James R. Churilla

Sedentary behavior, physical activity, and concentrations of insulin among US adults

Time spent watching television has been linked to obesity, metabolic syndrome, and diabetes, all conditions characterized to some degree by hyperinsulinemia and insulin resistance. However, limited evidence relates screen time (watching television or using a computer) directly to concentrations of insulin. We examined the cross-sectional associations between time spent watching television or using a computer, physical activity, and serum concentrations of insulin using data from 2800 participants aged at least 20 years of the 2003-2006 National Health and Nutrition Examination Survey. The amount of time spent watching television and using a computer as well as physical activity was self-reported. The unadjusted geometric mean concentration of insulin increased from 6.2 microU/mL among participants who did not watch television to 10.0 microU/mL among those who watched television for 5 or more hours per day (P = .001). After adjustment for age, sex, race or ethnicity, educational status, concentration of cotinine, alcohol intake, physical activity, waist circumference, and body mass index using multiple linear regression analysis, the log-transformed concentrations of insulin were significantly and positively associated with time spent watching television (P = < .001). Reported time spent using a computer was significantly associated with log-transformed concentrations of insulin before but not after accounting for waist circumference and body mass index. Leisure-time physical activity but not transportation or household physical activity was significantly and inversely associated with log-transformed concentrations of insulin. Sedentary behavior, particularly the amount of time spent watching television, may be an important modifiable determinant of concentrations of insulin.

The Metabolic Syndrome: How Definition Impacts the Prevalence and Risk in U.S. Adults: 1999–2004 NHANES

BACKGROUND To examine the relationships various medical society definitions have on metabolic syndrome (MetS) prevalence and the likelihood of a MetS diagnosis among a national sample of the United States (US) adult population. METHODS The sample for this study included adults, 20 years and older, (N = 5620) who completed the mobile examination center (MEC) examination in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). SUDAAN statistical software was used to estimate age-adjusted prevalence and odds ratios. RESULTS The overall age-adjusted MetS prevalence ranged from a high of 38.9% (ACE/AACE), to a low of 21.2% (EGIR). For most MetS definitions, males, people in the eighth decade of life (70-79 years of age), Mexican-Americans, those without a high school education, and those living in poverty were found to have the greatest prevalence. Additionally, females were 21% to 33% less likely to be diagnosed with the MetS. People in the seventh decade of life were two to four times more likely to have the MetS compared to those in the third decade of life. Furthermore, adults with greater than a high school education were 26% to 30% less likely to be diagnosed with the MetS and adults in the >/=400% poverty category were 24% to 29% less likely to be diagnosed with the MetS compared to those living below the 100% poverty demarcation. CONCLUSION MetS prevalence and the likelihood of being diagnosed with the MetS within populations are highly dependent on the requisite criteria and medical society definition used.

Relationship between leisure-time physical activity and metabolic syndrome using varying definitions: 1999-2004 NHANES

Purpose: To examine the relationship between leisure-time physical activity (LTPA) and the metabolic syndrome in the U.S. adult population. Methods: The sample (N=5,620) in this cross-sectional study included adults aged 20 years and older. Physical activity was measured in two ways: a six-level measure based upon those reporting no LTPA and quintiles of LTPA, and a three-level categorical measure, according to participants who were found to be inactive, insufficiently active, and those meeting the current public health PA recommendation. SAS and SUDAAN were used for the statistical analysis. Results: When utilising the AHA/NHLBI criteria, adults acquiring between 736 and 1,360 MET·minutes per week (MET·min·wk-1) of LTPA were found to be 35% (OR 0.65; 95% CI 0.48, 0.88) less likely to meet the metabolic syndrome diagnosis criteria compared with those reporting no LTPA. However, protection (OR 0.70; 95% CI 0.51, 0.96) started earlier when utilising the WHO criteria (393—737 MET·min·wk-1). Significant inverse associations (OR 0.54; 95% CI 0.44, 0.66) and (OR 0.61; 95% CI 0.48, 0.77) for WHO and AHA/NHLBI criteria respectively, were also found for the metabolic syndrome when examining LTPA by the current public heath PA recommendation. In addition, the overall age-adjusted prevalence of the metabolic syndrome among U.S. adults was estimated to be 21.9% and 36.3% for the WHO and AHA/ NLHBI definitions respectively. Conclusion: Our findings estimate that adults engaging in a level of LTPA similar to the current public health recommendation may have a decreased risk of developing the metabolic syndrome. Also, depending on the definition used, between one in three and one in five U.S. adults are estimated to have the metabolic syndrome.

