in the US population and indicate that Americans spend the majority of their time in behaviors that expend very little energy.

Amount of time spent in sedentary behaviors and cause-specific mortality in US adults

BACKGROUND Sedentary behaviors predominate modern life, yet we do not fully understand the adverse effects of these behaviors on mortality after considering the benefits of moderate-vigorous physical activity (MVPA). OBJECTIVE We tested the hypotheses that higher amounts of overall sitting time and television viewing are positively associated with mortality and described the independent and combined effects of these sedentary behaviors and MVPA on mortality. DESIGN In the NIH-AARP Diet and Health Study, we examined 240,819 adults (aged 50-71 y) who did not report any cancer, cardiovascular disease, or respiratory disease at baseline. Mortality was ascertained over 8.5 y. RESULTS Sedentary behaviors were positively associated with mortality after adjustment for age, sex, education, smoking, diet, race, and MVPA. Participants who reported the most television viewing (≥7 h compared with <1 h/d) were at greater risk of all-cause (HR: 1.61; 95% CI: 1.47, 1.76), cardiovascular (HR: 1.85; 95% CI: 1.56, 2.20), and cancer (HR: 1.22; 95% CI: 1.06, 1.40) mortality after adjustment for MVPA. Overall sitting was associated with all-cause mortality. Even among adults reporting high levels of MVPA (>7 h/wk), high amounts of television viewing (≥7 h/d) remained associated with increased risk of all-cause (HR: 1.47; 95% CI: 1.20, 1.79) and cardiovascular (HR: 2.00; 95% CI: 1.33, 3.00) mortality compared with those reporting the least television viewing (<1 h/d). CONCLUSIONS Time spent in sedentary behaviors was positively associated with mortality, and participation in high levels of MVPA did not fully mitigate health risks associated with prolonged time watching television. Adults should be encouraged to reduce time spent in sedentary behaviors, when possible, and to participate in MVPA at recommended levels. The NIH-AARP Diet and Health Study was registered at clinicaltrials.gov as NCT00340015.

Sedentary Activity Associated With Metabolic Syndrome Independent of Physical Activity

OBJECTIVE This study examined the association between objectively measured sedentary activity and metabolic syndrome among older adults. RESEARCH DESIGN AND METHODS Data were from 1,367 men and women, aged ≥60 years who participated in the 2003–2006 National Health and Nutrition Examination Survey (NHANES). Sedentary time during waking hours was measured by an accelerometer (<100 counts per minute). A sedentary bout was defined as a period of time >5 min. A sedentary break was defined as an interruption in sedentary time (≥100 counts per minute). Metabolic syndrome was defined according to the Adult Treatment Panel (ATP) III criteria. RESULTS On average, people spent 9.5 h (65% of wear time) as sedentary. Compared with people without metabolic syndrome, people with metabolic syndrome spent a greater percentage of time as sedentary (67.3 vs. 62.2%), had longer average sedentary bouts (17.7 vs. 16.7 min), had lower intensity during sedentary time (14.8 vs. 15.8 average counts per minute), and had fewer sedentary breaks (82.3 vs. 86.7), adjusted for age and sex (all P < 0.01). A higher percentage of time sedentary and fewer sedentary breaks were associated with a significantly greater likelihood of metabolic syndrome after adjustment for age, sex, ethnicity, education, alcohol consumption, smoking, BMI, diabetes, heart disease, and physical activity. The association between intensity during sedentary time and metabolic syndrome was borderline significant. CONCLUSIONS The proportion of sedentary time was strongly related to metabolic risk, independent of physical activity. Current results suggest older people may benefit from reducing total sedentary time and avoiding prolonged periods of sedentary time by increasing the number of breaks during sedentary time.

