Exploring the Adolescent Fall in Physical Activity: A 10-yr Cohort Study (EarlyBird 41)

Longitudinal associations of screen time, physical activity, and sleep duration with body mass index in U.S. youth

BACKGROUND

Youth use different forms of screen time (e.g., streaming, gaming) that may be related to body mass index (BMI). Screen time is non-independent from other behaviors, including physical activity and sleep duration. Statistical approaches such as isotemporal substitution or compositional data analysis (CoDA) can model associations between these non-independent behaviors and health outcomes. Few studies have examined different types of screen time, physical activity, and sleep duration simultaneously in relation to BMI.

METHODS

Data were baseline (2017-2018) and one-year follow-up (2018-2019) from the Adolescent Brain Cognitive Development Study, a multi-site study of a nationally representative sample of U.S. youth (N = 10,544, mean [SE] baseline age = 9.9 [0.03] years, 48.9% female, 45.4% non-White). Participants reported daily minutes of screen time (streaming, gaming, socializing), physical activity, and sleep. Sex-stratified models estimated the association between baseline behaviors and follow-up BMI z-score, controlling for demographic characteristics, internalizing symptoms, and BMI z-score at baseline.

RESULTS

In females, isotemporal substitution models estimated that replacing 30 min of socializing (β [95% CI] = -0.03 [-0.05, -0.002]), streaming (-0.03 [-0.05, -0.01]), or gaming (-0.03 [-0.06, -0.01]) with 30 min of physical activity was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing (-0.03 [-0.05, -0.01]), streaming (-0.02 [-0.03, -0.01]), or gaming (-0.02 [-0.03, -0.01]) with 30 min of sleep was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing with 30 min of gaming was associated with a lower follow-up BMI z-score (-0.01 [-0.03, -0.0001]). CoDA estimated that in males, a greater proportion of time spent in baseline socializing, relative to the remaining behaviors, was associated with a higher follow-up BMI z-score (0.05 [0.02, 0.08]). In females, no associations between screen time and BMI were observed using CoDA.

CONCLUSIONS

One-year longitudinal associations between screen time and BMI may depend on form of screen time, what behavior it replaces (physical activity or sleep), and participant sex. The alternative statistical approaches yielded somewhat different results. Experimental manipulation of screen time and investigation of biopsychosocial mechanisms underlying the observed sex differences will allow for causal inference and can inform interventions.

Adolescence is characterized by more sedentary behaviour and less physical activity even among highly active forager-farmers

Over 80% of adolescents worldwide are insufficiently active, posing massive public health and economic challenges. Declining physical activity (PA) and sex differences in PA consistently accompany transitions from childhood to adulthood in post-industrialized populations and are attributed to psychosocial and environmental factors. An overarching evolutionary theoretical framework and data from pre-industrialized populations are lacking. This cross-sectional study tests hypotheses from life history theory, that adolescent PA is inversely related to age, but this association is mediated by Tanner stage, reflecting higher and sex-specific energetic demands for growth and reproductive maturation. Detailed measures of PA and pubertal maturation are assessed among Tsimane forager-farmers (age: 7-22 years; 50% female, n = 110). Most Tsimane sampled (71%) meet World Health Organization PA guidelines (greater than or equal to 60 min/day of moderate-to-vigorous PA). Like post-industrialized populations, sex differences and inverse age-activity associations were observed. Tanner stage significantly mediated age-activity associations. Adolescence presents difficulties to PA engagement that warrant further consideration in PA intervention approaches to improve public health.

Availability of Recreation Facilities and Parks In Relation to Adolescent Participation in Organized Sports and Activity Programs

Most adolescents do not meet physical activity guidelines, so understanding facilitators and barriers is important. This study used surveys and geocoded location data to examine associations of availability of parks and recreation facilities with adolescent-reported participation in organized team sports and physical activity classes. The study was conducted with 928 adolescents aged 12-17 years, plus one parent/caretaker, recruited from two regions of the US. Adolescents' participation in teams and classes was positively associated with parents' perceptions of multiple available recreation environments, but not with objectively-measured availability. Having multiple nearby parks and recreation facilities may provide adolescents with more options for participating in preferred organized team sports and activity classes.

Cognitive-behavioral therapy and exercise training in adolescent females with elevated depression symptoms and at-risk for type 2 diabetes: Protocol for a randomized controlled trial

BACKGROUND

Adolescent-onset type 2 diabetes (T2D) is a major public health concern of growing proportions. Prevention, therefore, is critical. Unfortunately, standard-of-care treatment for T2D prevention (e.g., exercise training) show insufficient effectiveness and do not address key modifiable barriers (e.g., depression symptoms) to exercise engagement. Depression symptoms are associated with both poorer physical fitness and greater insulin resistance, the key risk factor in adolescent-onset T2D. Thus, a targeted prevention approach that addresses depression symptoms in combination with exercise training may offer a novel approach to mitigating T2D risk.

METHODS

This manuscript describes the design and study protocol for a multi-site, four-arm randomized controlled trial comparing the efficacy of group cognitive-behavioral therapy, group exercise training, and their combinations for the targeted prevention of worsening insulin resistance in N = 300 adolescent females at-risk for T2D with BMI ≥85th percentile and elevated depression symptoms. All four intervention arms will run in parallel and meet weekly for 1 h per week for 6-week to 6-week segments (12 weeks total). Outcomes are assessed at baseline, 6-week mid-treatment, 12-week follow-up, and 1-year follow-up.

RESULTS

The primary outcome is insulin resistance. Key secondary outcomes include insulin sensitivity, cardiorespiratory fitness, physical activity, depression symptoms, and body measurements.

CONCLUSION

Study findings will guide the ideal sequencing of two brief T2D prevention interventions for ameliorating the course of insulin resistance and lessening T2D risk in vulnerable adolescents. These interventions will likely be cost-effective and scalable for dissemination, having the potential for significant public health impact on communities at risk for T2D.

Adolescence is characterized by more sedentary behavior and less physical activity even among highly active forager-farmers

Over 80% of adolescents worldwide are insufficiently active, posing massive public health and economic challenges. Declining physical activity (PA) and sex differences in PA consistently accompany transitions from childhood to adulthood in post-industrialized populations and are attributed to psychosocial and environmental factors. An overarching evolutionary theoretical framework and data from pre-industrialized populations are lacking. In this cross-sectional study we test a hypothesis from life history theory, that adolescent PA reductions reflect an evolved strategy to conserve energy, given the increasing sex-specific energetic demands for growth and reproductive maturation. Detailed measures of PA and pubertal maturation are assessed among Tsimane forager-farmers (age: 7-22 yrs.; 50% female, n=110). We find that 71% of Tsimane sampled meet World Health Organization PA guidelines (≥60 minutes/day of moderate-to-vigorous PA). Consistent with post-industrialized populations, we observe sex differences and inverse age-activity associations mediated by Tanner stage. Physical inactivity in adolescence is distinct from other health risk behaviors and also not merely resulting from obesogenic environments.

Correlates of the Physical Activity Decline during Childhood

PURPOSE

This study aimed to describe longitudinal trends in children's moderate-to-vigorous physical activity (MVPA) and to investigate associations with individual, familial, and school characteristics.

METHODS

A sample of 341 Portuguese children age 5-10 yr (173 girls) from six age cohorts was followed over 3 yr using a mixed-longitudinal design. Physical activity, body mass index (BMI), gross motor coordination, and musculoskeletal fitness were assessed annually. Information on socioeconomic status and school characteristics was collected and analyzed with mixed models.

RESULTS

MVPA shows a similar declining trend in both sexes, but on average, boys exceeded the World Health Organization recommendations of 60 min·d -1 . The best model showed that boys spend, on average, more time in MVPA than girls. Children with lower BMI are less prone to the decline in MVPA, whereas higher levels of musculoskeletal fitness were associated with lower declines in MVPA. Of all school characteristics, only playground dimension was related to MVPA decreasing trajectories.

CONCLUSIONS

MVPA systematically declines from 5 to 10 yr of age in both boys and girls, but boys remained more active than girls across the age range. The best predictors of MVPA decline are sex, BMI, musculoskeletal fitness, and school playground dimension.

A profile of children's physical activity data from the 2012 and 2015 health survey for England

Background

Low childhood physical activity levels constitute an important modifiable risk for adult non-communicable disease incidence and subsequent socio-economic burden, but few publications have explored age and sex related patterns within the UK population. The aims were to profile child physical activity data from the Health Survey for England from 2012 (1,732 respondents) and 2015 (5,346 respondents).

Methods

Reported physical activity episodes were converted to metabolic equivalents with reference to child-specific compendiums. Physical activity levels were aggregated for each domain, and again to produce total physical activity estimates. Contributions from each domain to total physical activity were explored, stratifying for age, sex, socio-economic deprivation, ethnicity, and weight status. Further analyses were run stratifying for physical activity levels. Few differences were detected between the survey iterations.

Results

Boys reported higher absolute levels of physical activity at all ages and across all domains. For boys and girls, informal activity reduces with age. For boys this reduction is largely mitigated by increased formal sport, but this is not the case for girls. Absolute levels of school activity and active travel remained consistent regardless of total physical activity, thereby comprising an increasingly important proportion of total physical activity for less active children.

