Time of eating and mortality in U.S. adults with heart failure: Analyses of the National Health and Nutrition Examination Survey 2003-2018.

BACKGROUND AND AIMS: Promising associations have been demonstrated between delayed last eating occasion and cardiorespiratory fitness in adults with heart failure (HF), however, it is unknown if time of eating is associated with clinical endpoints such as mortality. This study aimed to examine associations between time of eating variables and all-cause and cardiovascular mortality in the National Health and Nutrition Examination Survey (NHANES). METHODS AND RESULTS: Participants self-disclosed HF diagnosis. Two dietary recalls were obtained and categorical variables were created based on mean time of first eating occasion (8:31 AM), last eating occasion (7:33 PM) and eating window (11.02 h). Mortality was obtained through linkage to the National Death Index. Covariate-adjusted Cox proportional hazard regression models were created examining the association between time of eating and mortality. Participants (n = 991) were 68 (95 % CI 67-69) years of age, 52.6 (95 % CI 49.0-56.3)% men and had a body mass index of 32.5 (95 % CI 31.8-33.2) kg/m2 with follow up time of 68.9 (95 % CI 64.8-72.9) person-months. When models were adjusted for time of eating variables and all other covariates, extending the eating window beyond 11.02 h was associated with decreased risk of cardiovascular (HR 0.36 [95 % CI 0.16-0.81]), but not all-cause mortality. Time of first and last eating occasions were not associated with mortality. CONCLUSIONS: In adults with HF, an extended eating window is associated with reduced risk for cardiovascular mortality. Randomized controlled trials should examine if extending the eating window can improve prognostic indicators such as cardiorespiratory fitness in this population.

COPD is associated with increased cardiovascular disease risk independent of phenotype.

BACKGROUND AND OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide that frequently presents with concomitant cardiovascular diseases. Despite the pathological distinction between individual COPD phenotypes such as emphysema and chronic bronchitis, there is a lack of knowledge about the impact of COPD phenotype on cardiovascular disease risk. Thus, this study aimed to utilize a nationally representative sample to investigate cardiovascular disease prevalence in patients with COPD with emphysema and chronic bronchitis phenotypes. METHODS: Data from 31,560 adults including 2504 individuals with COPD, collected as part of the National Health and Nutrition Examination Survey (1999-2018), were examined. RESULTS: A significantly increased cardiovascular disease risk, including coronary heart disease, heart failure, myocardial infarction and stroke, was identified in patients with COPD among all disease phenotypes. Particularly, compared to those without COPD, individuals with chronic bronchitis presented with 1.76 (95% CI: 1.41-2.20) times greater odds, individuals with emphysema with 2.31 (95% CI: 1.80-2.96) times greater odds, while those with a concurrent phenotype (combined chronic bronchitis and emphysema) exhibited 2.98 (95% CI: 2.11-4.21) times greater odds of reporting cardiovascular diseases. CONCLUSION: Our data confirms that patients with COPD present an elevated risk of developing cardiovascular disease among all phenotypes, with the most marked increase being in those with concurrent chronic bronchitis and emphysema phenotypes. These findings emphasize the need for awareness and appropriate cardiovascular screening in COPD.

Effects of a mitochondrial-targeted ubiquinol on vascular function and exercise capacity in chronic kidney disease: a randomized controlled pilot study.

