Higher screen time is associated with overweight,poor dietary habits and physical inactivity in Brazilian adolescents,mainly among girls

Objectives: To analyse the associations between high screen time and overweight, poor dietary habits and physical activity in adolescents according to sex. Methods: The study comprised 515 boys and 716 girls aged 14–17 years from Londrina, Brazil. Nutritional status (normal weight or overweight/obese) was assessed by calculating the body mass index. Eating habits and time spent in physical activity were reported using a questionnaire. The measurement of screen time considered the time spent watching television, using a computer and playing video games during a normal week. Associations between high screen time and dependent variables (nutritional status, eating habits and physical activity levels) were assessed by binary logistic regression, adjusted for sociodemographic and lifestyle variables. Results: Most adolescents (93.8% of boys and 87.2% of girls) spent more than 2 hours per day in screen-time activities. After adjustments, an increasing trend in the prevalence of overweight and physical inactivity with increasing time spent on screen activities was observed for both sexes. Screen times of >4 hours/day compared with <2 hours/day were associated with physical inactivity, low consumption of vegetables and high consumption of sweets only in girls and the consumption of soft drinks in both sexes. Conclusions: The frequency of overweight and physical inactivity increased with increasing screen time in a trending manner and independently of the main confounders. The relationship between high screen time and poor eating habits was particularly relevant for adolescent girls.     

Accelerometer and GPS Data to Analyze Built Environments and Physical Activity

ABSTRACT

Purpose: Most built environment studies have quantified characteristics of the areas around participants’ homes. However, the environmental exposures for physical activity (PA) are spatially dynamic rather than static. Thus, merged accelerometer and global positioning system (GPS) data were utilized to estimate associations between the built environment and PA among adults. Methods: Participants (N = 142) were recruited on trails in Massachusetts and wore an accelerometer and GPS unit for 1–4 days. Two binary outcomes were created: moderate-to-vigorous PA (MVPA vs. light PA-to-sedentary); and light-to-vigorous PA (LVPA vs. sedentary). Five built environment variables were created within 50-meter buffers around GPS points: population density, street density, land use mix (LUM), greenness, and walkability index. Generalized linear mixed models were fit to examine associations between environmental variables and both outcomes, adjusting for demographic covariates. Results: Overall, in the fully adjusted models, greenness was positively associated with MVPA and LVPA (odds ratios [ORs] = 1.15, 95% confidence interval [CI] = 1.03, 1.30 and 1.25, 95% CI = 1.12, 1.41, respectively). In contrast, street density and LUM were negatively associated with MVPA (ORs = 0.69, 95% CI = 0.67, 0.71 and 0.87, 95% CI = 0.78, 0.97, respectively) and LVPA (ORs = 0.79, 95% CI = 0.77, 0.81 and 0.81, 95% CI = 0.74, 0.90, respectively). Negative associations of population density and walkability with both outcomes reached statistical significance, yet the effect sizes were small. Conclusions: Concurrent monitoring of activity with accelerometers and GPS units allowed us to investigate relationships between objectively measured built environment around GPS points and minute-by-minute PA. Negative relationships between street density and LUM and PA contrast evidence from most built environment studies in adults. However, direct comparisons should be made with caution since most previous studies have focused on spatially fixed buffers around home locations, rather than the precise locations where PA occurs.     

Effects of the Instructional Set in the Bandwidth Feedback Paradigm on Motor Skill Acquisition

ABSTRACT

Purpose: This study examined the relationships between the Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1) and resting heart rate variability (HRV) and submaximal 5?-5? test derived measures in novice male soccer players. Methods: Forty players (11.54 ± 0.58 years) from a soccer academy participated in this study, performing physical tests on two different days, separated by 48 h, as follows: (day 1) resting HRV and Yo-Yo IR1 test, and (day 2) anthropometric assessments (for peak height velocity assessment [PHV]) and the 5?-5? test. The Pearson product-moment correlation coefficient was used to determine the correlations between Yo-Yo IR1 performance and the remaining variables. A partial correlation analysis was further performed using age, stature, body mass, distance to PHV, and age at PHV as “confounders.” Results: The highest correlation score was observed between Yo-Yo IR1 performance and resting HRV, when the absolute age was used as confounder (r = 0.72; p < .05). Conclusions: We observed that a practical measure of parasympathetic activity at rest is largely associated with performance obtained during a traditional intermittent endurance performance test.     