Conclusions

We recommend a specific focus on establishing and maintaining girl’s participation in formal sport thorough their teenage years, and a recognition and consolidation of the important role played by active travel and school-based physical activity for the least active children.

Trajectories of physical activity and sedentary time in Norwegian children aged 3-9 years: a 5-year longitudinal study

BACKGROUND

Limited evidence exists regarding the longitudinal development of physical activity during early to mid childhood. The aim of this study was to determine physical activity and sedentary time trajectories in children aged 3‒9 years from Western Norway.

METHODS

A sample of 294 children (51% boys; aged 3‒5 years at baseline) from the Sogn og Fjordane Preschool Physical Activity Study was followed annually over 5 years (2015‒2019). Physical activity was measured every autumn during this period using hip-based accelerometry (ActiGraph GT3X+). Data was processed as counts. We used linear mixed models to analyse the data. Primary analyses included trajectories for total and intensity-specific physical activity (light, moderate, vigorous, and moderate to vigorous intensity) and sedentary time for boys and girls using 1-s epoch. Secondary analyses included trajectories for weekdays versus weekend days, preschool/school hours versus after school hours, and 1- versus 60-s epoch lengths.

RESULTS

Over the total day, significant associations with age were found for boys and girls for all physical activity intensities and sedentary time (p < .001). Total physical activity peaked at age 5, whereas intensity-specific physical activity levels peaked at age 3 to 8 years (light intensity: 3-4 years; moderate intensity: 4-7 years; vigorous intensity: 7-8 years; moderate to vigorous intensity: 5-8 years). Boys had higher physical activity levels and more favourable trajectories than girls. Sedentary time increased from ages 3 to 9. Changes over time were larger for weekdays than for weekend days and larger for preschool/school hours than for after school hours. The use of a 60-s epoch resulted in larger changes over time than a 1-s epoch.

CONCLUSIONS

Our findings suggest physical activity levels peaked between the ages of 3 and 8 years. Finding ways to prevent decline in physical activity during the transition from preschool to primary school is important, especially for girls. Standardising epoch length will help when comparing physical activity and sedentary behaviour across studies.

Associations between socioeconomic position and young people's physical activity and sedentary behaviour in the UK: a scoping review

OBJECTIVE

To examine the evidence on the associations between socioeconomic position and young people's physical activity and sedentary behaviours in the UK.

DESIGN

Scoping review.

DATA SOURCES

PubMed, SCOPUS and Web of Science databases were searched for articles published up to and including January 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Observational studies in children and adolescents (aged 5-18 years) from the UK that had assessed associations between at least one indicator of socioeconomic position and at least one outcome of physical activity and/or sedentary behaviour.

DATA EXTRACTION AND SYNTHESIS

Data were extracted by one reviewer and 20% were double checked. Indicators of socioeconomic position were tabulated with domains of physical activity and sedentary behaviour.

RESULTS

Fifty-seven publications were included in the review; 37 publications from 19 studies (k=23) of children and 21 publications from 15 studies (k=23) of adolescents. Most studies were cross-sectional. 63% of studies of children, and 40% of studies of adolescents assessed Index of Multiple Deprivation. Eighteen studies measured physical activity in children, 13 measured sedentary behaviour. Eleven studies of adolescents included a measure of physical activity, 10 included a measure of sedentary behaviour. Among children and adolescents, the association between socioeconomic position and measures of either physical activity or sedentary behaviour was highly variable depending on the measure of both socioeconomic position used and the behavioural outcome, with the exception of higher family affluence which was consistently associated with higher reported physical activity among adolescents.

CONCLUSION

Physical activity and sedentary behaviours of children and adolescents in the UK are complex and influenced by multiple indicators of socioeconomic position that are, in most cases, different across age stages, outcomes examined and measurement tools. Greater consistency in the use and measures of socioeconomic position as well as outcomes of behaviour are required for robust country-specific meta-analyses.

Physical activity and sedentary behaviour of female adolescents in Indonesia: A multi-method study on duration, pattern and context

Background/Objective

Exploring comprehensive information on the duration, pattern and context of physical activity and sedentary behaviour is important to develop effective policies and interventions. Especially in lower- and middle-income countries, our understanding of these health-behaviours is limited. Our study aimed to investigate physical activity and sedentary behaviour of female Indonesian adolescents by using a multi-method approach.

Methods

Female adolescents (n = 5; 13–15 years old) from Yogyakarta, Indonesia wore accelerometers and automated wearable cameras for four days, and completed diaries, and interviews between February and March 2020.

Results

Participants’ activity, especially on non-school days, was dominated by light-intensity physical activity. Four of the 5 participants did not meet the physical activity guidelines. Participants spent a great proportion of time on screen-based sedentary behaviour (school days: 83.2% of wear time; non-school days: 75.7% of wear time). During school days, most physical activity and sedentary behaviour was done at school. Screen time was mainly done on the school day evenings and weekend mornings. Participants mostly used smartphones in the bedroom and living room in a solitary environment. Interviews suggest that the high amount of screen time seemed to be influenced by a lack of awareness of current guidelines, the feeling of urgency to check information, and the lack of parental supervision. Non-screen-based sedentary behaviour comprised just over 10% of total camera images.

Conclusion

The use of a multi-method approach facilitated a rich understanding of the duration, patterns, and contexts of physical activity and sedentary behaviour in participants. Future studies might consider using similar methods in a larger sample.

Breakfast Consumption Suppresses Appetite but Does Not Increase Daily Energy Intake or Physical Activity Energy Expenditure When Compared with Breakfast Omission in Adolescent Girls Who Habitually Skip Breakfast: A 7-Day Randomised Crossover Trial

With concerns that adolescent girls often skip breakfast, this study compared the effects of breakfast consumption versus breakfast omission on free-living physical activity (PA) energy expenditure (PAEE) and dietary intakes among adolescent girls classified as habitual breakfast skippers. The participants went through two 7-day conditions in a trial with a crossover design: daily standardised breakfast consumption (energy content: 25% of resting metabolic rate) before 09:00 (BC) and daily breakfast omission (no energy-providing nutrients consumed) until 10:30 (BO). Free-living PAEE, dietary intakes, and perceived appetite, tiredness, and energy levels were assessed. Analyses were linear mixed models. Breakfast manipulation did not affect PAEE or PA duration. Daily fibre intake was higher (p = 0.005; d = 1.31), daily protein intake tended to be higher (p = 0.092; d = 0.54), post-10:30 carbohydrate intake tended to be lower (p = 0.096; d = 0.41), and pre-10:30 hunger and fullness were lower and higher, respectively (p ≤ 0.065; d = 0.33-1.01), in BC versus BO. No other between-condition differences were found. Breakfast-skipping adolescent girls do not compensate for an imbalance in energy intake caused by breakfast consumption versus omission through subsequent changes in PAEE but may increase their carbohydrate intakes later in the day to partially compensate for breakfast omission. Furthermore, breakfast can make substantial contributions to daily fibre intake among adolescent girls.

Examining if changes in gender-specific and co-ed intramural programs affect youth physical activity over time: a natural experiment evaluation using school- and student-level data from the COMPASS study

BACKGROUND

Despite the benefits of physical activity (PA), the majority of Canadian youth are falling short of the recommended 60 min of moderate-to-vigorous physical activity (MVPA) per day. School-based physical activity programs such as intramurals, are important opportunities for youth to be physically active. There is limited evidence available on the impact of gender-specific (e.g., female-only, male-only) and co-ed intramurals on youth PA over time, however, evidence suggests female-only intramurals may be important for female MVPA. This research aims to capitalize on a natural experiment to generate practice-based evidence on the impact of changes in gender-specific and co-ed intramurals on youth MVPA over time.

METHODS

This study used linked longitudinal school- and student-level data from Ontario secondary schools in year 5 (Y5:2016-2017), year 6 (Y6: 2017-2018) and year 7 (Y7: 2018-2019) of the COMPASS study. Data on intramurals from 55 schools were used to determine the changes to gender-specific and co-ed intramurals that occurred from Y5 to Y6. Baseline demographic characteristics were measured and data on PA and sport participation were collected in Y5, Y6 and Y7 on a sample of 4417 students. Hierarchical linear mixed regression models were used to estimate how changes in gender-specific and co-ed intramurals were associated with youth MVPA over time.

RESULTS

Participation in intramural, varsity and community sport were all positively and significantly associated with youth MVPA. Changes in gender-specific and co-ed intramurals were not significantly associated with youth MVPA in Y6 or Y7. However, the positive association between maintaining the addition of gender-specific intramurals on female MVPA in Y7 was on par with the significance level of α = 0.05, suggesting that adding gender-specific intramurals may be important for female MVPA.

CONCLUSIONS

Adding gender-specific and co-ed intramurals may not be sufficient strategies to increase PA among youth. Further research should explore the effect of gender-specific intramurals on youth PA, as this study may have been underpowered at the school-level. Gender-specific intramurals may promote a supportive PA environment that promotes MVPA, especially among females. These intramurals may be an important component of more comprehensive strategies to increase youth MVPA.

