Commentary on Association of daily sitting time and leisure-time physical activity with body fat among U.S. adults

<正>In their study,association of daily sitting time and leisure-time physical activity (LTPA) with body fat among U.S.Adults,Liao et al.¹ analyzed data from the 2011-2018 National Health and Examination Survey to examine associations between h/day sitting,meeting (or not meeting) the U.S.Physical Activity Guidelines of≥150 min/week of moderate-and vigorous-intensity LTPA,and combinations of sitting time and LTPA on totaland trunk percent body fat (BF%).     

Leukocyte telomere length and mortality among U.S. adults: Effect modification by physical activity behaviour

The purpose of this study was to examine the association between leukocyte telomere length (LTL) and mortality (outcome variable), with consideration by physical activity behaviour. Data from the 1999–2002 National Health and Nutrition Examination Survey were employed (N = 6,611; 20–85 yrs), with follow-up mortality assessment through 31 December 2006. DNA was extracted from whole blood to assess LTL via quantitative polymerase chain reaction. Compared to those in the first LTL tertile, the adjusted hazard ratio for all-cause mortality for those in the 2^nd and 3^rd LTL tertiles, respectively, was 0.82 (95% CI: 0.60–1.12; P = .22) and 0.76 (95% CI: 0.50–1.14; P = .18). However, after adjustments, LTL tertile 3 (vs. 1) was associated with all-cause mortality (HR = 0.37; 95% CI: 0.14–0.93; P = .03) for those who engaged in moderate-intensity exercise. Similarly, LTL was associated with CVD-specific mortality for those who engaged in moderate-intensity exercise (HR = 0.17; 95% CI: 0.04–0.73; P = .02). Longer telomeres are associated with increased survival, particularly among men and those who are active, underscoring the importance of promotion of physical activity behaviour.     

Parental and peer influences on leisure-time physical activity in young adolescents.

Influence from parents and friends on adolescents' self-reported level of leisure-time physical activity was examined through measures of (a) perceived leisure-time physical activity of parents and best friend, (b) perceived direct support for physical activity from parents and friends, (c) direct help from parents in exercising vigorously, and (d) perceived value of physical activity of parents and friends. The present analysis included 904 students in western Norway (M age 13.3 years, SD 0.3) who took part in a health behavior survey, which included questions regarding physical activity. Students completed a confidential questionnaire at school. All four measures of influence were positively related to students' activity levels. None of the examined measures was clearly stronger than the other. Parental and peer physical activity level and parental and peer support for physical activity seem to influence the reported physical activity level of the respondents. The findings indicate that, by serving as models and supporters, significant others have an important impact in promoting physical activity in young adolescents.     

中美部分地区青少年参加体育活动状况的比较研究

通过对中美两国青少年参加体育活动状况的比较,得出几点启示,进而提出一些建议：①中国学校和家庭要逐渐走出应试教育的模式适当减轻学生的学业负担,尊重他们的爱好和兴趣,并为他们参加体育活动提供一定的条件。②青少年体育、娱乐、教育部门在制订计划时应保证男、女青少年有一系列平等的学习经历,包括发展青少年的身体素质和基本运动技能,这些有助于女孩子价值态度和抱负的形成。这些建议希望能为开展青少年的体育活动提供一点依据。     

Inter-participant variability in daily physical activity and sedentary time among male youth sport footballers: independent associations with indicators of adiposity and cardiorespiratory fitness

Participation in youth sport is assumed to promote and contribute towards more physically active lifestyles among children and adolescents. The aim of this study was to examine inter-participant variability in objectively measured habitual physical activity (PA) behaviours and sedentary time among youth sport participants and their implications for health. One-hundred-and-eighteen male youth sport footballers (Mean ± s = 11.72 ± 1.60) wore a GT3X accelerometer for 7 days. Average daily PA [min · day^?1, in light (LPA), moderate (MPA), vigorous (VPA) and combined moderate-to-vigorous (MVPA)] and sedentary time were calculated. Participants’ body mass index adjusted for age and sex (BMI–standard deviation score), per cent body fat (BF%), waist circumference and cardiorespiratory fitness were assessed. Results revealed that variability in daily PA behaviours and sedentary time (min · day^?1) was associated with BMI–standard deviation score [VPA (?), MVPA (?)], BF% [sedentary time (+), VPA (?), MVPA (?)], waist circumference [sedentary time (+), LPA (?)] and cardiorespiratory fitness [sedentary time (?), MPA (+), VPA (+), MVPA (+)]. Whilst sedentary time and MVPA were not related to health outcomes independent of one another, associations with markers of adiposity and cardiorespiratory fitness were stronger for sedentary time. Sedentary time was also significantly positively related to waist circumference independent of VPA. Results demonstrate inter-participant variability in habitual PA and sedentary time among youth sport participants which holds implications for their health. Thus, promoting PA and, in particular, reducing sedentary time may contribute towards the prevention of adverse health consequences associated with a physically inactive lifestyle for children and adolescents active in the youth sport context.     