Physical Activity: Physical Activity and the Metabolic Syndrome: A Review of the Evidence:

Metabolic syndrome is a global public health problem identified as a seminal cause of cardiovascular disease and type 2 diabetes. The syndrome is characterized by the clustering of cardiovascular risk factors, including insulin resistance, central obesity, hypertension, and atherogenic dyslipidemia. Currently there are 5 working medical society definitions of metabolic syndrome. However, the majority of recent research focusing on metabolic syndrome has relied on the National Cholesterol Education Program (NCEP) definition because of its clinical utility. Studies of the association between physical activity and prevalence of metabolic syndrome using National Health And Nutrition Examination Survey (NHANES) data generally found the association to be reduced or attenuated by other lifestyle factors and is generally weaker in females. Other studies tracking physical activity over longer periods have generally found a stronger association between regular physical activity and lower prevalence or incidence of metabolic syndrome. Interventional studies are limited but suggest that regular exercise reduces the incidence of metabolic syndrome. The amount and intensity of physical activity required to prevent or reverse metabolic syndrome has yet to be definitely determined. Evidence suggests that regular, moderate-intensity physical activity may be preventive of metabolic syndrome and that activity of greater intensity may carry greater benefit. Greater cardiorespiratory fitness has demonstrated an even stronger negative association with metabolic syndrome. Strength training is recommended as an adjunct to regular aerobic exercise but is not the primary form of activity to prevent or manage metabolic syndrome.

Total Activity Counts and Bouted Minutes of Moderate-to-Vigorous Physical Activity: Relationships With Cardiometabolic Biomarkers Using 2003-2006 NHANES.

PURPOSE To contrast associations of accelerometer-measured moderate-to-vigorous physical activity (MVPA) accumulated in bouts and total activity counts (TAC) with cardiometabolic biomarkers in U.S. adults. METHODS Using 2003-2006 National Health and Nutrition Examination Survey (NHANES) data, the sample was comprised of adults ≥ 20 years, not pregnant or lactating, with self-reported PA and at least 4 days of ≥ 10 hours accelerometer wear time (N = 5668). Bouted MVPA represented the minutes/day with ≥ 2020 counts/minute in bouts of 10 minutes or longer and TAC represented the total activity counts per day. Biomarkers included: cholesterol, triglyceride, glycohemoglobin, plasma glucose, C-peptide, insulin, C-reactive protein, homocysteine, blood pressure, body mass index (BMI), waist circumference, and skinfolds. Nested regression models were conducted which regressed each biomarker on bouted MVPA and TAC simultaneously, while adjusting for relevant covariates. RESULTS Results indicated TAC was more strongly associated with 11 biomarkers: HDL-C, triglyceride, plasma glucose, C-peptide, insulin, C-reactive protein, homocysteine, systolic blood pressure, waist circumference, triceps skinfold, and subscapular skinfold. Bouted MVPA, however, only displayed stronger associations with BMI. CONCLUSIONS The total volume of physical activity, represented by TAC, appears to have stronger associations with cardiometabolic biomarkers than MVPA accumulated in bouts.

Comparing physical activity patterns of hypertensive and nonhypertensive US adults.

BACKGROUND Nonpharmacologic management of hypertension is an important strategy in treating people with hypertension, but little is known about patterns of physical activity among such people. We compared patterns of physical activity of adults with and without hypertension in the United States using the most recent guidelines for physical activity. METHODS We used data from 391,017 adults aged > or =18 years from the 2007 Behavioral Risk Factor Surveillance System (BRFSS) and physical activity categories based on 2008 Department of Health and Human Services (DHHS) guidelines. All information was self-reported. RESULTS The age-adjusted prevalence of hypertension was 27.2%, whereas the age-adjusted prevalence of meeting DHHS recommendations was 60.2% among participants with hypertension and 66.9% among participants without hypertension. After adjusting for age, gender, race or ethnicity, education, body mass index (BMI), smoking status, and histories of diabetes and cardiovascular disease (CVD), the odds ratio (OR) for meeting DHHS recommendations among participants with hypertension was 0.85 (95% confidence interval (CI) 0.82, 0.88) compared with those who did not have hypertension. CONCLUSIONS Although the majority of adults with hypertension are currently meeting national guidelines for physical activity, they are less active overall than adults who do not have hypertension.

Muscular strengthening activity patterns and metabolic health risk among US adults

Background:  Many studies have examined the relationship between physical activity and metabolic disorders. However, few have focused on specific associations between these disorders and muscular strengthening activity (MSA) patterns. The aim of the present study was to examine the association(s) for each metabolic syndrome criterion and MSA patterns.