Multi-Component Physical Activity Interventions in the UK Must Consider Determinants of Activity to Increase Effectiveness

Interventions to increase physical activity in children have adopted broad approaches and achieved varying success. There is a need to adopt approaches underpinned with a theoretical basis. Accordingly, the aim here was to implement and evaluate a 12-week intervention designed using the concepts of the COM-B model to determine the effect this has on physical activity levels. One hundred and forty-seven school-age children (mean age 8.9 ± 1.3 years) took part in a 12-week program delivered in a school setting. Topics included physical activity, healthy eating, sleep quality and reducing screen time/sedentary activities when not in school. A sample of participants wore a wrist-worn accelerometer for seven days pre-and post-intervention (N = 11). The physical activity frequency was unchanged (2.9 ± 1.0 AU) when compared with post-intervention values (3.1 ± 0.8 AU, mean increase 6.8 ± 3.7%, p > 0.05). Changes were observed in the daily consumption of fruit and vegetables (pre-intervention 44.6% vs. post-intervention 60.2%, p < 0.05). Sedentary time, light activity, moderate activity and vigorous activity were unchanged post-intervention (p > 0.05). There is a need to adopt a broader approach that incorporates a theoretical basis and considers the complex ways by which physical activity behaviours are influenced.

Connect through PLAY: a randomized-controlled trial in afterschool programs to increase adolescents' physical activity

The current study is a randomized controlled trial to test a novel 10-week climate-based intervention within pre-existing afterschool programs, designed to increase moderate-to-vigorous physical activity (MVPA) in underserved (low-income, minority status) middle school youth by addressing youth social developmental needs. Participants (n = 167; 56% female; 62% Black; 50% overweight/obese) enrolled in 6 middle schools were randomized to either the Connect through PLAY intervention or a wait-list control. Process evaluation measures (i.e., observations of external evaluators; staff surveys) indicated that essential elements were implemented with fidelity, and staff endorsed implementation ease/feasibility and acceptability. Regression analysis demonstrated that participation in the intervention (vs. control) was associated with an increase of 8.17 min of daily accelerometry-measured MVPA (56 min of additional weekly MVPA) at post-intervention controlling for baseline MVPA, school, gender, and weight status. The results provide support for social-motivational climate-based interventions for increasing MVPA in underserved youth that can inform future school-based health initiatives.Trial Registration: NCT03850821: https://clinicaltrials.gov/ct2/show/study/NCT03850821?term=NCT03850821&rank=1.

A quasi-experimental examination of how changes in school-level intramurals are associated with physical activity among a sample of Canadian secondary school students from the COMPASS study

Introduction

Intramurals in schools may encourage physical activity among youth. Schools are continuously making changes to these intramurals, yet it is not well understood how these changes impact youth physical activity. The main objective of this research was to examine if changes in the number of intramurals were associated with youth physical activity over time with a secondary objective to explore the association between sport participation and physical activity among youth over time.

Methods

This study used three years of linked longitudinal school- and student-level data from Ontario schools in year 5 (Y5: 2016–2017), year 6 (Y6: 2017–2018) and year 7 (Y7: 2018–2019) of the COMPASS study. Data on intramurals from 55 schools were collected from the School Programs and Policies questionnaire to determine intramural changes that were made from Y5 to Y6. Using the COMPASS Student Questionnaire, baseline demographics were collected and data on physical activity and sport participation were measured at Y5, Y6 and Y7 on 4417 students. Hierarchical linear mixed regression models were used to estimate how changes in intramurals were associated with youth physical activity over time.

Results

Changes in school-specific intramurals were not significantly associated with physical activity over time. Intramural, varsity and community sport participation were all positively and significantly associated with youth physical activity among female and males.

Conclusions

Intramural, varsity and community sport participation are important opportunities for youth physical activity. Schools should offer a variety of intramural and varsity sports to encourage physical activity. Although adding intramurals may not be effective at increasing youth physical activity, they may be effective when used in combination with other strategies to increase physical activity.

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The use of an indicator variable in multi-level modeling is a novel method to evaluate a natural experiment.

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Intramural, varsity and community sport participation were positively associated with youth physical activity.

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Intramural changes were not associated with youth physical activity over time.

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Intramurals may be a useful part of a more comprehensive approach to increasing youth physical activity.

Methodological Considerations for Studies in Sport and Exercise Science with Women as Participants: A Working Guide for Standards of Practice for Research on Women

Until recently, there has been less demand for and interest in female-specific sport and exercise science data. As a result, the vast majority of high-quality sport and exercise science data have been derived from studies with men as participants, which reduces the application of these data due to the known physiological differences between the sexes, specifically with regard to reproductive endocrinology. Furthermore, a shortage of specialist knowledge on female physiology in the sport science community, coupled with a reluctance to effectively adapt experimental designs to incorporate female-specific considerations, such as the menstrual cycle, hormonal contraceptive use, pregnancy and the menopause, has slowed the pursuit of knowledge in this field of research. In addition, a lack of agreement on the terminology and methodological approaches (i.e., gold-standard techniques) used within this research area has further hindered the ability of researchers to adequately develop evidenced-based guidelines for female exercisers. The purpose of this paper was to highlight the specific considerations needed when employing women (i.e., from athletes to non-athletes) as participants in sport and exercise science-based research. These considerations relate to participant selection criteria and adaptations for experimental design and address the diversity and complexities associated with female reproductive endocrinology across the lifespan. This statement intends to promote an increase in the inclusion of women as participants in studies related to sport and exercise science and an enhanced execution of these studies resulting in more high-quality female-specific data.

Examining If Changes in the Type of School-Based Intramural Programs Affect Youth Physical Activity over Time: A Natural Experiment Evaluation

(1) School-based physical activity programs such as intramurals provide youth with inclusive opportunities to be physically active, yet we know little about how types of intramurals (e.g., team and individual sports) may contribute to youth MVPA. This research aims to evaluate how real-world changes in types of intramurals available in schools impact youth physical activity over time. (2) This study used three years of longitudinal school- and student-level data from Ontario schools participating in year 5 (2016–2017), year 6 (2017–2018) and year 7 (2018–2019) of the COMPASS study. Data on types of intramural programs from 55 schools were obtained, baseline demographic characteristics were measured and data on physical activity and sport participation were collected on a sample of 4417 students. Hierarchical linear mixed regression models were used to estimate how changes in the type of intramurals associate with youth MVPA over time. (3) Regardless of participation, adding individual and team intramurals was significantly and positively associated with female MVPA in Y6. (4) The indirect, but positive relationship between adding individual and team intramurals and female MVPA may be explained by other characteristics of the school environment that are conducive to female MVPA.

“I feel proper self-conscious all the time”: A qualitative study of adolescent girls’ views of menstruation and physical activity

Background: Many children and adolescents do not engage in sufficient physical activity. Girls are less active than boys, and their activity levels decline more steeply with age. Menstruation may be associated with the decline in girls’ activity but there are few person-centred studies examining adolescent girl’s experiences of menstruation and physical activity. These are needed to understand the influence that menstruation has on the physical activity experiences of girls to inform effective interventions. Methods: Focus groups were conducted with 46 girls aged 13-15 years across three schools. The discussions explored; experiences of, barriers to and facilitators of being active during menstruation; experiences in physical education/sports teams; and talking with others about periods and being active. Data were analysed using thematic analysis. Results: Four themes were identified: 1) balancing perceived barriers and benefits 2) motivation and enjoyment, 3) social influences and 4) coping strategies. Participants reported using diverse strategies to overcome barriers to being active posed by menstruation and the importance of peer-support and enjoyable forms of activity. Conclusions: Menstruation has a strong influence on girls’ physical activity experiences through intra- and inter-personal factors. The implications for how these can be addressed in efforts to increase girls’ physical activity are discussed.

The relationship between sleep habits, lifestyle factors, and achieving guideline-recommended physical activity levels in ten-to-fourteen-year-old Japanese children: A cross-sectional study

The current focus of meeting the physical activity guidelines for children and young people include preventing conditions such as high blood cholesterol, high blood pressure, metabolic syndrome, obesity, low bone density, depression, and injuries. However, the relationship between sleep habits and meeting physical activity guidelines is still unclear. This study aimed to assess this relationship among fifth- to eighth-grade (ages 10-14) Japanese children. This cross-sectional study included 3,123 children (boys: 1,558, girls: 1,565, mean age: 12.5 ± 1.2 years). Questionnaires were used to assess parameters such as moderate-to-vigorous physical activity per day, school and weekend night sleep durations, social jetlag, daytime sleepiness, napping, screen time, and breakfast intake. Participants were divided into an achievement and a non-achievement group depending on their physical activity guideline achievement status (i.e., whether they met the children's physical activity guideline of 60 min or more of moderate-to-vigorous physical activity per day). Then, to determine the sleep habits in relation to the children's achievement of guideline-recommended physical activity levels, multivariate logistic regression analyses were conducted. In fifth- and sixth-grade (ages 10-12) boys, an inverse association was observed between physical activity guideline achievement and daytime sleepiness. In seventh- and eighth-grade (ages 12-14) boys, physical activity guideline achievement was inversely associated with social jetlag and skipping breakfast. Additionally, in seventh- and eighth-grade girls, physical activity guideline achievement was inversely associated with inappropriate sleep duration on weekends and screen time. These results suggest that meeting the physical activity guideline is related to favorable sleep habits in Japanese children. However, their relevance may differ by school type and gender.