Associations of subjective social status with accelerometer-based physical activity and sedentary time among adolescents

This study examined the associations of subjective social status (SSS) with physical activity (PA) and sedentary time (ST) among adolescents. The study population consisted of 420 Finnish adolescents aged 13 to 14 years. The adolescents reported their own SSS within their school (school SSS) and their family’s social position within society (society SSS) based on the youth version of the Subjective Social Status Scale. Adolescents’ moderate- to vigorous-intensity physical activity (MVPA) and ST were measured objectively by accelerometers and analyzed separately for the whole day and the school day. The associations between SSS and MVPA and ST outcomes were analyzed using multilevel modeling. School SSS was positively associated with whole-day MVPA and negatively associated with school-time ST. Society SSS was not significantly associated with objectively measured MVPA or ST. Both MVPA and ST are important behavioral determinants of health. As an important correlate of MVPA and ST, school SSS should be addressed by providers when discussing obesity risk and healthy behaviors with adolescents.     

Exploring self-perceptions and social influences as correlates of adolescent leisure-time physical activity

This study examined adolescent leisure-time physical activity correlates using the expectancy-value (EV) model. Adolescents (N = 857) completed questionnaires to assess competence and value self-perceptions, social influences, and physical activity. Direct and indirect effects of self-perceptions and parent and best friend influences on physical activity were explored using structural equation modeling. Measurement models were a good fit to the data and gender invariance was supported. The structural mediation model was a reasonable fit to the data, whereby the indirect effects of parents and peers and the direct effects of competence beliefs and values together accounted for 49% of the variance in physical activity. In this model, the pattern of relationships was similar for adolescent males and females. Findings supporting the EV model provide theoretical and practical implications for understanding adolescent physical activity.     

Association of leisure time and occupational physical activity with obesity and cardiovascular risk factors in Chile

ABSTRACT

The aim of this study was to investigate the association between physical activity (PA), both occupational (OPA) and during leisure time (LTPA), with obesity and cardiovascular risk factors in Chilean adults. 5,157 participants from the Chilean National Health Survey 2009–2010 were included in this study. OPA and LTPA levels were assessed using the Global Physical Activity Questionnaire. The association between both PA with obesity and cardiovascular risk factors was determined using logistic regression. Our findings showed a significant trend between higher LTPA and lower odds for obesity (OR 0.64 [95% CI: 0.53; 0.76], central obesity 0.52 [0.44; 0.61]) and other cardiovascular risk factors including diabetes (OR: 0.72 [0.55; 0.94]), hypertension (OR: 0.59 [0.50; 0.71]) and metabolic syndrome (OR: 0.62 [0.50; 0.78]). In contrast, OPA was only associated with lower odds of diabetes (OR: 0.79 [0.65; 0.98]) and hypertension (0.85 [0.74; 0.98]). In conclusion, LTPA was associated with a lower risk of all major cardiovascular risk factors, whereas OPA was only associated with a lower risk of diabetes and hypertension.     

The impact of the coronavirus disease 2019 pandemic on physical activity in U.S. children

BackgroundDaily moderate-to-vigorous physical activity (MVPA) is vital to the physical, mental, and social well-being of children. Early restrictions during the coronavirus disease 2019 (COVID-19) pandemic included the closure of schools and physical activity (PA) amenities across the US. This study aimed to examine the impact of the pandemic on the PA and play behavior of U.S. children and to provide evidence-based recommendations to improve their PA.MethodsA cross-sectional, online, parent-reported survey was conducted of children aged 3–18 years between April and June 2020 to assess light PA and MVPA using a modified Godin Leisure-Time Exercise Questionnaire. Additional items included family/child socioeconomic demographics, child adaptability to the pandemic, and community access. The survey was shared through social media and snowball sampling distribution.ResultsAnalysis of 1310 surveys indicated child PA scores declined significantly during the pandemic (from 56.6 to 44.6, max 119, p < 0.001). Specifically, MVPA score decreased (from 46.7 to 34.7, max 98, p < 0.001) while light PA remained the same. Age-based changes were seen in the quantity, variety, and intensity of PA, with the lowest pandemic-related impact seen in preschoolers and the highest in high schoolers (–4.7 vs. –17.2, p < 0.001). Community-based peer PA decreased across all age groups.ConclusionThis study shows decreased PA levels in U.S. children, according to parent reporting, during the COVID-19 pandemic. Recommendations for community leaders, educators, and parents to improve PA in children are provided. With continued spread of COVID-19, these results and recommendations may be imperative to the physical well-being of U.S. children.     

