The bidirectional longitudinal association between academic performance and cardiovascular disease risk factors in adolescents.

INTRODUCTION: The limited prior research examining the association between academic performance and cardiovascular disease (CVD) risk factors in youth did not explore the reciprocal association between these constructs, and analyzed CVD risk factors individually. Thus, the aim of the present study was to explore the bidirectional longitudinal association between clustered CVD risk score and academic performance in adolescents over a 24-month interval. METHODS: A total of 237 adolescents (45.6% girls), aged 13.9 ± 0.3 years old at baseline, from DADOS (Deporte, ADOlescencia y Salud) study were included in this study. A clustered CVD risk score was created by calculating the mean age- and gender-standardized z-scores of waist circumference, systolic blood pressure, total cholesterol to high-density lipoprotein cholesterol ratio, triglycerides, homeostatic model assessment of insulin resistance, and cardiorespiratory fitness (inversed). Academic performance was assessed through the final academic grades and the test of educational abilities. RESULTS: Our results showed that the clustered CVD risk score at baseline was not associated with academic performance 24 months later (all p > .05). Nevertheless, except for physical education, academic grades at baseline were inversely associated with clustered CVD risk score at follow-up in adolescents (ß ranged from -0.140 to -0.102; all p < .05). No associations were found between academic abilities at baseline and clustered CVD risk score at follow-up (all p > .05). CONCLUSION: Academic grades could help predict CVD risk 24 months later during adolescence. Education professionals should foster adolescents' academic performance not only to improve academic results but also to maximize future cardiovascular health benefits.

Child Soccer Players' Perceptions of Strength and Conditioning Training: A Multimethod Approach Using Write, Draw, Show and Tell.

PURPOSE: The use of strength and conditioning training in childhood is a hot topic surrounded by myths and misconceptions. Despite scientific evidence supporting the safety and benefits of this training for children, the lack of representation of their voices poses a challenge in designing training programs that meet their specific needs and requirements. METHODS: Children's views, experiences, and perceptions of strength and conditioning training were explored by Write, Draw, Show and Tell techniques. Sixteen grassroots soccer players aged 11-12 years took part in one of 3 focus groups exploring the topic. Data were analyzed following an inductive approach enabling themes to be explored and later deductive analyses using the Youth Physical Activity Promotion model to create pen profile diagrams. RESULTS: Strength and conditioning were frequently associated with muscle growth, coordination, endurance, and rest. Enabling factors included autonomy, resilience, physical development, and training opportunities. Reinforcing factors included social support, social interference, coaches' communication, role models, and the ways of implementation. CONCLUSIONS: Participants favor integrating strength and conditioning into their soccer training rather than conducting it as a separate session, which is reflected in their enjoyment. Nonetheless, children remain apprehensive about the potential effects of this type of training on their growth.

Reference values for wrist-worn accelerometer physical activity metrics in England children and adolescents.

BACKGROUND: Over the last decade use of raw acceleration metrics to assess physical activity has increased. Metrics such as Euclidean Norm Minus One (ENMO), and Mean Amplitude Deviation (MAD) can be used to generate metrics which describe physical activity volume (average acceleration), intensity distribution (intensity gradient), and intensity of the most active periods (MX metrics) of the day. Presently, relatively little comparative data for these metrics exists in youth. To address this need, this study presents age- and sex-specific reference percentile values in England youth and compares physical activity volume and intensity profiles by age and sex. METHODS: Wrist-worn accelerometer data from 10 studies involving youth aged 5 to 15 y were pooled. Weekday and weekend waking hours were first calculated for youth in school Years (Y) 1&2, Y4&5, Y6&7, and Y8&9 to determine waking hours durations by age-groups and day types. A valid waking hours day was defined as accelerometer wear for ≥ 600 min·d-1 and participants with ≥ 3 valid weekdays and ≥ 1 valid weekend day were included. Mean ENMO- and MAD-generated average acceleration, intensity gradient, and MX metrics were calculated and summarised as weighted week averages. Sex-specific smoothed percentile curves were generated for each metric using Generalized Additive Models for Location Scale and Shape. Linear mixed models examined age and sex differences. RESULTS: The analytical sample included 1250 participants. Physical activity peaked between ages 6.5-10.5 y, depending on metric. For all metrics the highest activity levels occurred in less active participants (3rd-50th percentile) and girls, 0.5 to 1.5 y earlier than more active peers, and boys, respectively. Irrespective of metric, boys were more active than girls (p < .001) and physical activity was lowest in the Y8&9 group, particularly when compared to the Y1&2 group (p < .001). CONCLUSIONS: Percentile reference values for average acceleration, intensity gradient, and MX metrics have utility in describing age- and sex-specific values for physical activity volume and intensity in youth. There is a need to generate nationally-representative wrist-acceleration population-referenced norms for these metrics to further facilitate health-related physical activity research and promotion.