Waist-Worn Actigraphy: Population-Referenced Percentiles for Total Activity Counts in U.S. Adults

BACKGROUND Accelerometer-derived total activity count is a measure of total physical activity (PA) volume. The purpose of this study was to develop age- and gender-specific percentiles for daily total activity counts (TAC), minutes of moderate-to-vigorous physical activity (MVPA), and minutes of light physical activity (LPA) in U.S. adults. METHODS Waist-worn accelerometer data from the 2003-2006 National Health and Nutrition Examination Survey were used for this analysis. The sample included adults ≥ 20 years with ≥ 10 hours accelerometer wear time on ≥ 4 days (N = 6093). MVPA and LPA were defined as the number of 1-minute epochs with counts ≥ 2020 and 100 to 2019, respectively. TAC represented the activity counts acquired daily. TAC, MVPA, and LPA were averaged across valid days to produce a daily mean. RESULTS Males in the 50th percentile accumulated 288 140 TAC/day, with 357 and 22 minutes/day spent in LPA and MVPA, respectively. The median for females was 235 741 TAC/ day, with 349 and 12 minutes/day spent in LPA and MVPA, respectively. CONCLUSIONS Population-referenced TAC percentiles reflect the total volume of PA, expressed relative to other adults. This is a different approach to accelerometer data reduction that complements the current method of looking at time spent in intensity subcategories.

Total physical activity volume, physical activity intensity, and metabolic syndrome: 1999-2004 National Health and Nutrition Examination Survey.

BACKGROUND This study examined the association of total physical activity volume (TPAV) and physical activity (PA) from three domains [leisure-time physical activity (LTPA), domestic, transportation] with metabolic syndrome. We also investigated the relationship between LTPA intensity and metabolic syndrome risk. METHODS Sample included adults who participated in the 1999-2004 National Health and Nutrition Examination Survey. Physical activity measures were created for TPAV, LTPA, domestic PA, and transportational PA. For each, a six-level measure based upon no PA (level 1) and quintiles (levels 2-6) of metabolic equivalents (MET)·min·wk(-1) was created. A three-level variable associated with the current Department of Health and Human Services (DHHS) PA recommendation was also created. SAS and SUDAAN were used for the statistical analysis. RESULTS Adults reporting the greatest volume of TPAV and LTPA were found to be 36% [odds ratio (OR) 0.64; 95% confidence interval (CI) 0.49-0.83] and 42% (OR 0.58; 95% CI 0.43-0.77), respectively, less likely to have metabolic syndrome. Domestic and transportational PA provided no specific level of protection from metabolic syndrome. Those reporting a TPAV that met the DHHS PA recommendation were found to be 33% (OR 0.67; 95%; CI 0.55-0.83) less likely to have metabolic syndrome compared to their sedentary counterparts. Adults reporting engaging in only vigorous-intensity LTPA were found to be 37% (OR 0.63; 95 CI 0.42-0.96) to 56% (OR 0.44; 95% CI 0.29-0.67) less likely to have metabolic syndrome. CONCLUSIONS Volume, intensity, and domain of PA may all play important roles in reducing the prevalence and risk of metabolic syndrome.

Prevalence of Physical Activity Is Lower among Individuals with Chronic Disease.

INTRODUCTION Physical inactivity is associated with increased risk for morbidity and mortality and contributes to health care costs. Although data supporting the secondary preventive benefits of being physically active continues to grow, there is limited data on the prevalence of sufficient volume of leisure-time physical activity among individuals diagnosed with chronic disease. PURPOSE To describe the association between select chronic diseases and the prevalence of sufficient volume of aerobic leisure-time physical activity to achieve substantial health benefits (i.e., ≥150 min·wk) among adults in the United States. METHODS Self-reported leisure-time physical activity (LTPA) and history of select chronic diseases were obtained from a nationally representative sample of noninstitutionalized civilian adults 18 yr or older in the United States who participated in the 2014 National Health Interview Survey (n = 36,697). RESULTS Among all adults, the prevalence of sufficient volume of aerobic LTPA was 50.1% ± 0.5% (mean ± standard error). This prevalence was inversely related to age and was lower in women (47.1% ± 0.6%) compared with men (53.4% ± 0.6%; P < 0.001). Prevalence of sufficient volume of aerobic LTPA was lower for each chronic disease (prevalence range = 26.1%-48.6%) compared with apparently healthy adults (53.6% ± 0.7%). Relative to no chronic disease, each additional chronic disease was associated with an odds ratio of 0.83 (95% confidence interval, 0.81-0.85; P < 0.001) for sufficient volume of aerobic LTPA. CONCLUSIONS The prevalence of sufficient volume of aerobic LTPA to achieve substantial health benefits is inversely related to age and is lower among women and individuals with a chronic disease. Systems to regularly assess physical activity are needed as well as programs to help individuals be more active.