Impact of a physical education-based behavioural skill training program on cognitive antecedents and exercise and sport behaviour among adolescents: a cluster-randomized controlled trial

ABSTRACT

Background: School-based physical education has been associated with a multitude of potential learning outcomes. Representatives of a public health perspective suggest that promoting physical activity in and outside the context of school is an important endeavour. While the importance of behavioural skill training to improve (motor) learning is well documented in both general and physical education, the promotion of behavioural skills to foster physically active lifestyles constitutes a rather neglected area in physical education research.

Purpose: To examine whether a standardized physical education-based behavioural skill training program has the potential to positively impact on adolescents’ self-reported exercise and sport participation, as well as cognitive antecedents involved in the regulation of exercise and sport behaviour.

Research design: Cluster-randomized controlled trial.

Methods: A sample of 143 secondary school students (50% girls, aged 14–18 years) attending academic high schools in German-speaking Switzerland were assigned class-wise to the intervention (behavioural skill training) and control condition (conventional physical education lessons). Data were assessed prior and after completion of the 7-week intervention program, which was composed of four 20-min lessons and two reflection phases. Exercise and sport behaviour and cognitive antecedents (exercise/sport intention, motivation, implementation intentions, coping planning, self-efficacy) were assessed via self-reports. A multilevel mixed effects linear regression procedure was used to test the main hypotheses. The regression analyses were adjusted for clustering of school classes, and controlled for baseline levels of the outcome measure and potential confounders.

Results: Compared to a control condition, the intervention program resulted in significant improvements with regard to introjected motivation (p?<?.05), coping planning (p?<?.001) and self-efficacy (p?<?.01). The intervention also had a positive impact on adolescents’ self-reported sport/exercise behaviour (p?<?.001). Improvements in exercise/sport intention (p?<?.05), coping planning (p?<?.01), and self-efficacy (p?<?.01) were associated with increased levels of self-reported exercise/sport participation.

Conclusion: Behavioural skill training as part of compulsory physical education has the potential to improve cognitive antecedents of exercise and sport behaviour and to foster adolescents’ exercise and sport participation. Enhancing behavioural skills might be one way in which school physical education can contribute to the creation of more physically active lifestyles among adolescents.     

Influence of physical fitness on cognitive and academic performance in adolescents: A systematic review from 2005–2015

Background: The aim of this systematic review was to investigate the association of different components of physical fitness on cognitive performance (CP) and academic performance (AP) in adolescents, taking into account potential confounders. Method: Studies were identified in four databases (Pubmed, SportDiscus, Web of Science, and ProQuest) from January 2005 through to January 2015. A total of 21 articles met the inclusion criteria. Results: 8 studies showed association between physical fitness and CP, and 11 studies with AP. Cardiorespiratory fitness, speed-agility, motor coordination, and perceptual-motor skill are the highest measures associated with CP and AP. However, the findings on strength and flexibility are unclear. Finally, 62% of the 21 studies used confounders. The most controlled confounder were socioeconomic status, fatness, pubertal status, sex, and age. Conclusion: Fitness is associated with higher CP and AP. More research is needed in order to understand the causes of the differential effect of physical fitness components on CP and AP.     

Objectively measured sedentary time and academic achievement in schoolchildren

This study aimed to evaluate the relationship between objectively measured total sedentary time and academic achievement (AA) in Portuguese children. The sample comprised of 213 children (51.6% girls) aged 9.46 ± 0.43 years, from the north of Portugal. Sedentary time was measured with accelerometry, and AA was assessed using the Portuguese Language and Mathematics National Exams results. Multilevel linear regression models were fitted to assess regression coefficients predicting AA. The results showed that objectively measured total sedentary time was not associated with AA, after adjusting for potential confounders.     