Patterns of health behavior in U.S. adults

BACKGROUND Associations between health-related behaviors are important for two reasons. First, disease prevention and health promotion depend on understanding both prevalence of health behaviors and associations among such behaviors. Second, behaviors may have synergistic effects on disease risk. METHODS We document patterns of adherence to recommendations concerning five behaviors (physical activity, tobacco use, alcohol consumption, fruit and vegetable consumption, and dietary fat intake) in U.S. adults (n = 15,425) using data from the Third National Health and Nutrition Examination Survey. Division of individuals into categories associated with adherence or nonadherence to lifestyle recommendations results in 32 patterns of adherence/nonadherence. RESULTS Proportions of U.S. adults with 21 of 32 behavior patterns characterized here deviated from proportions expected if health behaviors are independent of each other. The two extreme patterns, all adherence (5.9%) and all nonadherence (4.9%), were found in about double the proportion expected. Age, gender, race/ethnicity, education, and income were associated with a number of patterns, including the two extremes. CONCLUSIONS This analysis of behavior patterns highlights population subgroups of public health importance, provides a benchmark for studies of multivariate associations between health behaviors, and supports a multidimensional model of health behavior.

Evolution of accelerometer methods for physical activity research

The technology and application of current accelerometer-based devices in physical activity (PA) research allow the capture and storage or transmission of large volumes of raw acceleration signal data. These rich data not only provide opportunities to improve PA characterisation, but also bring logistical and analytic challenges. We discuss how researchers and developers from multiple disciplines are responding to the analytic challenges and how advances in data storage, transmission and big data computing will minimise logistical challenges. These new approaches also bring the need for several paradigm shifts for PA researchers, including a shift from count-based approaches and regression calibrations for PA energy expenditure (PAEE) estimation to activity characterisation and EE estimation based on features extracted from raw acceleration signals. Furthermore, a collaborative approach towards analytic methods is proposed to facilitate PA research, which requires a shift away from multiple independent calibration studies. Finally, we make the case for a distinction between PA represented by accelerometer-based devices and PA assessed by self-report.

The association between urban form and physical activity in U.S. adults

BACKGROUND Physical inactivity is associated with multiple adverse health outcomes. Results from the transportation literature suggest that aspects of the urban environment may influence walking for transportation. In this paper we examine the association between a proxy measure of the urban environment and walking behavior. METHODS We analyzed the association between home age and walking behavior in U.S. adults using data from the Third National Health and Nutrition Examination Survey. Logistic regression was used to estimate odds ratios and 95% confidence intervals and to control for the effects of gender, race/ethnicity, age, education level, household income, and activity limitations. RESULTS Adults who lived in homes built before 1946 and from 1946 to 1973 were significantly more likely to walk 1+ miles > or =20 times per month than those who lived in homes built after 1973. This association was present among people living in urban and suburban counties, but absent among those living in rural counties. The association was also found in models that controlled for gender, race/ethnicity, age, education, income, and any health-related activity limitation. Other forms of leisure-time physical activity were not independently associated with home age. CONCLUSIONS These results support the hypothesis that environmental variables influence walking frequency and suggest that home age may be a useful proxy for features of the urban environment that influence physical activity in the form of walking. Such proxy measures could facilitate testing ecologic models of health behavior using survey data.

Levels and Patterns of Objectively Assessed Physical Activity—A Comparison Between Sweden and the United States

This study compares levels and patterns of objectively assessed physical activity in Sweden and the United States by using identical accelerometer metrics. Data of adult respondents with > or =4 days with > or =10 hours per day of accelerometer wear from Sweden (2001-2002, n = 1,172) and the United States (2003-2004, n = 2,925) were compared. Outcomes reported by age and body mass index within sex include accelerometer counts per minute and amounts and bouts of activity at different intensities, that is, sedentary, low, lifestyle, and moderate or higher intensity physical activity. The mean counts per minute were 375 (95% confidence interval (CI): 360, 390) and 377 (95% CI: 363, 391) for Swedish and US males, respectively, and 363 (95% CI: 347, 379) and 298 (95% CI: 289, 307) for Swedish and US females. Older respondents and those with higher body mass index had lower activity levels. Swedish and US males spent 36 (95% CI: 34, 38) and 33 (95% CI: 31, 36) minutes per day, and Swedish and US females spent 32 (95% CI: 29, 34) and 19 (95% CI: 17, 21) minutes per day in moderate or higher intensity physical activity. Older Swedes were more active in moderate or higher intensity activities than were older US respondents. However, younger Swedish males had more sedentary behavior time than did younger US males. These results provide a framework for international comparisons of physical activity levels and patterns, and they represent strong evidence for the importance of investment in objective measurement of physical activity.