Mitochondria-derived oxidative stress has been implicated in vascular and skeletal muscle abnormalities in chronic kidney disease (CKD). The purpose of this study was to investigate the effects of a mitochondria-targeted ubiquinol (MitoQ) on vascular function and exercise capacity in CKD. In this randomized controlled trial, 18 patients with CKD (means ± SE, age: 62 ± 3 yr and estimated glomerular filtration rate: 45 ± 3 mL/min/1.73 m2) received 4 wk of 20 mg/day MitoQ (MTQ group) or placebo (PLB). Outcomes assessed at baseline and follow-up included macrovascular function measured by flow-mediated dilation, microvascular function assessed by laser-Doppler flowmetry combined with intradermal microdialysis, aortic hemodynamics assessed by oscillometry, and exercise capacity assessed by cardiopulmonary exercise testing. Compared with PLB, MitoQ improved flow-mediated dilation (baseline vs. follow-up: MTQ, 2.4 ± 0.3% vs. 4.0 ± 0.9%, and PLB, 4.2 ± 1.0% vs. 2.5 ± 1.0%, P = 0.04). MitoQ improved microvascular function (change in cutaneous vascular conductance: MTQ 4.50 ± 2.57% vs. PLB -2.22 ± 2.67%, P = 0.053). Central aortic systolic and pulse pressures were unchanged; however, MitoQ prevented increases in augmentation pressures that were observed in the PLB group (P = 0.026). MitoQ did not affect exercise capacity. In conclusion, this study demonstrates the potential for a MitoQ to improve vascular function in CKD. The findings hold promise for future investigations of mitochondria-targeted therapies in CKD.NEW & NOTEWORTHY In this randomized controlled pilot study, we investigated the effects of a mitochondria-targeted ubiquinol (MitoQ) on vascular function and exercise capacity in chronic kidney disease. Our novel findings showed that 4-wk supplementation of MitoQ was well tolerated and improved macrovascular endothelial function, arterial hemodynamics, and microvascular function in patients with stage 3-4 chronic kidney disease. Our mechanistic findings also suggest that MitoQ improved microvascular function in part by reducing the NADPH oxidase contribution to vascular dysfunction.

The association of fitness and fatness with intermediate hyperglycemia incidence in women: A cohort study.

The purpose of this study was to examine the associations of cardiorespiratory fitness, general adiposity, and central adiposity with incident intermediate hyperglycemia (IH) in women. We conducted a prospective cohort study of 1534 women aged 20-79 years old who had an annual health check-up with no history of major chronic diseases. At baseline, fitness was assessed by a Balke graded exercise test, and the estimated metabolic equivalents were used to create quartile groups. Women were also grouped based on their body mass index (<25 kg/m2, 25-29.9 kg/m2, and ≥ 30 kg/m2) and waist-to-height ratio (≥0.50 or < 0.50). Cox proportional hazards models were conducted to assess the association of fitness and fatness variables with incident IH defined as fasting glucose of 5.6-6.9 mmol/L. Overall, 18.1% (n = 277) of the women developed IH during an average follow-up of 5.06 years. Fitness, body mass index, and waist-to-height ratio at baseline were the independent predictors of the IH incidence in separate age-adjusted models; yet when all three variables were included in the same model along with confounding variables, only fitness remained significant and demonstrated a clear inverse association with incident IH (P-for-trend <0.001). Health promotion efforts should focus on improving fitness for the prevention of IH in women.

Personal social capital and self-rated health among middle-aged and older adults: a cross-sectional study exploring the roles of leisure-time physical activity and socioeconomic status.

BACKGROUND: Personal social capital, which refers to the scope and quality of an individual's social networks within a community, has received increasing attention as a potential sociological factor associated with better individual health; yet, the mechanism relating social capital to health is still not fully understood. This study examined the associations between social capital and self-rated health while exploring the roles of leisure-time physical activity (LTPA) and socioeconomic status (SES) among middle-aged and older adults. METHODS: Cross-sectional data were collected from 662 middle-aged and older adults (Mean age: 58.11 ± 10.59 years old) using the Qualtrics survey panel. Personal Social Capital Scale was used to measure bonding and bridging social capital and the International Physical Activity Questionnaire was used to assess LTPA levels. SES was assessed by education and household income levels. Self-rated health was assessed using a single item, by which the participants were categorized into the two groups, having 'good' vs. 'not good' self-rated health. A series of univariate and multivariate logistic regression models were established to examine the independent and adjusted associations of social capital with self-rated health and to test mediating and moderating roles of LTPA and SES, respectively. RESULTS: Bonding and bridging social capital were positively associated with self-rated health (Odds ratios = 1.11 and 1.09; P's < .05, respectively), independent of LTPA that was also significantly associated with greater self-rated health (P-for-linear trends = .007). After adjusting SES, the associations of social capital were significantly attenuated and there was a significant interaction effect by household income (P-for-interaction = .012). Follow-up analyses stratified by household income showed that beneficial associations of social capital with self-rated health were more apparent among the people with low and high levels of household income; yet, LTPA was the stronger predictor of self-rated health among those in the middle class of household income. CONCLUSIONS: Findings suggest that both social capital and LTPA are associated with better self-rated health; yet, these associations vary by SES. The health policymakers should address both social capital and LTPA for enhancing perceived health among aging populations but may need to consider varying SES backgrounds.