Reliability of a measurement technique for achilles tendon length

ABSTRACT

Recently, there has been an increasing amount of literature dealing with new methods of Achilles tendon (AT) length measurement. However, most of these studies measured the AT length between the calcaneus and medial head of the gastrocnemius and the reliability of such a measurement has not been satisfactorily presented. The purpose of this study was to determine the reliability of the measurement of AT length within and between sessions. AT length was measured by using a combination of ultrasound imaging and optoelectronic stereophotogrammetry. Nineteen healthy athletes visited the lab on six different days where the AT length was measured on both lower extremities: 1) from the calcaneus to the mid-point of the medial and lateral heads of the gastrocnemius; and 2) from the calcaneus to the soleus musculotendinous attachment. The reliability results indicated high intraclass correlation coefficients (ICC > 0.8), a low typical error (< 0.6) and a standard error of measurement (SEM < 5.5 mm) for all measured AT lengths on within and between sessions. This non-invasive reliable measurement method may be recommended for sport science research purposes.     

Physical activity and chronic back conditions: A population-based pooled study of 60,134 adults

BackgroundLittle is known about the association between different types of physical activity (PA) and chronic back conditions (CBCs) at the population level. We investigated the association between levels of total and type-specific PA participation and CBCs.MethodsThe sample comprised 60,134 adults aged ≥16 years who participated in the Health Survey for England and Scottish Health Survey from 1994 to 2008. Multiple logistic regression models, adjusted for potential confounders, were used to examine the association between total and type-specific PA volume (walking, domestic activity, sport/exercise, cycling, football/rugby, running/jogging, manual work, and housework) and the prevalence of CBCs.ResultsWe found an inverse association between total PA volume and prevalence of CBCs. Compared with inactive participants, the fully adjusted odds ratio (OR) for very active participants (≥15 metabolic equivalent h/week) was 0.77 (95% confidence interval (CI): 0.69–0.85). Participants reporting ≥300 min/week of moderate-intensity activity and ≥75 min/week of vigorous-intensity activity had 24% (95%CI: 6%–39%) and 21% (95%CI: 11%–30%) lower odds of CBCs, respectively. Higher odds of CBCs were observed for participation in high-level manual domestic activity (OR = 1.22; 95%CI: 1.00–1.48). Sport/exercise was associated with CBCs in a less consistent manner (e.g., OR = 1.18 (95%CI: 1.06–1.32) for low levels and OR = 0.82 (95%CI: 0.72–0.93) for high levels of sport/exercise).ConclusionPA volume is inversely associated with the prevalence of CBCs.     

Peak power output provides the most reliable measure of performance in prolonged intermittent-sprint cycling

Abstract

The aims of this study were to determine the reliability of an intermittent-sprint cycling protocol and to determine the efficacy of one practice session on main trials. Eleven men, moderately trained team-sport athletes, completed three visits to the laboratory involving a graded-exercise test and practice session and two trials of a Cycling Intermittent-Sprint Protocol separated by three days. Data for practice and main trials were analysed using typical error of measurement, intra-class correlation and least-products regression to determine reliability. Typical error of measurement (expressed as a coefficient of variation) and intra-class correlation for peak power output from all 20 sprints for trial 1 and trial 2 were 2.9 ± 12.8% (95% confidence interval: 2.0–5.0%) and 0.96 (95% confidence interval: 0.85–0.99), respectively. Typical errors of measurement and intra-class correlation for mean power output for all 20 sprints for trials 1 and 2 were 4.2 ± 11.9% (95% confidence interval: 2.9–7.4%) and 0.90 (95% confidence interval: 0.66–0.97), respectively. The results suggest that peak power output provides a more reliable measure than mean power output. The Cycling Intermittent-Sprint Protocol provides reliable measures of intermittent-sprint performance.     