Physical activity and health in Chinese children and adolescents: expert consensus statement (2020)

China is experiencing significant public health challenges related to social and demographic transitions and lifestyle transformations following unprecedented economic reforms four decades ago. Of particular public health concern is the fourfold increase in overweight and obesity rates in the nation's youth population, coupled with the low prevalence of adolescents meeting recommended levels of physical activity. Improving the overall health of China's more than 170 million children and adolescents has become a national priority. However, advancing nationwide health initiatives and physical activity promotion in this population has been hampered by the lack of a population-specific and culturally relevant consensus on recommendations for achieving these ends. To address this deficiency and inform policies to achieve Healthy China 2030 goals, a panel of Chinese experts, complemented by international professionals, developed this consensus statement. The consensus was achieved through an iterative process that began with a literature search from electronic databases; in-depth reviews, conducted by a steering committee, of the resulting articles; and panel group evaluations and discussions in the form of email correspondence, conference calls and written communications. Ultimately, the panel agreed on 10 major themes with strong scientific evidence that, in children and adolescents aged 6-17, participating in moderate to vigorous physical activities led to multiple positive health outcomes. Our consensus statement also (1) highlights major challenges in promoting physical activity, (2) identifies future research that addresses current knowledge gaps, and (3) provides recommendations for teachers, education experts, parents and policymakers for promoting physical activity among Chinese school-aged children and adolescents. This consensus statement aligns with international efforts to develop global physical activity guidelines to promote physical activity and health and prevent lifestyle-related diseases in children and adolescents. More importantly, it provides a foundation for developing culturally appropriate and effective physical activity interventions, health promotion strategies and policy initiatives to improve the health of Chinese children and adolescents.

Exploring the relationship between adolescent biological maturation, physical activity, and sedentary behaviour: a systematic review and narrative synthesis

CONTEXT

Across adolescence, there is a notable decline in physical activity in boys and girls. Maturational timing may be a risk factor for disengagement from physical activity and increased sedentary behaviours during adolescence.

OBJECTIVE

This systematic review aimed to summarise literature that examined the relationship between maturational timing, physical activity and sedentary behaviour in adolescents.

METHODS

Six electronic databases were searched for articles that assessed biological maturation and physical activity (including sports participation and active transportation) or sedentary behaviours in adolescents. Two reviewers conducted title, abstract, and full-text screening, reference and forward citation searches. Included articles were evaluated for quality using a standardised tool. A narrative synthesis was used to analyse the findings due to the heterogeneity of the studies.

RESULTS

Searches yielded 78 articles (64 unique studies) that met the inclusion criteria, representing 242,316 participants (153,179 unique). Studies ranged from 30.0% (low) to 91.7% (high) in quality. An inverse relationship between maturational timing and physical activity (in 50 and 60% of studies in boys and girls, respectively) and a positive relationship between maturational timing and sedentary behaviour (in 100% and 53% of studies in boys and girls, respectively) was most commonly reported. Evidence supporting an association between maturational timing, sports participation, and active transportation was inconsistent.

CONCLUSIONS

While this review demonstrates some evidence for early maturational timing as a risk factor for disengagement from physical activity and increase in sedentary behaviours, the reviewed literature also demonstrates that this relationship is complex. Future research that tracks maturity-related variations in physical activity and sedentary behaviours over adolescence is warranted.

Promoting Health-Related Cardiorespiratory Fitness in Physical Education: The Role of Class Intensity and Habitual Physical Activity

Physical education (PE) has the potential to promote health-related fitness, however, its contribution is still not clear. The aim of this study was to assess whether students’ health-related cardiorespiratory fitness (CRF) improved from the beginning to the end of the school year, and to examine the role of PE class intensity and habitual physical activity (PA) in promoting students’ CRF. This observational study employed a longitudinal design. Participants were 212 7th and 8th grade students (105 boys), mean age 12.9 years old, followed during one school year, from September 2017 to June 2018. The Progressive Aerobic Cardiovascular Endurance Run (PACER) was used to assess CRF at baseline and follow-up. PA was measured using accelerometers. PE class intensity was assessed using the System for Observing Fitness Instruction Time. Findings indicated that from the beginning to the end of the school year, a greater percentage of participants were in the CRF healthy fitness zone (73.1% to 79.7%, p = 0.022). Among boys, participating in organized sports (B = 4.61, 95% confidence interval [CI]: 0.33, 8.88) and the percentage of PE time being very active (B = 0.90, 95% CI: 0.44, 1.35) were positively associated with the change in PACER laps. Among girls, daily vigorous PA (B = 0.38, 95% CI: 0.15, 0.60) and participating in organized sports (B = 4.10, 95% CI: 0.93, 7.27) were also positively associated with PACER change, while being overweight or obese (B = −5.11, 95% CI: −8.28, −1.93) was negatively associated. In conclusion, PE was demonstrated to have a positive role in the promotion of CRF, especially among boys, while for girls, habitual PA seems to have a greater contribution. Nevertheless, results and conclusions should be considered carefully, taking into account study limitations, such as the non-direct measures of PE class intensity, CRF, and school setting.

Physical Activity, Sport and Physical Education in Northern Ireland School Children: A Cross-Sectional Study

Internationally, insufficient physical activity (PA) is a major health concern. Children in Northern Ireland (NI) are recorded as having the lowest levels of PA in the United Kingdom (UK). To date, validated and representative data on the PA levels of NI school children are limited. The aim of this study was to provide surveillance data on self-reported PA, sport and physical education (PE) participation of school children in NI. Differences between genders and factors associated with PA were also examined. A representative sample of primary (n = 446) and post-primary (n = 1508) children was surveyed in school using validated self-report measures. Findings suggest that PA levels are low, with a minority of children (13%) meeting the PA guidelines (primary pupils 20%, post-primary pupils 11%). NI school children have lower levels of PA, PE and sports participation than UK and European peers. A trend of age-related decline across all the domains of PA was apparent. The data presented highlighted that females are less likely to achieve PA guidelines, children from lower socio-economic background participate in school and community sport less often, and that enjoyment and social support are important variables in PA adherence. Policy solutions that would support implementation e.g., mandatory minimum PE time, whole school approaches to PA promotion and targeted investment in schools, particularly in areas of deprivation and for females, are suggested.

A study protocol for a clustered randomised controlled trial to evaluate the effectiveness of a peer-led school-based walking intervention on adolescent girls' physical activity: the Walking In ScHools (WISH) study

Background

Adolescent girls in the UK and Ireland are failing to meet current physical activity guidelines. Physical activity behaviours track from childhood to adulthood and it is important that adolescent girls are provided with opportunities to be physically active. Walking has been a central focus for physical activity promotion in adults and may effectively increase physical activity levels among younger people. Following on from a pilot feasibility trial, the purpose of this cluster randomised controlled trial (c-RCT) is to evaluate the effectiveness of a novel, low-cost, peer-led school-based walking intervention delivered across the school year at increasing physical activity levels of adolescent girls.

Methods

The Walking In ScHools (WISH) Study is a school-based c-RCT conducted with girls aged 12–14 years from eighteen schools across the Border Region of Ireland / Northern Ireland. Following baseline data collection, schools will be randomly allocated to intervention or control group. In intervention schools, female pupils aged 15–18 years will be invited to train as walk leaders and will lead younger pupils in 10–15 min walks before school, at break and lunch recess. All walks will take place in school grounds and pupils will be encouraged to participate in as many walks as possible each week. The intervention will be delivered for the whole school year (minimum 20–22 weeks). The primary outcome measure is accelerometer-measured total physical activity (counts per minute) (end of intervention). Secondary outcomes will include time spent in sedentary behaviour, light, moderate and vigorous intensity physical activity, anthropometry measures, social media usage and sleep. A mixed-methods process evaluation will also be undertaken.

Discussion

The WISH Study will examine the effectiveness of a low-cost, school-based, peer-led walking intervention in increasing physical activity in adolescent girls when delivered across the school year. If the intervention increases physical activity, it would benefit adolescent girls in the defined target area with potential for wider adoption by schools across the UK and Ireland.

Trial registration

ISRCTN; ISRCTN12847782; Registered 2nd July 2019.

Decline of physical activity in early adolescence: A 3-year cohort study

This study analyses the changes of moderate-to-vigorous physical activity (MVPA) in a cohort of boys and girls aged 11 (n = 50) and 14 (n = 50). Physical activity was assessed with Bodymedia SenseWear Pro Armband monitor for 6 days in October 2013 and October 2016, considering 90% of daily wear time (21h and 40min). The initial sample (n = 160) included the children who wore the monitors at age 11 but the final analyzed sample included only those children from the initial sample (n = 50), whose data fulfilled the inclusion criteria at age 11 and 14. Physical fitness and somatic characteristics of the final sample (n = 50) were compared to a representative sample of Slovenian schoolchildren at ages 11 (n = 385) and 14 (n = 236) to detect possible bias. Changes in MVPA were controlled for maturity using the timing of adolescent growth spurt as its indicator. The average MVPA decreased more than one quarter (34.96 min) from age 11 to age 14. Children were significantly more active at age 11 than at age 14 (p < 0.01, d = 0.39). The timing of puberty onset in girls was significantly earlier (12.01 ± 1.0 years) (p < 0.01) than in boys (13.2 ± 0.75 years) (p < 0.01, d = 1.35). There was a significant gender difference in moderate-to vigorous physical activity at age 14 (p < 0.05, η2 = 0.12) and between moderate-to vigorous physical activity at age 11 and 14 (η2 = 0.11). After controlling for the timing of adolescent growth spurt the girls at age 11 showed significantly higher level of physical activity than at age 14 (p < 0.01, η2 = 0.17). Early adolescence is crucial for the development of physical activity behaviours, which is especially pronounced in girls. The significant decline of MVPA between ages 11 and 14 in Slovenia are likely influenced by environmental changes since the timing of adolescent growth spurt did not prove as a factor underlying the decline of MVPA.