Associations between aerobic and muscle-strengthening physical activity,sleep duration,and risk of all-cause mortality: A prospective cohort study of 282,473 U.S. adults

PurposeTo examine the joint associations between meeting guidelines for physical activity (PA) and sleep duration and all-cause mortality risk among adults.MethodsParticipants were adults (n = 282,473) aged 18–84 years who participated in the 2004–2014 U.S. National Health Interview Survey. Mortality status was ascertained using the National Death Index through December 2015. Self-reported PA (Active: meeting both aerobic (AER) and muscle-strengthening (MSA) guidelines, AER only (AER), MSA only (MSA), or not meeting either AER or MSA (Inactive)) and sleep duration (Short, recommended (Rec), or Long) were classified according to guidelines, and 12 PA–sleep categories were derived. Adjusted hazard ratios and 95% confidence intervals (95%CIs) for all-cause mortality risk were estimated using Cox proportional hazards regression models.ResultsA total of 282,473 participants (55% females) were included; 18,793 deaths (6.7%) occurred over an average follow-up of 5.4 years. Relative to the Active-Rec group, all other PA-sleep groups were associated with increased mortality risk except for the Active-Short group (hazard ratio = 1.08; 95%CI: 0.92–1.26). The combination of long sleep with either MSA or Inactive appeared to be synergistic. For a given sleep duration, mortality risk progressively increased among participants classified as AER, MSA, and Inactive. Within each activity level, the mortality risk was greatest among adults with long sleep.ConclusionRelative to adults meeting guidelines for both PA and sleep duration, adults who failed to meet guidelines for both AER and muscle strengthening PA and who also failed to meet sleep duration guidelines had elevated all-cause mortality risks. These results support interventions targeting both PA and sleep duration to reduce mortality risk.     

Park use and physical activity among adolescent girls at two time points

This longitudinal study described park usage and assessed the contribution of parks to moderate to vigorous physical activity (MVPA) among adolescent girls. High school girls from California (n = 131) and Minnesota (n = 134) wore a global positioning system (GPS) monitor and accelerometer for 6 consecutive days at two time points, one year apart. Park visits were classified by linking the GPS, accelerometer, and park and built environment data around home and school locations into a geographic information system. At baseline, 20% of girls visited a park at least once (mean 0.1 times/day), which was similar one year later (19%, mean 0.1 times/day). Girls lived a mean Euclidean distance of 0.2 miles to the nearest park at both times. Among all park visits, the mean Euclidean distance of the park visited was 4.1 (baseline) and 3.9 miles (follow-up). The average duration of park visits was higher at baseline (63.9 minutes) compared to follow-up (38.4 minutes). On days when a park was visited, MVPA was higher than on days when a park was not visited. On average, 1.9% (baseline) and 2.8% (follow-up) of MVPA occurred in parks. In this study, parks were an under-used resource for adolescent girls, particularly for MVPA.     

The mediating role of intention and stages of change in physical activity among adults with physical disabilities: an integrative framework

The study's purpose was to identify the mediating role of intention and the stages of change (SOC) in physical activity (PA) over a 6-month period using two models (theory of planned behavior [TPB] and TPB/SOC). Participants were 143 adults with physical disabilities (70.68% response rate; M age = 46.03). The TPB constructs, SOC (time 1), and PA (time 2) were assessed using standardized self-report questionnaires. Based on path analyses, attitude had the highest effect on intention and SOC followed by perceived behavioral control within both well-fit models. The variance in PA explained by the first (TPB) and second (TPB/SOC) models was 16% and 28% respectively. In the just identified model of TPB/SOC, the direct effect of SOC on physical activity remained strong (gamma(soc.pa) = .45) and SOC approached full mediation through attitude. Health promotion interventions need to include both intention and behavior elements (SOC) reinforcing increased PA value and barrier elimination.     