The relationships between step count and all-cause mortality and cardiovascular events: A dose–response meta-analysis

BackgroundA goal of 10,000 steps per day is widely advocated, but there is little evidence to support that goal. Our purpose was to examine the dose–response relationships between step count and all-cause mortality and cardiovascular disease risk.MethodsCochrane Central Register of Controlled Trials, EMBASE, OVID, PubMed, Scopus, and Web of Science databases were systematically searched for studies published before July 9, 2021, that evaluated the association between daily steps and at least 1 outcome.ResultsSixteen publications (12 related to all-cause mortality, 5 related to cardiovascular disease; and 1 article contained 2 outcomes: both all-cause death and cardiovascular events) were eligible for inclusion in the meta-analysis. There was evidence of a nonlinear dose–response relationship between step count and risk of all-cause mortality or cardiovascular disease (p = 0.002 and p = 0.014 for nonlinearity, respectively). When we restricted the analyses to accelerometer-based studies, the third quartile had a 40.36% lower risk of all-cause mortality and a 35.05% lower risk of cardiovascular event than the first quartile (all-cause mortality: Q1 = 4183 steps/day, Q3 = 8959 steps/day; cardiovascular event: Q1 = 3500 steps/day, Q3 = 9500 steps/day; respectively).ConclusionOur meta-analysis suggests inverse associations between higher step count and risk of premature death and cardiovascular events in middle-aged and older adults, with nonlinear dose–response patterns.     

Validity and reliability of a new method for measuring putting stroke kinematics using the TOMI® system

Abstract

The purpose of this study was to determine the validity and reliability of a new method for measuring three-dimensional (3D) putting stroke kinematics using the TOMI® device. A putting robot and a high-speed camera were used to simultaneously collect data for the validity evaluation. The TOMI® device, when used in conjunction with standard 3D coordinate data processing techniques, was found to be a valid and reliable method for measuring face angle, stroke path, putter speed, and impact spot at the moment of ball contact. The validity of the TOMI® measurement system was quantified using the 95% limits of agreement method for each aforementioned variable. The practical significance of each validity score was assessed by incorporating the maximum estimated measurement error into the stroke of the putting robot for 10 consecutive putts. All putts were executed from a distance of 4 m on a straight and flat synthetic putting surface. Since all putts were holed successfully, the measurement error for each variable was deemed to be negligible for the purposes of measuring putting stroke kinematics. The influence of key kinematic errors, at impact, on the outcome of a putt was also determined.     

Domain-specific physical activity and health-related quality of life in university students

Abstract

Information on the relationship between domain-specific physical activity (PA) and health-related quality of life (HRQoL) in the general population and specific groups is still scarce. The aim of this study was to determine the relationship between PA in work, transport, domestic and leisure-time domains and HRQoL among university students. PA and HRQoL were assessed in a random stratified sample of 1750 university students using the International Physical Activity Questionnaire – long form and 12-item Short Form Health Survey, respectively. The Spearman's rank correlations, adjusted for age, community size, personal monthly budget, body mass index, smoking habits and alcohol intake ranged from ?0.11 to 0.18 in female students and ?0.29 to 0.19 in male students. Leisure-time, domestic, transport-related PA and total PA were positively related to HRQoL. Inverse correlations with HRQoL were only found for work-related PA in male students. Multiple linear regression analysis showed that only leisure-time PA was related to the Physical Summary Component score (β = 0.08 for females and β = 0.10 for males, P < 0.05). Domain-specific PA levels were not significantly related to the Mental Component Summary score. To get a more comprehensive insight in the relationship between PA and HRQoL, future studies should not only analyse total PA levels but also domain-specific PA levels. The evidence on the positive relationship of leisure-time, transport and domestic PA with HRQoL can potentially be used to support evidence-based promotion of PA in a university setting, and as a hypothesis for future longitudinal studies on such potential causal relationships.     