Longitudinal changes in moderate-to-vigorous-intensity physical activity in children and adolescents: A systematic review and meta-analysis

Moderate-to-vigorous-intensity physical activity (MVPA) is important for childhood obesity prevention and treatment, yet declines with age. Timing and magnitude of the decline in MVPA in children and adolescents are unclear but important for informing effective obesity intervention development. This systematic review aimed to determine and compare the year-to-year changes in MVPA among children and adolescents. Longitudinal studies were identified by searching 10 relevant databases up to December 2018. Studies were eligible for inclusion if they reported accelerometer-assessed MVPA (min day^-1 ) separately for boys and girls and had follow-up duration of at least 1 year. After screening 9,232 studies, 52 were included representing 22,091 aged 3 to 18 year olds (boys=8,857; girls=13,234). Pooled-analysis of the relative change in MVPA per year showed a decline of -3.4% (95% CI, -5.9 to -0.9) in boys and -5.3% (95% CI, -7.6 to -3.1) in girls, across all age groups. There were notable declines in MVPA at age 9 for both boys (-7.8%, 95% CI, -11.2 to -4.4) and girls (-10.2%, 95% CI, -14.2 to -6.3). The relative decline in MVPA affects both sexes from an early age; however, it is greater among girls. Interventions to promote MVPA should start before adolescence.

Physical Activity in Puberty is Associated with Total Body and Femoral Neck Bone Mineral Characteristics in Males at 18 Years of Age

Background and objectives: Studies indicate that genetic and lifestyle factors influence optimal bone development. Adaptations in bone mineral characteristics related to physical activity (PA) are most often observed in pre- and peri-puberty. Longitudinal associations between bone mineral accrual and objectively measured PA in puberty are poorly understood. The present study aims to investigate whether pubertal PA at different intensities is related to bone mineral characteristics in individuals at 18 years of age. Materials and Methods: Anthropometrics, pubertal stage, bone age and PA by accelerometer were measured in 88 boys at the mean age of 12.1 (T1), 13.1 (T2), 14.0 (T3) and 18.0 years (T4). Different bone mineral parameters were measured by dual-energy X-ray at T4. Stepwise multiple regression analysis was performed to determine the effect of bone age, body mass and PA characteristics on measured bone mineral parameters at 18 years of age. Results: Total PA in puberty together with mean pubertal body mass predicted 35.5% of total body (TB) bone mineral density (BMD), 43.0% of TB less head (LH) bone mineral content (BMC) and 48.1% of BMC/height in individuals at 18 years of age. Vigorous PA and body mass in puberty predicted 43.2% of femoral neck (FN) BMD; bone age at T1, vigorous PA and body mass in puberty predicted 47.3% of FN BMC at 18 years of age. No associations between pubertal PA levels and lumbar spine bone mineral characteristics in individuals at 18 years of age were found. Conclusions: Physical activity in puberty has a significant impact on bone mineral characteristics in individuals at 18 years of age, with total PA being a significant predictor of TB BMD and TB LH BMC as well as BMC/height, whereas vigorous PA is a significant predictor of FN BMD and FN BMC.

Self-efficacy, beliefs, and goals: Moderation of declining physical activity during adolescence

OBJECTIVE

To examine whether the decline in physical activity observed from childhood through adolescence is explained by moderating effects of self-efficacy on concurrent changes in children's goals and beliefs about their physical activity environments.

METHOD

Latent growth modeling was used in longitudinal tests in a cohort of 79 boys and 108 girls assessed in 5th, 6th, 7th, 9th, and 11th grades.

RESULTS

Physical activity measured objectively by an accelerometer declined most in students who had bigger declines in self-efficacy and (1) maintained higher perceptions of barriers to physical activity, (2) had bigger declines in enjoyment and fitness goals, or (3) had smaller declines in appearance and social goals.

CONCLUSIONS

Trials of physical activity interventions based on social-cognitive theory should consider that the influence of changing goals on physical activity may differ according to whether students maintain high efficacy beliefs about overcoming barriers to physical activity coincident with perceptions of their physical activity environment. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Cardiorespiratory Fitness in Childhood and Adolescence Affects Future Cardiovascular Risk Factors: A Systematic Review of Longitudinal Studies

BACKGROUND

Although cardiorespiratory fitness (CRF) in childhood and adolescence may be linked to future cardiovascular health, there is currently limited evidence for a longitudinal association.

OBJECTIVES

To provide a systematic review on the prospective association between CRF in childhood and adolescence and cardiovascular disease (CVD) risk factors at least 2 years later.

METHODS

Using a systematic search of Medline, Embase, and SPORTDiscus, relevant articles were identified by the following criteria: generally healthy children and adolescents between 3 and 18 years of age with CRF assessed at baseline, and a follow-up period of ≥ 2 years. The outcome measures were CVD risk factors. We appraised quality of the included articles with STROBE and QUIPS checklists.

RESULTS

After screening 7524 titles and abstracts, we included 38 articles, assessing 44,169 children and adolescents followed up for a median of 6 years. Eleven articles were of high quality. There was considerable heterogeneity in methodology, measurement of CRF, and outcomes, which hampered meta-analysis. In approximately half of the included articles higher CRF in childhood and adolescence was associated with lower body mass index (BMI), waist circumference, body fatness and lower prevalence of metabolic syndrome in later life. No associations between CRF in childhood and adolescence and future waist-to-hip ratio, blood pressure, lipid profile, and glucose homeostasis were observed.

CONCLUSION

Although about half of the included articles reported inverse associations between CRF in childhood and adolescence and future BMI, body fatness, and metabolic syndrome, evidence for other CVD risk factors was unconvincing. Many articles did not account for important confounding factors such as adiposity. Recommendations for future research include standardizing the measurement of CRF, i.e. by reporting VO_2max, using standardized outcome assessments, and performing individual patient data meta-analyses.

Points-Based Reward Systems in Gamification Impact Children's Physical Activity Strategies and Psychological Needs

Gamification is an increasingly popular form of health intervention but its efficacy remains elusive due to a lack of clarity in its conceptualization and operationalization. This study aimed to isolate and determine the direct causal effect of one of the most popular game elements used in gamified interventions, the points-based reward system, on physical activity (PA) in children. A 72-hour field study with children aged 9 to 13 ( N = 67) was conducted using a digital PA intervention featuring a virtual dog, with and without a points-based reward system. PA was assessed with an activity monitor, and overall PA, three levels of PA intensity, and PA strategies during the 3-day intervention were measured. Guided by self-determination theory, the impact of the points-based reward system on children's basic psychological needs was also investigated. Results indicated that the points-based reward system briefly increased PA engagement but did not significantly affect overall PA over time. When given equal number of points regardless of intensity, children approached the PA intervention strategically by engaging in significantly more light intensity and significantly less vigorous intensity PA than children who did not receive points. Results also suggested that the points-based reward system might promote perceptions of relatedness with the virtual agent featured in the gamified intervention.

Pedometer-determined physical activity among primary schoolchildren in Kuala Lumpur

Objective:

The aim of this study was to objectively measure physical activity and its association with sociodemographic factors among Malaysian primary school-age children.

Methods:

A total of 111 primary school children in Kuala Lumpur were selected through random sampling. Activity pattern was determined using pedometers and differences by sex, ethnicity and body mass index categories were analysed. The relationship between pedometer-determined physical activity and sociodemographic factors were also studied.

Results:

Overall, boys attained significantly higher daily step counts than girls (9573 ± 4145 vs 7313 ± 2697). Significant difference in daily step counts between boys and girls were observed during weekdays ( p<0.01), weekends ( p<0.05) and total mean step counts ( p<0.01). Malay ethnicity showed higher daily step counts during weekdays than weekends ( p<0.05). Compared with boys, girls had higher odds (OR=5.58; 95% CI 1.12, 27.77) of not meeting the recommended daily step counts. Those who had low physical activity levels had higher odds (OR=15.75; 95% CI 1.78, 139.33) of not meeting recommended daily step counts than children who had moderate physical activity level.

Conclusion:

Boys were significantly more active than girls and physical activity was greater during weekdays than on weekends. The primary schoolchildren in Kuala Lumpur were sedentary, with minimum physical activity being observed. Differences in sexes and physical activity levels influenced pedometer step counts in children.