Perceptions of the physical environment,stage of change for physical activity,and walking among Australian adults

Data for this study were from a population survey of 1,200 adults ages 40-60 years, sampled from the Illawarra region of New South Wales. Questionnaire items on perceptions of the environment were factor analyzed into: Aesthetic Environment and Practical Environment. For both factors, those in the Contemplation stage had more negative views of the environment than those in Maintenance. Those who walked for 0-20 min/week held more negative perceptions of their environment than those who walked for 21-120 min/week and those who walked for > 120 min/week. The health promotion implications of these findings are that environments perceived as attractive and as providing convenient access to services and facilities may influence motivational readiness for physical activity and time spent walking.     

Weekday and weekend patterns of physical activity and sedentary time among Liverpool and Madrid youth

Abstract

Levels of physical inactivity and sedentary behaviour among English and Spanish youth are high and vary within different regions of each country. Little though is known about these during specific periods of the day. The purpose of this study was to describe physical activity (PA) and sedentary time during segments of the day and week, and compare these critical contexts between youth in the Liverpool and Madrid areas of England and Spain, respectively. PA was objectively assessed in 235 Liverpool- and 241 Madrid youth (aged 10–14 years) who wore accelerometers for seven consecutive days. Minutes of sedentary time, moderate PA, vigorous PA and moderate-to-vigorous physical activity (MVPA) were calculated for weekdays, weekend days, school time, non-school time and after-school. Between-country differences were analysed using analysis of covariance (ANCOVA). Madrid youth spent significantly more time in sedentary activities than their Liverpool counterparts. Madrid youth engaged in more minutes of moderate intensity physical activity (MPA) than Liverpool youth during weekdays, school time and non-school time (P<0.01). Liverpool children recorded more time in vigorous physical activity (VPA) than Madrid peers during week days and weekend days (P<0.01) and during school time and after-school periods (P <0.01). The MVPA was significantly higher among Madrid youth during non-school time (P<0.01). Around 25% of all youth achieved recommended levels of MVPA. Low levels of MVPA and systematic differences in sedentary time, MPA and VPA exist between Liverpool and Madrid youth. Interventions targeted at the least-active children during weekends, after-school and non-school periods within the cultural contexts common to each city are required.     

Prevalence and correlates of physical fitness testing in U.S. schools--2000

Because of the perceived lack of youth physical fitness and/or concerns for increased obesity, physical education teachers are interested in youth fitness and physical activity levels. Statewide mandates are being developed that require school-based teachers to complete physical fitness testing. Data from the nationally representative School Health Policies and Programs Study 2000 were analyzed to investigate the prevalence of fitness testing and the professional characteristics of fitness test users. Data were collected with teachers of either randomly selected classes in elementary schools and randomly selected required physical education courses in middle/junior high and senior high schools (N = 1,564). The prevalence of fitness test use is 65% across all school levels. Variables associated with physical fitness test usage were professionally oriented. Results showed that teachers in secondary schools (odds ratio [OR] = 2.25, 95% confidence interval [CI] = I.18-4.27), those with degrees in physical education/kinesiology-related disciplines (OR = 2.01, 95% CI = 1.11-3.63), and those who had completed staff development on physical fitness testing (OR = 3.22, 95% CI = 1.86-5.60) were more likely than respondents without these characteristics to engage in physical fitness testing. Results changed little when separate analyses were conducted for classes/courses in districts requiring versus not requiring fitness testing. Financial variables, including fitness-oriented facilities available, metropolitan location, and discretionary expenditures per student, were not associated with fitness test use. Results provided national prevalence of school-based physical fitness testing use in the U. S. and conveyed information about those who currently use physical fitness tests.     

Physical activity, nutrition, screen time and sleep associated with body weight and physical condition in young children