踝关节小腿三头肌力臂非线性回归方程的探讨

用分段三次样条拟合计算了踝关节瞬时转动中心(简称瞬心)的位置,并根据肌力臂的定义,计算出不同踝关节角度时,小腿三头肌相对于瞬心的力臂。再按照统计学原理,对所得瞬心位置和肌力臂数据进行方差分析,利用多元非线性回归方法最终建立了肌力臂与踝关节形态参数及关节角度的非线性回归方程。     

Exercise and bone

Abstract

The aim of this study was to examine the interrelationship between aerobic fitness, body composition, and physical activity in 9- and 15-year-olds. The 270 participants were randomly selected from 18 primary and secondary schools in Iceland. Aerobic fitness was assessed by a graded exercise test on a bicycle ergometer. Body composition was estimated via: logarithm of sum of four skinfolds (log_e skinfolds), waist adjusted for height, and body mass index (BMI). Physical activity was measured with Actigraph activity monitors using total activity each day as the physical activity variable. Aerobic fitness was chosen as the primary outcome variable, body composition as the secondary variable, and physical activity as the tertiary variable. All the full models explained a similar proportion of fitness variance for both age groups (45–65%). Among the 15-year-olds, log_e skinfolds explained a significantly larger proportion of the fitness variance (54%) than waist adjusted for height (29%) and BMI (15%), but all the body composition variables explained a similar proportion of the fitness variance (35–42%) among the 9-year-olds. Physical activity explained a smaller proportion (0%) of the unadjusted variance in fitness for the 9-year-olds than for the 15-year-olds (19%). This group difference became non-significant (0% vs. 4%) when adjusting for log_e skinfolds but remained significant when controlling for waist adjusted for height (0% vs. 15%) and BMI (0% vs. 18%). Gender differences in aerobic fitness after puberty can largely be explained by gender differences in log_e skinfolds and physical activity. In conclusion, the interrelationship between fitness, body composition, physical activity, and gender is not the same among 9- and 15-year-olds.     

“The fouled player should not take the penalty himself”: An empirical investigation of an old German football myth

Abstract

In this study, we investigate the old German football myth that the fouled player should not take the resulting penalty himself, as he is at an increased risk of missing. Previous analyses are improved on as we adjust for potential confounders that might influence self-taking as well as successful penalty conversion. Our findings reveal some important predictors for self-taking but, somewhat surprisingly, neither self-taking nor any of the potential confounders predicts scoring a penalty kick.     

Measurement Schedules of Sprint Running

Abstract

Four measures of elapsed time were secured on a sample of 76 male physical education majors during a 50-yd. sprint. The subjects were timed during two sprints and measurements were secured at 20, 30, 40, and 50 yd. Ten different measurement schedules were developed from the four measurements. Data revealed that the greatest source of measurement error existed in the first 20 yd. of the sprint. The intraclass reliability estimates of the 10 measurement schedules ranged from .79 to .98.     

The reliability of force-velocity-power profiling during over-ground sprinting in children and adolescents

ABSTRACT

Anaerobic performance in youth has received little attention partly due to the lack of a “gold-standard” measurement. However, force-velocity-power (F-v-P) profiling recently showed high reliability and validity in trained adults. Therefore, the aim was to determine the reliability of F-v-P profiling in children and adolescents. Seventy-five children (60 boys, 15 girls; age: 14.1 ± 2.6 years) completed three 30 m sprints. Velocity was measured at 46.875 Hz using a radar device. The F-v-P profile was fitted to a velocity-time curve allowing instantaneous power variables to be calculated. Reliability was assessed using the intra-class correlation coefficient (ICC), coefficient of variation (CV), standard error of measurement (SEM) and smallest worthwhile change (SWC). High reliability was evident for absolute peak (P_peak) and mean power (P_mean), P_peak and P_mean expressed relative to body mass, peak and mean velocity, 30 m sprint time, peak horizontal force (F₀), relative F₀, mechanical efficiency index and fatigue rate (ICC: 0.75–0.88; CV: 1.9–9.4%) with time to peak power demonstrating moderate reliability (ICC: 0.50; CV: 9.5%). The F-v-P model demonstrated at least moderate reliability for all variables. This therefore provides a potential alternative for paediatric researchers assessing sprint performance and the underlying kinetics.     