Life satisfaction in persons with spinal cord injury across the seasons.

STUDY DESIGN: Longitudinal study. OBJECTIVES: This study aimed to examine level and variations of life satisfaction (LS) across the seasons in persons with spinal cord injury (SCI). SETTING: Polish sample of persons with SCI. METHODS: The study included 56 persons with SCI, who repeatedly completed the Life Satisfaction Questionnaire (LiSaT-9), and a study-specific questionnaire across the four seasons in a calendar year. Mixed model analyses were performed to: (1) examine seasonal changes in LS; (2) explore the possible moderating factors on seasonal changes in LS. RESULTS: There were significant seasonal trends in overall and domain-specific LS scores; yet, these changes differed in terms of shape (i.e. linear vs. quadratic). In general, the highest LS scores occurred in spring across all domains, followed by a significant reduction in summer; yet, there were u-shape trends in LS domain scores for life as a whole, vocational, and financial situation and partner relations (P-for-quadratic trends ≤0.05). Five individual characteristics, i.e. place of living, education, gender, physical activity, and time since injury significantly moderated seasonal trends in LS scores (P's for interaction ≤ 0.05). CONCLUSION: Life satisfaction in persons with SCI differs significantly in relation to different seasons throughout a year. The season of the year should be considered in future studies on LS and included in evaluating and projecting healthcare interventions or programs for persons with SCI.

Development of an inside-out augmented reality technique for neurosurgical navigation.

OBJECTIVE: With the advancement of 3D modeling techniques and visualization devices, augmented reality (AR)-based navigation (AR navigation) is being developed actively. The authors developed a pilot model of their newly developed inside-out tracking AR navigation system. METHODS: The inside-out AR navigation technique was developed based on the visual inertial odometry (VIO) algorithm. The Quick Response (QR) marker was created and used for the image feature-detection algorithm. Inside-out AR navigation works through the steps of visualization device recognition, marker recognition, AR implementation, and registration within the running environment. A virtual 3D patient model for AR rendering and a 3D-printed patient model for validating registration accuracy were created. Inside-out tracking was used for the registration. The registration accuracy was validated by using intuitive, visualization, and quantitative methods for identifying coordinates by matching errors. Fine-tuning and opacity-adjustment functions were developed. RESULTS: ARKit-based inside-out AR navigation was developed. The fiducial marker of the AR model and those of the 3D-printed patient model were correctly overlapped at all locations without errors. The tumor and anatomical structures of AR navigation and the tumors and structures placed in the intracranial space of the 3D-printed patient model precisely overlapped. The registration accuracy was quantified using coordinates, and the average moving errors of the x-axis and y-axis were 0.52 ± 0.35 and 0.05 ± 0.16 mm, respectively. The gradients from the x-axis and y-axis were 0.35° and 1.02°, respectively. Application of the fine-tuning and opacity-adjustment functions was proven by the videos. CONCLUSIONS: The authors developed a novel inside-out tracking-based AR navigation system and validated its registration accuracy. This technical system could be applied in the novel navigation system for patient-specific neurosurgery.

Compensatory adjustments in motor unit behavior during fatigue differ for younger versus older men.

BACKGROUND: The ability to maintain a submaximal force as a muscle fatigues is supplemented by compensatory adjustments in the nervous system's control of motor units. AIM: We sought to compare vastus lateralis motor unit recruitment and firing rate data for younger versus older men during isometric fatigue. METHODS: Twelve younger (age = 25 ± 3 years) and 12 older (75 ± 8 years) men performed contractions of the knee extensors at 50% of maximal voluntary contraction force until exhaustion. Surface electromyographic (sEMG) signals were detected from the vastus lateralis. A sEMG signal decomposition algorithm was used to quantify the motor unit action potential (MUAP) amplitude, mean firing rates, and recruitment threshold of each motor unit. For the latter two variables, our analyses only included motor units that featured similar action potential amplitude throughout the protocol. RESULTS: There was no group difference for time to task failure (p = 0.362, d = 0.381). Both groups showed increases in MUAP amplitude [younger and older slopes = 0.0174 ± 0.0123 and 0.0073 ± 0.0123 mV/contraction, respectively (p = 0.082, d = 0.710)], but the change was more linear for the younger men (mean r2 values = 0.565 and 0.455). Mean firing rates increased over time for the younger (p < 0.001), but not the older (p = 0.579), men. Similarly, recruitment thresholds decreased for younger men (p = 0.001). CONCLUSION: We propose that aging results in neuromuscular impairments that hinder older adults' ability to make compensatory adjustments in motor unit control during fatigue.