Self-reported and Objectively Measured Activity Related to Biomarkers Using Nhanes

PURPOSE The purpose of this study was to examine the independent associations of self-reported and objectively measured (using accelerometers) moderate to vigorous physical activity (MVPA) with physiological and anthropometric biomarkers in a nationally representative sample of U.S. adults. METHODS Data from the cross-sectional National Health and Nutrition Examination Survey 2003-2006 data were analyzed. Adults 20 yr and older (N=5797) with self-reported PA and 4 d or more of accelerometer data were included in the analyses. Pregnant or lactating women were excluded. Outcomes were blood pressure, body mass index, waist circumference, triceps and subscapular skinfolds, cholesterol, triglyceride, C-reactive protein, homocysteine, and insulin resistance and hyperinsulinemia indices. RESULTS Objectively measured MVPA displayed stronger independent associations with the biomarkers than did self-reported MVPA, even after adjusting for sociodemographic and health factors (adjusted Wald F values=3.9-85.6, P<0.05-0.0001). Self-reported and objectively measured MVPA were independently associated with skinfold measures, HDL, and C-reactive protein when both were included in the model. CONCLUSIONS Objectively measured MVPA displayed stronger associations with physiological and anthropometric biomarkers than self-reported MVPA. However, self-reported and objectively measured MVPA appear to capture distinct aspects of PA that are independently associated with certain biomarkers. Further understanding of the distinct contributions of self-reported and objectively measured PA to health outcomes could help to better identify optimal activity level and pattern.

Physical activity and acculturation among adult hispanics in the United States

Understanding the prevalence and demographic correlates of physical activity is important for public health and epidemiological research. This analysis examines the association between acculturation and physical activity in a large (∼ 5,000) sample of Hispanic adults from the 2000 National Health Interview Survey. Scores for eight questions concerning language use were summed to produce an acculturation index. Factor analysis indicated that these questions assessed a single underlying construct. Self-reported adherence to recommendations concerning leisure time physical activity increased from 22.6% in the least acculturated tertile to 47% in the most acculturated tertile. In contrast, prevalence of walking or bicycling for errands decreased from 25.2 to 18.2%, and prevalence of standing or walking during most of the day decreased from 82.8 to 65.6% as acculturation increased. Thus, patterns of physical activity associated with leisure versus nonleisure time differed among Hispanics with varying acculturation levels. Alternatively, cultural factors may have differential effects on responses to questions concerning leisure and nonleisure time physical activity. In either case, assessing both types of activity is important for monitoring and understanding Hispanic health behaviors and interpreting epidemiological studies that involve physical activity in Hispanics.

Stature and pubertal stage assessment in American boys: the 1988-1994 Third National Health and Nutrition Examination Survey.

PURPOSE To describe current stature and pubertal development in North American boys, and to compare these measures with measures observed approximately 30 years ago. METHODS We analyzed data (i.e., height, weight, and Tanner Stage) from the Third National Health and Nutrition Examination Survey (NHANES III), conducted between 1988-1994, and compared it to the National Health Examination Survey, Cycles II and III (HES II/III), conducted from 1963-1965 and 1966-1970. The surveys included physical examination and questionnaire components, employed cross-sectional designs, and are nationally representative. We used logistic regression to calculate median age at onset of pubertal stages. RESULTS NHANES III included 2481 boys aged 8 to 18 years. HES II comprised 3010 boys aged 8-11 years and HES III comprised 3514 boys aged 12-17 years. The mean heights of the oldest boys in both surveys did not differ significantly; however, at younger ages, boys in the more recent survey were taller (average height difference among those aged 8-14 years was 2.0 cm). Boys in NHANES III were also heavier and had higher body mass index than those in HES II/III. The median estimated ages of onset of pubertal stages in NHANES III were 9.9, 12.2, 13.6, and 15.8 years for genital stages 2-5, respectively, and 11.9, 12.6, 13.6, and 15.7 years for pubic hair stages 2-5, respectively. For some stages, the median estimated age of onset of puberty was earlier among boys in NHANES III than among those in HES III. CONCLUSIONS Differences in mean height at young ages, but not at older ages, suggest that the rate of growth among boys in NHANES III was faster than that of boys in the earlier surveys. This finding, coupled with the finding of earlier ages of onset of some pubertal stages, suggests that boys of this generation may be maturing more rapidly than did boys in the past.