Development of raw acceleration cut-points for wrist and hip accelerometers to assess sedentary behaviour and physical activity in 5-7-year-old children.

This study validated sedentary behaviour (SB), moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) accelerometer cut-points in 5-7-year-old children. Participants (n = 49, 55% girls) wore an ActiGraph GT9X accelerometer, recording data at 100 Hz downloaded in 1 s epochs, on both wrists and the right hip during a standardised protocol and recess. Cut-points were generated using ROC analysis with direct observation as a criterion. Subsequently, cut-points were optimised using Confidence intervals equivalency analysis and then cross-validated in a cross-validation group. SB cut-points were 36 mg (Sensitivity (Sn) = 79.8%, Specificity (Sp) = 56.8%) for non-dominant wrist, 39 mg (Sn = 75.4%, Sp = 70.2%) for dominant wrist and 20 mg (Sn = 78%, Sp = 50.1%) for hip. MVPA cut-points were 189 mg (Sn = 82.6%, Sp = 78%) for non-dominant wrist, 181 mg (Sn = 79.1%, Sp = 76%) for dominant wrist and 95 mg (Sn = 79.3%, Sp = 75.6%) for hip. VPA cut-points were 536 mg (Sn = 75.1%, Sp = 68.7%) for non-dominant wrist, 534 mg (Sn = 67.6%, Sp = 95.6%) for dominant wrist and 325 mg (Sn = 78.2%, Sp = 96.1%) for hip. All placements demonstrated adequate levels of accuracy for SB and PA assessment.

Extrinsic Risk Factors for Primary Noncontact Anterior Cruciate Ligament Injury in Adolescents Aged between 14 and 18 years: A Systematic Review.

BACKGROUND: Adolescents present a high incidence of ACL injury compared with other age groups. Examining the risk factors that predispose adolescents to primary noncontact ACL injury is a key strategy to decrease the number of injuries in this population. OBJECTIVE: The aim of this systematic review was to summarise the existing literature investigating extrinsic risk factors that have been linked with primary noncontact ACL injury risk (identified either using ACL injury occurrence or using screening tests measuring biomechanical mechanisms for noncontact ACL injury) in adolescents including research investigating: (1) the association between extrinsic risk factors and primary noncontact ACL injury risk; and (2) whether primary noncontact ACL injury risk was different in populations or groups exposed to different extrinsic risk factors in adolescents. METHODS: The same search strategy was used in MEDLINE, SPORTDiscus, CINAHL, PubMed and Embase. Articles were included if: written in English; published in peer-reviewed journals; investigating and discussing primary noncontact ACL injury risk associated with extrinsic risk factors; they were original research articles with an observational design; and participants presented a mean age ranging between 14 and 18 years. The Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies (QATOCCS) was used to assess the quality and risk of bias of the articles included in this systematic review. RESULTS: The systematic review included 16 eligible articles published up to August 2022 about extrinsic risk factors for primary noncontact ACL injury including: sport (8 studies); sport exposure amount (5); sport level (3); sport season (1); environment (2); equipment (1). Differences in biomechanical risk factors predisposing to ACL injury were reported by sport in female adolescents playing basketball and soccer; however, no good evidence of differences in primary noncontact ACL injury rate by sport was reported in both male and female adolescents. There was contrasting evidence about associations between sport exposure and biomechanical and neuromuscular risk factors predisposing to ACL injury or primary noncontact ACL injury rate in both male and female adolescent players from different sports. There was weak evidence of differences in biomechanical risk factors predisposing to ACL injury by environmental condition in both male and female adolescents playing soccer and season phase in male adolescents playing basketball. Lastly, few good-quality articles suggested that higher sport level might be associated with increased primary noncontact ACL injury rate in female adolescents playing basketball and floorball and that bracing might not prevent primary noncontact ACL injuries in both male and female adolescent players from different sports. DISCUSSION: The findings emphasise the need for further research to clarify the evidence about extrinsic risk factors and primary noncontact ACL injury in adolescents to develop ACL injury prevention guidelines that would help practitioners and researchers identify adolescents at risk and design future interventions. Future epidemiological studies should collect data about extrinsic factors as well as data about primary noncontact injury separately from secondary injuries or contact injuries to better inform primary noncontact ACL injury prevention in adolescents. REGISTRATION: https://doi.org/10.17605/OSF.IO/VM82F (11/08/2021).