An Investigation of Short-Term Longitudinal Associations Between Handgrip Strength and Cardiovascular Disease Biomarkers Among Middle-Aged to Older Adults: A Project FRONTIER Study.

The purpose of this study was to examine short-term longitudinal relationships between handgrip strength (HGS) and cardiovascular disease (CVD) biomarkers in middle-aged to older adults living in rural areas (N = 138). The association between HGS and CVD biomarkers was examined at baseline, with HGS as a predictor of the annual change in biomarkers, and in a parallel fashion between the annual change in HGS and CVD biomarkers over an average of 2.8 follow-up years. The results showed HGS to cross-sectionally associate with waist circumference and diastolic blood pressure at baseline, but HGS at baseline was not found to predict the annual change in any biomarker. The annual increase in HGS was significantly associated with favorable changes in high-density lipoprotein cholesterol, triglycerides, and systolic/diastolic blood pressures; yet, these associations varied by the baseline levels of biomarkers. The present findings suggest that improved muscle strength with aging is related to favorable changes in CVD biomarkers.

The effects of a teaching intervention on weight bias among kinesiology undergraduate students.

OBJECTIVES: Weight bias is present among kinesiology professionals and this may cause a significant negative impact on their clients with obesity. Thus, our objective was to test if learning about uncontrollable cause of obesity and about weight bias would reduce explicit and implicit weight bias among kinesiology undergraduate students compared to the traditional curriculum which is more focused on controllable causes of weight gain. METHODS: We recruited undergraduates from two classes of the same kinesiology major course taught by the same instructor. In-class teaching activities consisted of 80 min lecture on day 1, video watching session and a group activity on day 3 for both groups. Intervention group (n = 33) learned about uncontrollable causes of obesity and about weight bias and had activities to evoke empathy. Control group (n = 34) learned the traditional curriculum where they learned the role of exercise and diet in weight management. We measured explicit and implicit weight bias using Anti-Fat Attitude Test (AFAT) and Implicit Association Test (IAT), respectively pre-intervention, immediate post intervention and 1 month later. RESULTS: In mixed model analysis, AFAT Blame scores had significant group by time interaction (p < 0.001). Blame scores significantly reduced with mean differences (standard error (SE)) of -0.35 (0.08) post intervention (p < 0.001) and persisted to be reduced with mean differences (SE) of -0.39 (0.08) even after 4-week follow-up (p < 0.001) only in the intervention group. Odds of having less implicit weight bias was significantly lower at 4-week follow-up than pre-intervention (odds ratio = 0.4; 95% CI: 0.22-0.73) in the control group but no changes were seen in the intervention group. CONCLUSIONS: "Blame" component of explicit weight bias significantly decreased when students learned about controllable causes of obesity and weight bias, but implicit bias did not reduce. However, implicit weight bias appears to increase when education on obesity is limited to diet and exercise interventions as taught in the traditional curriculum.

Wellness programme at the workplace promotes dietary change and improves health indicators in a longitudinal retrospective study.