Participation in a school-based walking intervention changes the motivation to undertake physical activity in middle-school students

The motivation to perform physical activity is a crucial factor in achieving a persistent active lifestyle. However, motivation decreases with increasing age from childhood to adolescence. The promotion of physical activity in educational settings might be an important tool to increase motivation and, consequently, to decrease sedentary behavior. The aim of this study was to explore the effect of a 4-month school-based walking intervention on motivation to participate in physical activity among Italian middle-school students. This study included 276 students (mean age 13 ± 1 years, 41.3% female). A total of 138 students (intervention group) participated in a brief walking intervention that was added to their routine daily school activity, while a convenience sample of 138 students performed the routine daily school activity. The activity consisted of walking one kilometer outside of school buildings during the morning break. Motivation data were collected before and after the walking breaks using the Participation Motivation Questionnaire (PMQ). Controlling for age, significant interactions between group and time were observed in the "Social Status" [F(1,273) = 4.851; p = 0.028], "Team" [F(1,273) = 6.015; p = 0.015] and "Energy Release" components [F(1,273) = 8.527; p = 0.038]. Specifically, a significant decrease in the "Social Status" components of the PMQ and an increase in the "Team" and "Energy Release" components were observed in the intervention group. On the contrary. control group showed an increase in "Social Status" and a decrease in the "Team" and "Energy Release" components. Within this developmental context, incorporation of the walking activity helped to modify the motivational orientation towards physical activity to include more intrinsic factors, which were related to the possibility of remaining with classmates and peer groups and releasing a surplus of energy.

Time-use and environmental determinants of dropout from organized youth football and tennis

BACKGROUND

Many adolescents drop out of organized sports. Lack of motivation and competing priorities are known as important reasons for dropout. However, time use factors as well as environmental determinants have been largely neglected in the current literature on dropout from youth sports. The aim of this study is to investigate how (changes in) time use and characteristics of the physical environment determine dropout from football and tennis among adolescents.

METHODS

Data on time use and background characteristics were collected through online surveys in 2015 and 2016 among adolescents aged 13-21 (N = 2555), including both the dropped outs and those who still continued membership of their football or tennis clubs. Physical environmental determinants (travel distance to the sports club, and neighbourhood density) were measured objectively. Binary logistic regression analyses were carried out for football and tennis separately to examine the associations between time use (time spent on various activities and changes related to the school and job situation), and environmental factors on the probability of dropping out from sports.

RESULTS

Time spent on sports outside the context of the sports club, and time spent on social or voluntary activities at the sports club was positively associated with continuing being football and tennis members. Tennis players who changed schools or participated in two sports at the same time had a higher probability of dropping out, whereas tennis players who travelled greater distances from home to the tennis club were less likely to drop out.

CONCLUSIONS

Determinants of dropout differed between football and tennis. However, time use variables were important predictors of dropout from football as well as tennis, whereas environmental determinants hardly contributed to the prediction of dropout. To keep youths involved in organized sports, this study recommends that sports professionals should: 1) offer flexibility in training and competition schedules, 2) stimulate participation in social activities and voluntary work at the sports club, 3) pay special attention to their needs and preferences, and 4) encourage possibilities to practice and play sports outside of regular training hours, for instance at the sports club or at playgrounds or parks in the neighbourhood.

Feasibility of implementing an outdoor walking break in Italian middle schools

Brief bouts of physical activity during the school day are an innovative method for increasing physical activity in the school setting. The purpose of the study was to investigate if the introduction of an outdoor active break, based on walking and running, in a middle school in Italy is feasible in terms of implementation (i.e., adherence, costs, safety) and acceptability (i.e., satisfaction, intent to continue use, perceived appropriateness). One hundred and forty students (aged 12 ± 1 years) and 20 teachers (aged 50 ± 8 years) participated in the activity for four months. The activity consisted of walking (or running) one kilometer outside the school buildings during the mid-morning. Data from questionnaires regarding the satisfaction with and the acceptability of the activity were collected.

The activity was safely performed three to four days a week, without any costs to the school or to students’ parents. Students and teachers were satisfied with the activity (positive answers from 95% and 89% of each group, respectively). Moreover, the teachers reported that the program was easy to organize and did not negatively influence their teaching activities. The intervention was easily and safely implemented, and it was considered suitable for the daily routine of an Italian middle school. Further studies are needed to examine its impact on physical activity levels and academic achievement.

Results of a feasibility cluster randomised controlled trial of a peer-led school-based intervention to increase the physical activity of adolescent girls (PLAN-A)

BACKGROUND

Most adolescent girls in the UK do not meet government physical activity recommendations and effective interventions are needed. This study reports the results of a feasibility trial of PLAN-A, a novel school-based peer-led physical activity intervention for adolescent girls.

METHODS

A two-arm cluster randomised controlled feasibility study was conducted in six English secondary schools (4 intervention & 2 control). Year 8 (age 12-13) girls were eligible and randomisation was at school-level. The intervention involved training Year 8 girls (out of school for two consecutive days, plus one top-up day 5 weeks later), who were identified by their peers as influential, to provide informal support to their friends to increase their physical activity. Feasibility of the intervention and the research was examined, including: recruitment, training attendance and data provision rates, evidence of promise of the intervention to affect weekday moderate-to-vigorous physical activity (MVPA), intervention cost and estimation of the sample size for a definitive trial. Accelerometer and questionnaire data were collected at the beginning of Year 8 (Time 0), the end of Year 8 (10-weeks after peer-supporter training) and the beginning of Year 9 (Time 2).

RESULTS

Four hundred twenty-seven girls were recruited (95% recruitment rate). 55 girls consented to be a peer-supporter and 53 peer-supporters were trained (97% of those invited). Accelerometer return rates exceeded 85% at each time point and wear time criteria was met by 83%, 71% and 62% participants at Time 0, 1 and 2 respectively. Questionnaire data were provided by >91% of participants at each time point. Complete-case adjusted linear regression analysis showed evidence of a 6.09 minute (95% CI = 1.43, 10.76) between-arms difference in weekday MVPA at Time 2 in favour of the intervention arm. On average PLAN-A cost £2685 per school to deliver (£37 per Year 8 girl). There were no adverse events. A trial involving 20 schools would be adequately powered to detect a between-arms difference in weekday MVPA of at least six minutes.

CONCLUSIONS

The PLAN-A intervention adopts a novel peer-led approach, is feasible, and shows evidence of promise to positively affect girls' physical activity levels. A definitive trial is warranted.

TRIAL REGISTRATION

ISCTRN, ISRCTN12543546, Registered on 28/7/2015, URL of registry record: http://www.isrctn.com/ISRCTN12543546.

A comparative study found that a seven-year school-based exercise programme increased physical activity levels in both sexes

AIM

This study assessed whether a Swedish school-based exercise intervention programme could increase total physical activity.

METHODS

We followed up 228 children who started school in 1998-2000 seven years later, when they had reached a mean age of 14.8. The 152 children (59% boys) at the intervention school did 200 minutes of physical education per week during that period, and the 76 children (50% boys) in the three control schools did the standard 60 minutes. Questionnaires assessed the durations of total and leisure-time physical activity and screen-time activity at baseline and after five and seven years.

RESULTS

Physical activity and screen-time activity were similar between the two groups before the study started. The intervention group then achieved higher durations of total physical activity than the controls (p < 0.001) and these levels remained in the sex-specific evaluations. There were no differences between the groups in the durations of leisure-time activity (p 0.08-0.77) or screen-time activity (p 0.31-0.91).

CONCLUSION

A school-based exercise intervention programme increased the total duration of physical activity in both sexes without any compensatory increase in screen-time activity. The findings contradict the activity-stat theory, which stated that the duration of physical activity in children is constant.

Insulin resistance is higher in prepubertal girls but switches to become higher in boys at age 16: A Cohort Study (EarlyBird 57)

BACKGROUND

The risk of type 2 diabetes is increasing in teenage girls, and is associated with their greater insulin resistance (IR).

HYPOTHESIS

We hypothesized that the adverse metabolic profile of girls (compared with boys) would persist from childhood through adolescence.

PATIENTS AND METHODS

Community-based longitudinal cohort of 292 children (147 boys) studied annually from 9 to 16 years.

MEASURES

IR (homeostasis-model-assessment-2), high-density lipoprotein-cholesterol (HDL-C), triglycerides, % body-fat (dual-energy x-ray absorptiometry), pubertal stage (age at peak height velocity), physical activity (accelerometry). Multi-level modelling established the age-related trends in IR and lipids and the influence of covariates.

RESULTS

Each year from 9 to 15 years, girls had 21% to 63% higher IR than boys (girls mean IR 0.73-1.33, boys 0.51-0.89, P < .005). At 16 years the gender difference was not significant (girls IR 0.60, boys 0.56, P = .45). Girls had lower HDL-C from 9 to 12 years, higher triglycerides from 9 to 14 years, greater adiposity throughout, and earlier puberty, but boys were more active than girls (all P < .05). After adjustment for %-fat, puberty and activity, the gender difference in IR between girls and boys aged 9 to 15 years became non-significant (IR girls 0.66-1.01, boys 0.65-1.04, P > .07). However, after adjustment at 16 years, girls' IR was 25% lower than boys' (girls 0.44, boys 0.63, P = .001), and they had 22% higher HDL-C (P < .001) and 20% lower triglycerides (P = .003).