The aim of this cross-sectional study was to explore the possible relationship between (un)healthy behaviour and (over)weight and physical condition in families with young children (4–7 years), in a village (30,000 inhabitants) in the eastern part of the Netherlands, close to Germany. It is one of two pilot studies as a precursor of a cross-border project including six Dutch and six German villages, to counteract physical inactivity and possible future metabolic problems. In total, 459 children of five elementary schools and their parents were included. Parents were requested to fill in a questionnaire on the nutritional, physical, sedentary, and sleeping behaviour of their child. Relevant background characteristics were obtained and lifestyle classifications were made. At school, the children's height and weight (body mass index (BMI)) were measured, as well as their physical condition (two tests) and basic motor abilities (four physical exercise tests). The relationship between the standardized BMI z-scores and physical condition test scores, and nutritional, physical, sedentary and sleeping habits was analysed using independent sample t-test, bivariate correlation analysis and multiple regression analysis. Latent class analysis was used to identify clusters of people based on their nutritional, physical and sleep habits. Of the parents, 376 (82?%) were willing to fill out the questionnaire. High birth weight and a high BMI of the mother and/or father correlated with a higher BMI of the child (ρ?=?0.28, p?<?0.001; ρ?=?0.13, p?=?0.016; and ρ?=?0.23, p?<?0.001, respectively). Daily playing outside, eating small cookies (compared with large cookies) and no sleeping problems (no waking up during the night) were related to low BMI levels (no overweight) [ρ?=???0.14, p?=?0.005; ρ?=???0.12, p?=?.020; t(364)?=?1.81, p?=?0.072 (trend), respectively]. Daily playing outside (frequency and duration) and being a member of a sports club were related to positive scores on the physical condition tests [ρ?=?0.20, p?<?0.001; t(365)?=???2.99, p?=?0.003, respectively]. High levels of television (TV) watching and general sleeping problems were related to a less optimal physical condition [ρ?=???0.09, p?=?0.076 (trend); and ρ?=???0.10, p?=?0.059 (trend), respectively]. A latent class analysis revealed three clusters: 46?% of the sample belonged to the ‘healthy group’ concerning nutrition, sedentary lifestyle and TV/personal computer (PC) use; 17?% to the ‘less healthy’ group and 37?% to a group with nutrition and physical activity habits close to the healthy group, but with low conditional probabilities for the sleeping items. Conducting a pilot study before the start of a binational intervention study gives a blueprint for the final questionnaire, and clues for tailored interventions in the schools, as proposed in the approach of ‘Gesunde Kinder in gesunden Kommunen’ (GKGK). The results of a latent class analysis underscore that interventions should exist of a multi-component strategy, focusing on promoting physical activity, healthy nutrition habits and appropriate sleep.     

Aerobic fitness and physical activity are inversely associated with body fat,dyslipidemia and inflammatory mediators in children and adolescents living with HIV

This study aimed to investigate if moderate to vigorous physical activity (MVPA) and aerobic fitness are associated with cardiovascular risk factors in HIV+ children and adolescents. Sixty-five children and adolescents (8 to 15 years) provided minutes of MVPA measured by accelerometers and peak oxygen uptake (peak VO₂) by breath-by-breath respiratory exchange. Cardiovascular risk factors were characterized by body fat, blood pressure, total cholesterol, HDL-c, LDL-c, triglycerides, glucose, insulin, C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α) and carotid intima-media thickness. Results indicated that higher MVPA was associated with lower values of total (β = ?3.566) and trunk body fat (β = ?3.495), total cholesterol (β = ?0.112) and LDL-c (β = ?0.830). Likewise, higher peak VO₂ was associated with lower total (β = ?0.629) and trunk body fat values (β = ?0.592) and levels of CRP (β = ?0.059). The physically active participants had lower total cholesterol (?24.4 mg.dL^?1) and LDL-c (?20.1 mg.dL^?1) compared to participants judged to be insufficiently active. Moreover, participants with satisfactory peak VO? showed lower total (?4.1%) and trunk (?4.3%) body fat, CRP (?2.3 mg.L^?1), IL-6 (?2.4 pg.mL^?1) and TNF-α (?1.0 pg.mL^?1) compared to low peak VO₂ peers. High levels of MVPA and aerobic fitness may prevent developing of cardiovascular risk factors in children and adolescents HIV+.     

Social support and physical activity participation among healthy adults: a systematic review of prospective studies

The objective of this review was to determine the direction and strength of the prospective relationship between social support and PA among healthy adults. A systematic review was conducted; including studies up until December 2015, in the following databases: Ovid MEDLINE, EMBASE, PsychINFO, SPORTDiscus, and Scopus. Published English and French written studies were included if the reported study used a longitudinal design; examined the relationship between social support and PA over at least two intervals; and assessed a sample of healthy adults between 18–65 years of age. Two reviewers independently extracted study information and independently assessed the risk of bias in each study. The initial search yielded a total of 2892 citations, and 20 studies were included in the review. Follow-up period ranged from 2 weeks to 10 years. Irrespective of the type and source of support, the strength and direction of the association between social support and PA was inconsistent across studies, with effect sizes ranging from small to large and from negative to positive. Based on meta-analysis, there was a small positive association between support for PA from friends and future PA. Researchers are encouraged to continue to conduct longitudinal studies to better understand the relationship between social support and PA.