OBJECTIVE: To determine the effectiveness of a workplace wellness programme intervention in improving participants' behaviour towards choosing a healthy diet and the correlation with health indicators. DESIGN: A retrospective cohort study. SETTING: Wellness programme in the Midwest, USA. SUBJECTS: Employees (n 12 636) who participated in a wellness programme for three consecutive years during years 2004 to 2013 and who completed web-based health risk questionnaires. The wellness programme included annual health screening, laboratory measures, health risk questionnaire and personalized health-care programme. Participants' food group intakes, BMI and health indicators were compared between the first and last year of participation. McNemar's non-parametric test was used for paired nominal data. Pearson correlations were computed for paired food and health indicator measurements. Correlations between dietary intake and BMI, cholesterol and TAG were computed using Pearson correlations and McNemar's test. RESULTS: There were negative correlations between intakes of fruits, vegetables, grains, dairy, healthy eating pattern and health outcome indicators such as BMI and TAG levels. Additionally, the percentage of employees who increased their consumption of fruits (16·88 v. 12·08 %, P<0·001), vegetables (15·20 v. 11·44 %, P<0·001) and dark green leafy vegetables (12·03 v. 7·27 %, P 0·001) was significantly higher than the percentage of participants who decreased their intake of these food groups during the third-year follow-up. CONCLUSIONS: The wellness programme improved some health indicator parameters and had a positive impact on increasing participants' intakes of fruits, vegetables and whole grains at the third year of follow-up.

Association between objectively measured sedentary behavior and a criterion measure of obesity among adults.

OBJECTIVE: Results of published studies on the association between sedentary behavior (SB) and obesity are inconsistent, possibly due to reliance on subjective measures of SB and inappropriate measures of obesity. The aim of this study was to examine the relationship between objectively measured SB and criterion-measured obesity among adults. METHODS: A total of 2284 adults (≥18 years) from the 2003 to 2004 National Health and Nutrition Examination Survey were included in the analysis. The participants were categorized into tertiles of SB time measured by accelerometry. Obesity was determined using body fat percentage measured by dual-energy X-ray absorptiometry. RESULTS: Increased SB was significantly associated with obesity when controlling for covariates related to demographics, health behaviors, energy intake, and physical activity (P for trends = .025). CONCLUSIONS: This finding suggests that avoiding SB may be beneficial for lowering the risk of obesity in adults.

Promoting physical activity using a wearable activity tracker in college students: A cluster randomized controlled trial.

This study examined the effects of utilizing a wearable activity tracker in a credit-based physical activity instructional program (PAIP) for promoting physical activity (PA) in college students. Fourteen PAIP courses in a large public university were randomly assigned into intervention (k = 7; n = 101) and control (k = 7; n = 86) groups. All courses focused on a core curriculum that covers basic exercise and behavioral science contents through lectures and activity sessions. A Misfit Flash activity tracker was provided to students in the intervention group. Objective PA assessments occurred at baseline, mid-, and end-of-semester during a 15-week academic semester. The control group showed a significant reduction in moderate- and vigorous-intensity PA (MVPA) minutes from baseline to the end-of-semester (P <.05), whereas the intervention group showed no changes in MVPA minutes over time. However, the intervention group also showed increased sedentary time and decreased time spent in light-intensity PA during the intervention period. Taken together, the present study found null effects of utilizing the wearable activity tracker in promoting PA in college students suggesting that intervention of primary using the wearable activity tracker as a behavior change strategy may not be effective to increase in PA in this setting.

Trajectory analysis of discrete goal-directed pointing movements: How many trials are needed for reliable data?

A powerful tool in motor behavior research is trajectory analysis of discrete goal-directed pointing movements. The purpose of the present analysis was to estimate the minimum number of trials per participant required to achieve the conventional level of reliability for trajectory analysis. We analyzed basic measurements of movement and three common methods of trajectory analysis within the framework of generalizability theory. Generalizability studies were used to decompose the total variance of these variables into the percent contributions from person, trial, and the person-by-trial interaction. Decision studies were then used to determine the minimum number of trials required to achieve the conventional level of reliability. The number of trials per participant needed for reliable data of discrete goal-directed pointing movements depended on the dependent variable-for example, reaction times required six or ten trials, movement times required three trials, and constant error required 47 trials. For trajectory analysis, ten or fewer trials were required for reliable dependent variables during the first half of the movement (up to peak velocity or 70% of the displacement). The number of trials required for the second half of the movement rapidly increased to 47 trials at movement termination. This increase in the number of trials required for reliable analysis of the second half of the movement was indicative of online control. Finally, correlation analysis was performed with simulated correlations on subsets of trials, and all 32 trials were required. However, 18 trials might be used without a practically significant change in the correlations.

Does l-citrulline supplementation improve exercise blood flow in older adults?