CONCLUSIONS

The higher IR of prepubertal and early pubertal girls diminishes during late puberty, and boys begin to exhibit greater metabolic risk. Despite being leaner and more active, boys at 16 years have higher IR than girls, suggesting future higher risk for diabetes, thus we reject our hypothesis.

Physical Activity Duration but Not Energy Expenditure Differs between Daily and Intermittent Breakfast Consumption in Adolescent Girls: A Randomized Crossover Trial

Background

It is not known whether breakfast frequency affects physical activity (PA) in children or adolescents.

Objective

This study examined the effect of daily compared with intermittent breakfast consumption on estimated PA energy expenditure (PAEE) in adolescent girls.

Methods

Under a randomized crossover design, 27 girls [mean ± SD age: 12.4 ± 0.5 y, body mass index (in kg/m2): 19.3 ± 3.0] completed two 7-d conditions. A standardized breakfast (∼1674 kJ) was consumed every day before 0900 in the daily breakfast consumption (DBC) condition. The standardized breakfast was consumed on only 3 d before 0900 in the intermittent breakfast consumption (IBC) condition, alternating with breakfast omission on the remaining 4 d (i.e., only water consumed before 1030). Combined heart rate accelerometry was used to estimate PAEE throughout each condition. Statistical analyses were completed by using condition × time of day repeated-measures ANOVA. The primary outcome was PAEE and the secondary outcome was time spent in PA.

Results

Daily estimated PAEE from sedentary or light-, moderate-, or vigorous-intensity PA and total PAEE were not significantly different between the conditions. The condition × time of day interaction for sedentary time (P = 0.05) indicated that the girls spent an additional 11.5 min/d being sedentary in the IBC condition compared with the DBC condition from 1530 to bedtime (P = 0.04). Light PA was 19.8 min/d longer in the DBC condition than in the IBC condition (P = 0.05), which was accumulated from waking to 1030 (P = 0.04) and from 1530 to bedtime (P = 0.03). There were no significant differences in time spent in moderate PA or vigorous PA between the conditions.

Conclusions

Adolescent girls spent more time in light PA before 1030 and after school and spent less time sedentary after school when a standardized breakfast was consumed daily than when consumed intermittently across 7 d. However, breakfast manipulation did not affect estimated daily PAEE. This trial was registered at www.isrctn.com as ISRCTN74579070.

Behavior Tracking and 3-Year Longitudinal Associations Between Physical Activity, Screen Time, and Fitness Among Young Children

PURPOSE

Understanding the correlates of children's fitness as they develop is needed. The objectives of this study were to 1) examine the longitudinal associations between physical activity (PA), screen time (ST), and fitness; 2) determine if sex moderates associations; and 3) track PA and ST over 3 years.

METHODS

Findings are based on 649 children [baseline = 4.5 (0.5) y; follow-up = 7.8 (0.6) y] from Edmonton, Canada. Parental-reported hour per week of PA and ST were measured at baseline and 3 years later. Fitness (vertical jump, sit and reach, waist circumference, grip strength, predicted VO_2max, push-ups, and partial curl-ups) was measured using established protocols at follow-up. Sex-specific z scores or low/high fitness groups were calculated. Linear or logistic multiple regression models and Spearman correlations were conducted.

RESULTS

Baseline ST was negatively associated with follow-up grip strength [β = -0.010; 95% confidence interval (CI), -0.019 to -0.001]. Associations between baseline PA and follow-up overall fitness (β = 0.009; 95% CI, 0.002 to 0.016) were significant, whereas baseline PA and follow-up VO_2max (β = 0.014; 95% CI, 0.000 to 0.027) approached significance (P < .06). No sex interactions were observed. Moderate and large tracking were observed for PA (r_s = .30) and ST (r_s = .53), respectively.

CONCLUSIONS

PA and ST may be important modifiable correlates of overall fitness in young children.

Effects of a peer-led Walking In ScHools intervention (the WISH study) on physical activity levels of adolescent girls: a cluster randomised pilot study

Background

School-based interventions may be effective at increasing levels of physical activity (PA) among adolescents; however, there is a paucity of evidence on whether walking can be successfully promoted to increase PA in this age group. This pilot study aimed to assess the effects of a 12-week school-based peer-led brisk walking programme on levels of school-time PA post intervention.

Methods

Female participants, aged 11–13 years, were recruited from six post-primary schools in Northern Ireland. Participants were randomized by school (cluster) to participate in regular 10–15-min peer-led brisk walks throughout the school week (the WISH study) (n = 101, two schools) or to continue with their usual PA (n = 98, four schools). The primary outcome measure was school-time PA post intervention (week 12), assessed objectively using an Actigraph accelerometer. Secondary outcome measures included anthropometry, cardiorespiratory fitness and psychosocial measures. Changes in PA data between baseline (T0) and end of intervention (week 12) (T1) were analysed using a mixed between-within subjects analysis of variance with one between (group) and one within (time) subjects factor, with two levels.

Results

Of 199 participants recruited (mean age = 12.4 ± 0.6 years, 27% overweight/obese), 187 had valid accelerometer data for inclusion in subsequent analysis. A significant interaction effect was observed for changes in light intensity PA across the school day (p = 0.003), with those in the intervention increasing their light intensity PA by 8.27 mins/day compared with a decrease of 2.14 mins/day in the control group. No significant interactions were observed for the other PA measures across the intervention. Intervention effects on school-time PA were not sustained four months post intervention.

Conclusions

The intervention increased daily light intensity PA behaviour in these adolescent girls but did not change moderate to vigorous physical activity (MVPA). These findings suggest that a school-based brisk walking intervention may be feasible and can change PA behaviour in the short term, but it is possible that the self-selected walking speeds determined by a peer-leader may not be sufficient to reach MVPA in this age group. Further research is needed to evaluate the potential of school-based brisk walking to contribute to MVPA in adolescent girls.

Trial registration

ClinicalTrials.gov, NCT02871830. Registered on 16 August 2016) 

Tracking of Pedometer-Determined Physical Activity: A 16-Year Follow-Up Study

Background: The aims of this study were to explore the effect of time and long-termed tracking on pedometer-determined physical activity (PA) from early adolescent to the 30s. Methods: PA was measured with pedometers [Yamax™ (SW-200)] during 2000 (time 1), 2003 (time 2), 2005 (time 3), 2010 (time 4), and 2016 (time 5). Anthropometric data were collected during time 1. Data from 59 participants (n = 32 males) were analyzed from early adolescent (time 1) to the 30s (time 5). Results: There was an effect of time for males (P = .005, η2 = .76) and females (P = .002, η2 = .50) where steps per day decreased. Males steps per day tracked between time 1 and time 2 (r = .41, P = .021), time 1 and time 3 (r = .38, P = .03), time 3 and time 4 (r = .42, P = .015), and time 4 and time 5 (r = .50, P = .003). Females steps per day tracked between time 4 and time 5 (r = .39, P = .04). Males took more steps per day than females during time 1 (P = .018), whereas females took more steps per day during time 2 (P = .043) and time 3 (P = .03). Conclusion: There was a significant effect of time, where steps per day decreased between the 5 times of measurement. Steps per day tracked low to moderate in the short time span, yet tracked nonsignificantly from early adolescent to the 30s.

Change in children's physical activity and sedentary time between Year 1 and Year 4 of primary school in the B-PROACT1V cohort

BACKGROUND

The aim of this study was to examine how children's and parents' physical activity changes from Year 1 (5-6) to Year 4 (8-9 years of age).

METHODS

Data are from the Bristol (UK) B-PROACT1V cohort. Fifty-seven primary schools were recruited when the children were in Year 1, with 1299 children and their parents providing data. Forty-seven schools were re-recruited in Year 4, with 1223 children and parents providing data (685 of whom participated in Year 1). Children and at least one parent wore an accelerometer for 5 days including a weekend and mean minutes of sedentary time, moderate-to-vigorous intensity physical activity (MVPA) and accelerometer counts per minute (CPM) were derived. Multiple imputation was used to impute missing data for all 1837 families who took part, including those who participated at just one time. Paired t-tests examined if there was statistical evidence of change in accelerometer measures.

RESULTS

Multiple imputation and observed data were comparable and results using complete observed data were mostly the same as those using imputed data. Imputed data showed that mean boys' CPM decreased from 747 to 673 (difference in mean 74 [95% CI 45 to 103]) and girls' from 686 to 587 (99 [79 to 119]). Boys' time spent in MVPA reduced from 72 to 69 (3 [0 to 6]) and girls' from 62 to 56 (7 [4 to 9]) minutes per day. There were increases in sedentary time for both boys (354 to 428 min, 74 [61 to 88]) and girls (365 to 448, 83 [71 to 96]). There was no evidence of change in parent CPM or MVPA. Mothers' sedentary time increased by 26 min per day [16 to 35].

CONCLUSIONS

There were similar increases in sedentary time in girls and boys between age 5-6 and 8-9, and decreases in MVPA that were more marked in girls. The similarity of multiple-imputed and complete observed data suggest that these findings may not be markedly affected by selection bias. Result support early interventions to prevent the age-related decline in children's physical activity.