A physically active lifestyle is related to a lower level of skin autofluorescence in a large population with chronic-disease (LifeLines cohort)

Background:Physical activity(PA)has substantial health benefits and is important in combatting chronic diseases,which have been associated with elevated levels of advanced glycation endproducts(AGEs).AGEs play a role in the aging process,and an association between PA and AGEs has been reported.We aimed to investigate the relationship between PA and AGE accumulation in a general population and in a population with chronic diseases.Methods:This large cross-sectional population study used data from adult participants in the LifeLines project,with participant information drawn from the LifeLines database as well data from patients with diabetes mellitus or renal and/or cardiovascular diseases.Tissue AGE accumulation was assessed non-invasively by skin-autofluorescence(SAF)using an AGE reader(DiagnOptics Technologies BV,Groningen,the Netherlands).PA was assessed using the short questionnaire to assess health-enhancing physical activity(SQUASH).Multivariate linear regression analyses were adjusted for age,body mass index,sex,and smoking status.Results:Data from 63,452 participants(general population n=59,177,chronic disease n=4275)were analyzed.The general population was significantly younger(43.58±11.77 years,mean±SD)and had significantly lower SAF(1.90±0.42 arbitrary units(AU))compared to the population with chronic disease(age:55.51±12.07 years;SAF:2.27±0.51 AU).In the group with chronic disease,more hours of moderate to vigorous physical activities per week were associated with lower SAF(β=-0.002,95%confidence interval(95%CI):-0.002 to-0.001).For the general population,there was no association between hours of moderate to vigorous activity and SAF(β=3.2×10^-5,95%CI:0.000-0.001,p=0.742).However,there was an association in the general population between total hours of PA per week and SAF(β=4.2×10^-4,95%CI:0.000-0.001,p<0.001),but this association was not found in the chronic disease population(β=-3.2×10^-4,95%CI:-0.001 to 0.000,p=0.347).Conclusion:Our study demonstrates that an inverse relationship exists between PA and AGE accumulation in the population with chronic disease.More hours of moderate to vigorous activity is associated a significantly decreased SAF.More PA is associated a lower SAF,even after for the established predictors(age,body mass index,smoking status,and sex).Our findings could help to promote health and prolong longevity.     

Description of a Low Cost Microcomputer System Interfaced to Exercise Stress Testing Equipment

Abstract

In recent years the classic Margaria step-test for anaerobic power has been largely replaced by bicycle ergometer tests, the most popular of these being the Wingate Anaerobic Test (WAnT). The purpose of this study was to examine the relationship between the WAnT and sprint-run times and to determine the influence of age and weight on the WAnT scores. The 56 male volunteers (age 10–15 years) recruited from a track club and junior high school represented a wide range of athletic abilities. Subjects were tested for anaerobic power (5 sec output) and capacity (30 sec output) using the Wingate test procedures. Wingate scores for anaerobic power and capacity were only moderately correlated with 50 yd dash times (r = ?.53 and ?.53) and with the 600 yd run (r = ?.26 and ?.29). Partial correlations between these variables were lower when age adjusted and higher when adjusted for body weight. Results of this study indicate that the Wingate anaerobic test is only a moderate predictor of dash or run times, but becomes a stronger predictor when WAnT scores are adjusted for body weight. The high correlation of the WAnT with body weight must be taken into account when comparing the anaerobic capacity of individuals. The standing long jump would be the preferred field test of sprint-related ability because of its simplicity, but the Wingate lest has the advantage of providing a quantitative measurement of anaerobic fitness.