NEW FINDINGS: What is the central question of this study? Does short-term supplementation with l-citrulline in order to increase l-arginine improve exercise blood flow and peripheral dilatation responses to exercise in older adults? What is the main finding and its importance? l-Citrulline increased femoral blood flow by 11% and vascular conductance by 14% during lower-limb exercise in older men, whereas no changes were observed in older women. This modest improvement in bulk muscle blood flow in older men has implications for altering muscle metabolism that may result in enhanced exercise tolerance in older adults. l-Citrulline (Cit) increases l-arginine (Arg), the primary substrate for nitric oxide biosynthesis. We tested the hypothesis that muscle blood flow during exercise would be enhanced by Cit supplementation in older adults. Femoral artery blood flow was measured during calf exercise using Doppler ultrasound, and vascular conductance (FVC) was calculated in 25 older adults (13 women and 12 men) before and after 14 days of Cit (6 g day-1 ) and placebo (maltodextrin) in a randomized, double-blind, crossover study. Plasma [Arg] and resting blood pressure were also measured before and after each condition. Women and men were analysed separately because of significant sex-by-condition interactions for the change in exercise blood flow and FVC. Plasma [Arg] was increased by 30 and 35% after Cit (P < 0.01) in women and men, respectively, with no change after placebo. Citrulline lowered diastolic blood pressure in men (75 ± 9 versus 71 ± 6 mmHg, P = 0.02), but this variable remained unchanged in women. Blood flow and FVC during exercise at higher workloads were increased after Cit in men (flow, 521 ± 134 versus 584 ± 166 ml min-1 , P = 0.04; FVC, 5.0 ± 1.5 versus 5.8 ± 1.7 m, min mmHg-1 , P = 0.01) but were not different after placebo. These variables were not altered by Cit in women. Adjusting for baseline diastolic blood pressure removed (P = 0.10) the difference in FBF and FVC following Cit in men. These results indicate that l-citrulline has a modest effect of improving muscle blood flow during submaximal exercise in older men.

The influence of physical characteristics on the resting energy expenditure of youth: A meta-analysis.

OBJECTIVE: To examine the literature on resting energy expenditure (REE) of youth and determine the influence of age, sex, BMI, and body composition on REE. METHODS: A literature search was conducted using PubMed, BIOSIS Previews, NTIS, EMBASE, MEDLINE, and Pascal databases for studies with data on resting metabolic rate, REE, resting oxygen uptake (or VO2 ) in healthy children, youth, or adolescents (age = 1-18 years). Over 200 publications were identified; sixty-one publications met criteria and were included in the meta-analyses, resulting in 142 study population estimates (totaling 5,397 youth) of REE. RESULTS: Pooled mean was 1414 kcal·day-1 with a significant and moderate-to-high between-study heterogeneity [Q(140) = 7912.42, P < 0.001; I2 = 98.97%]. A significantly greater (P < 0.001) pooled mean kcal·day-1 was estimated for studies with male participants (1519 kcal·day-1 ) comparing to studies with female participants (1338 kcal·day-1 ). Age, height, and body mass resulted in the highest R2 of 86.4 for males and 83.9% for females. Fat free mass and body mass index (BMI) did not improve total R2 . CONCLUSIONS: These data suggest that using a linear equation including age, height, and body mass to estimate REE based on kcal·day-1 is more accurate than estimates based on body mass kcal·kg-1 ·h-1 . Further, if kcal·kg-1 ·h-1 is used, including a quadratic component for the physical characteristics improves the predictive ability of the equation. Regardless of the metric, separate equations should be used for each sex.

Sedentary Behavior, Physical Activity, and Bone Health in Postmenopausal Women.

The purpose of this study was to determine if bone health at the femoral neck (FN) and lumbar spine (LS) can be predicted from objectively-measured sedentary behavior and physical activity data in postmenopausal women. Waist-mounted ActiGraph GT1M and GT3X devices were used to quantify levels of sedentary and moderate-to-vigorous intensity behavior during a 7-day period in 44 older females. Bone health (normal and osteopenia/osteoporosis) of FN and LS was derived from T scores generated using dual energy x-ray absorptiometry. Binomial logistic regression analysis indicated that sedentary time and number of breaks in sedentary behavior were significant predictors of osteopenia/osteoporosis at the FN, but not at the LS. Adherence to physical activity guidelines was not a significant predictor of bone health at the FN or LS. Our findings suggest that more frequent interruptions in sedentary behavior are associated with improved bone health in postmenopausal women.