Paediatric obesity and cardiovascular risk factors - A life course approach

Childhood obesity is increasingly prevalent worldwide, and Portugal presents one of the highest prevalence of obesity and overweight among the European countries. Since childhood obesity is a risk factor for obesity in adulthood, the high prevalence of overweight and obesity in paediatric age currently experienced is expected to lead to even higher prevalence of obesity in adulthood in future decades. It is well known that the prenatal period and infancy are critical or sensitive periods for obesity development, but a growing body of evidence also suggests a relevant role of childhood and adolescence. The exposure to some factors during these periods or specific time frames within these periods may confer additional risk for obesity development. Paediatric obesity is associated with cardiovascular risk factors both in the short or medium-term, but also in the long term, conferring additional risk for future adult health. However, it is not clear whether the relation between paediatric obesity and adult health is independent of adult adiposity. There is a moderate to high tracking of obesity from paediatric age into adulthood, which may partially explain the association with adult outcomes. Therefore, there has been increasing interest on life course frameworks to study the effect of the dynamics of adiposity across paediatric age on adult outcomes, namely on the cardiovascular disease risk. The use of this approach to study determinants and consequences of obesity raises methodological challenges to summarize the exposure to adiposity/obesity across the life span, being the identification of growth trajectories and the quantification of the duration of obesity among the most used methods. However, further investigation is still needed to explore the best methods to summarize exposure to adiposity and its variation across time.

Physical inactivity and associated factors in Iranian children and adolescents: the Weight Disorders Survey of the CASPIAN-IV study

Introduction: This study aims to assess the associated factors of physical inactivity among Iranian children and adolescents at national level. The second objective is to assess the relationship of physical inactivity with anthropometric measures. Methods: Along with a national surveillance program, this survey on weight disorders was conducted among a nationally-representative sample of Iranian children and adolescents, aged 6-18 years. Students were selected by multi-stage cluster sampling from rural and urban areas of 30 provinces of Iran. The Physical Activity Questionnaire for Adolescents (PAQ-A) was used to assess physical activity (PA). Using PAQ-A instrument, PA of past week categorized as; low PA level, that included those who scored between 1 to 1.9 on the PAQ-A instrument and high PA level that included participants with estimated scores between 2-5 PAQ-A. Results: Participants were 23183 school students (50.8% boys) with a mean age of 12.55 ± 3.3 years, without significant difference in terms of gender. Totally, 23.48% of participants (13.84% of boys and 33.42% of girls) were physically inactive. In multivariate logistic regression model, with increased age in children and adolescence, the odds of a physically inactivity increased (OR: 1.08; 95% CI: 1.07-1.10). The odds of prevalence of both obesity and underweight were high in children and adolescents with low PA. There was a decreasing trend in PA in higher school grades. Conclusion: We found a considerably high prevalence of physical inactivity in Iranian children and adolescents, with higher rates among girls and older ages. However, we did not find correlation between PA and socioeconomic status (SES). Because of the positive relationship between PA and ST, future studies should consider the complex interaction of these two items. Multidisciplinary policies should be considered in increasing PA programs among children and adolescents.

Naturally-occurring changes in social-cognitive factors modify change in physical activity during early adolescence

PURPOSE

To determine whether naturally-occurring changes in children's motives and beliefs are associated with the steep decline in physical activity observed from childhood to early adolescence.

METHODS

Latent growth modeling was applied in longitudinal tests of social-cognitive influences, and their interactions, on physical activity in a large cohort of boys and girls evaluated annually between 5th and 7th grades.

RESULTS

Measurement equivalence of motives and beliefs was confirmed between boys and girls. After adjustment for gender and maturity differences, physical activity declined less in children who reported the least decreases in self-efficacy for overcoming barriers to activity and perceived parental support. Physical activity also declined less in students who persistently felt they had more parental and friend support for activity compared to those who reported the largest decrease in support from friends. After further adjustment for race, the decline in physical activity was less in those who had the largest decrease in perceived barriers and maintained a favorable perception of their neighborhood environment. Changes in enjoyment and social motives were unrelated to change in physical activity.

CONCLUSION

Using an objective measure of physical activity, we confirm that naturally-occurring changes in children's beliefs about barriers to physical activity and their ability to overcome them, as well as perceptions of their neighborhood environment and social support, are concurrent with age-related declines in children's physical activity. The longitudinal findings confirm these putative social-cognitive mediators as plausible, interacting targets of interventions designed to mitigate the marked decline in physical activity that occurs during the transition between elementary and middle schools.

The Role of Urban Environment, Social and Health Determinants in the Tracking of Leisure-Time Physical Activity Throughout Adolescence

PURPOSE

Adolescence may be a period particularly relevant for acquisition of lifelong habits of physical activity (PA). We investigated the tracking of leisure-time PA from 13 to 17 years old and the influence of urban environment and other determinants.

METHODS

As part of the EPITeen cohort (Portugal), we evaluated 969 adolescents living in the city of Porto. Participants were assembled in public and private schools at 13 years and reevaluated at 17 years. Leisure-time PA was evaluated by self-reported questionnaires. The shortest routes from residence to urban green spaces and open sports spaces were calculated using the street network within a Geographical Information System. Odds ratio (OR) and 95% confidence intervals were calculated by multinomial logistic regression.

RESULTS

Among sedentary girls at 13 years, 33.1% were still sedentary at 17 years, 39.8% changed to low, 22.3% to moderate, and only 4.6% changed to vigorous PA. In boys, the respective values were 32.3%, 17.3%, 36.2%, and 14.2%. High PA levels were maintained by 19.5% of the girls and by 41.1% of the boys. After adjustment for parental education and body image at 13 years, practice of sports at 13 years was strongly associated with stable high PA at 17 years: in girls OR = 3.96 (2.21, 7.12); in boys OR = 6.81 (3.30, 14.07). Distance to urban green spaces or to open sports spaces was not associated to changes in leisure-time PA.

CONCLUSION

Practice of sports in early adolescence may be important to promote maintenance of high PA. Urban environment in the vicinity of residence did not affect changes in the practice of leisure-time PA.

Sedentary behaviour across the primary-secondary school transition: A systematic review

The transition from primary/middle school to secondary/high school is likely to be a key period in children's development, characterised by significant changes in their social and physical environment. However, little is known about the changes in sedentary behaviour that accompany this transition. This review aimed to identify, critically appraise and summarise the evidence on changes in sedentary behaviour across the primary - secondary school transition. Published English language studies were located from computerised and manual searches in 2015. Inclusion criteria specified a longitudinal design, baseline assessment when children were in primary/middle school with at least one follow-up during secondary/high school and a measure of sedentary behaviour at both (or all) points of assessment. Based on data from 11 articles (19 independent samples), tracking coefficients were typically in the range of 0.3 to 0.5 and relatively consistent across the different sedentary behaviours examined and durations of follow-up. Both screen-based sedentary behaviour and overall sedentary time increased during the school transition. Overall there was an increase of approximately 10-20min per day per year in accelerometer-assessed sedentary time. Consistent with the broader age-related changes in behaviour observed during this period, sedentary behaviour increases during the transition from primary/middle to secondary/high school. Investigating features of the social and physical environment that might exacerbate or attenuate this trend would be a valuable next step.

Do Interventions to Increase Walking Work? A Systematic Review of Interventions in Children and Adolescents

Background

Physical activity (PA) levels decline as children move into adolescence, with this decline more notable in girls. As a consequence, many young people are failing to meet current PA guidelines. Walking has been a cornerstone of PA promotion in adults and may provide an effective means of increasing PA levels among younger people.

Objective

Our objective was to conduct a systematic review of interventions aimed at promoting increased levels of walking among children and adolescents.

Methods

Eight electronic databases—CINAHL, Cochrane Library CENTRAL database, EMBASE, Medline OVID, PsycINFO, Scopus, SPORTDiscus and Web of Knowledge—were searched from their inception up to January 2015 using predefined text terms: walking terms AND intervention terms AND population terms AND (physical activity OR exercise). Reference lists of published systematic reviews and original articles included in the review were also screened. Included studies were randomised and non-randomised controlled trials reporting a specific measure of walking levels (self-reported or objective) to assess the effectiveness of interventions aimed at promoting walking in children and adolescents (aged 5–18 years). Only full articles published in English in peer-reviewed journals were included. Risk of bias and behaviour change techniques of included studies were assessed.

Results

Twelve studies were included in this review. The majority of studies assessed interventions delivered within an educational setting, with one study conducted within the family setting. Nine of the included studies reported significant increases in walking in intervention groups versus controls. Commonly employed behaviour change techniques within successful interventions included goals and planning, feedback and monitoring, social support and repetition and substitution.

Conclusions

Walking interventions, particularly those conducted in the school environment, have the potential to increase PA in children and adolescents. Conclusions on which interventions most effectively increased walking behaviours in this population were hindered by the limited number of identified interventions and the short duration of interventions evaluated. The short-term effectiveness of the majority of included studies on levels of walking in this population is promising and further research, particularly within non-educational settings and targeted at sub-groups (e.g. adolescent girls and overweight/obese children and adolescents), is warranted.

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-015-0432-6) contains supplementary material, which is available to authorized users.