Objectively Measured Physical Activity Levels among Ethnic Minority Children Attending School-Based Afterschool Programs in a High-Poverty Neighborhood.

Ethnic minority children living in high poverty neighborhoods are at high risk of having insufficient physical activity (PA) during school days and, thus, the importance of school as a place to facilitate PA in these underserved children has been largely emphasized. This study examined the levels and patterns of PA in minority children, with particular focus on the relative contributions of regular physical education (PE) and school-based afterschool PA program in promoting moderate- and vigorous-intensity PA (MVPA) during school days. PA data were repeatedly measured using a Polar Active accelerometer across multiple school days (M = 5.3 days per child), from seventy-five ethnic minority children attending a Title I public elementary school in a high-poverty neighborhood in the US. The minutes and percentage of MVPA accumulated during school, PE, and afterschool PA program were compared to the current recommendations (≥30-min of MVPA during school hours; and ≥50% of MVPA during PE or afterschool PA program) as well as by the demographic characteristics including sex, grade, ethnicity, and weight status using a general linear mixed model that accounts for repeated observations. On average, children spent 41.6 mins (SE = 1.8) of MVPA during school hours and of those, 14.1 mins (SE = 0.6) were contributed during PE. The average proportion of time spent in MVPA during PE was 31.3% (SE = 1.3), which was significantly lower than the recommendation (≥50% of MVPA), whereas 54.2% (SE = 1.2) of time in afterschool PA program were spent in MVPA. The percentage of monitoring days meeting current recommendations were 69.5% (SE = 0.03), 20.8% (SE = 0.02), and 59.6% (SE = 0.03) for during school, PE, and afterschool PA program, respectively. Our findings highlighted that school-based afterschool PA, in addition to regular PE classes, could be of great benefit to promote PA in minority children during school days. Further research and practice are still needed to increase MVPA during school hours, particularly during PE classes.

Concurrent Associations of Physical Activity and Screen-Based Sedentary Behavior on Obesity Among US Adolescents: A Latent Class Analysis.

BACKGROUND: Independent associations of physical activity (PA) and sedentary behavior (SB) with obesity are well documented. However, little is known about the combined associations of these behaviors with obesity in adolescents. The present study examines the prevalence of concurrent levels of PA and SB, and their associations with obesity among US adolescents. METHODS: Data from a total of 12 081 adolescents who participated in the Youth Risk Behaviors Survey during 2012-2013 were analyzed. A latent class analysis was performed to identify latent subgroups with varying combined levels of subjectively measured PA and screen-based SB. Follow-up analysis examined the changes in the likelihood of being obese as determined by the Center for Disease Control and Prevention Growth Chart between latent subgroups. RESULTS: Four latent subgroups with varying combined levels of PA and SB were identified across gender. The likelihood of being obese was significantly greater for the subgroups featuring either or both Low PA or High SB when compared with High PA/Low SB across genders (odds ratio [OR] ranges, 2.1-2.7 for males and 9.6-23.5 for females). Low PA/High SB showed the greater likelihood of being obese compared to subgroups featuring either or both High PA and Low SB (OR ranges, 2.2-23.5) for female adolescents only. CONCLUSIONS: The findings imply that promoting sufficient levels of PA while reducing SB should be encouraged in order to reduce obesity risk among adolescents, particularly for males. The risk of obesity for female adolescents can be reduced by engaging in either high levels of PA or low levels of SB.

Physical Activity, Screen-Based Sedentary Behavior, and Sleep Duration in Adolescents: Youth Risk Behavior Survey, 2011-2013.

This study examined the concurrent associations of physical activity and screen-based sedentary behavior with sleep duration among adolescents by using data from the national Youth Risk Behavior Survey 2011-2013. Using latent class analysis, we identified 4 latent subgroups of adolescents with various levels of physical activity and screen-based sedentary behavior. The subgroup with high levels of physical activity and low levels of sedentary behavior generally showed greater odds of having sufficient sleep (≥8 hours/night) than the other subgroups. Findings imply that concurrent achievement of a high level of physical activity and low level of screen-based sedentary behavior is necessary to promote sufficient sleep among adolescents.