Associations of physical activity dose and movement quality with executive functions in socioeconomically disadvantaged children aged 5-6 years.

BACKGROUND: Growing up in areas of high deprivation can negatively impact children's movement behaviours and cognitive development. Enhancing the quantity and quality of children's movement experiences is believed to enhance cognitive development. This study investigated the association of three different modes of movement assessment, movement proficiency and divergent movement ability (collectively understood as motor competence) and PA dose with executive function in a low socio-economic demographic. Demographics, motor competence, and a combination of motor competence and physical activity were hypothesized to be significantly predictor of executive functions. METHOD: In this cross-sectional study, 360 children aged 5-6 years from deprived areas were assessed using three movement assessments: wrist-worn accelerometery for physical activity dose, Test of Gross Motor Development-3 for movement proficiency, and divergent movement assessment. Executive function, including inhibitory control, working memory, and cognitive flexibility, was measured using the NIH Toolbox on an iPad. Multiple linear regression models were designed to evaluate the independent and combined association of demographics, movement competence and physical activity variables with executive function. RESULTS: The regression analysis, with demographic factors only, explained 12% of EF variance (r2 = 0.12 95%CI 0.06-0.18). In addition to this demographics the model with divergent movement explained 19% of EF variance (r2 = 0.19 95% CI = 0.12-0.28), the model with movement proficiency explained 16% of EF variance (r2 = 0.16 95% CI = 0.08-0.26) and the model with PA dose explained 13% of EF variance (r2 = 0.13 95% CI = 0.07-0.20). In these models both divergent movement and proficiency were significant predictors, whilst physical activity variables were not. The final models, combining motor competence and physical activity variables, explained 24% and 23% of EF variance (r2 = 0.24 CI = 0.14-0.33 and r2 = 0.23 CI = 0.14-0.32). In these models, motor competence variables were significant predictors, and only vigorous physical activity and Euclidean Norm Minus One emerged as significant PA dose predictors. DISCUSSION: These findings emphasise that motor competence and physical activity variables better predict executive functions when they are combined. When considered individually both motor competence variables were significant predictors of executive function whilst physical activity variables were not. Importantly, among the two movement competence facets, divergent movement assessment exhibited the strongest association with executive function. Future interventions should consider how to facilitate both movement and cognitive development in children. Future interventions should consider both the interplay of movement quality and quantity and the importance of environments that invite children's exploratory movement behavior.

Physical activity promoting teaching practices and children's physical activity within physical education lessons underpinned by motor learning theory (SAMPLE-PE).

PURPOSE: Movement competence is a key outcome for primary physical education (PE) curricula. As movement development in children emerges through physical activity (PA), it is important to determine the extent of PA promotion within movement competence focused teaching pedagogies. Therefore, this study aimed to assess children's moderate-to-vigorous PA (MVPA) and related teaching practices in primary PE within Linear pedagogy and Nonlinear pedagogy and to compare this to current practice within PE delivery in primary schools. METHODS: Participants (n = 162, 53% females, 5-6y) were recruited from 9 primary schools within the SAMPLE-PE cluster randomised controlled trial. Schools were randomly-allocated to one of three conditions: Linear pedagogy, Nonlinear pedagogy, or control. Nonlinear and Linear pedagogy intervention schools received a PE curriculum delivered by trained deliverers over 15 weeks, while control schools followed usual practice. Children's MVPA was measured during 3 PE lessons (44 PE lessons in total) using an ActiGraph GT9X accelerometer worn on their non-dominant wrist. Differences between conditions for children's MVPA were analysed using multilevel model analysis. Negative binomial models were used to analyse teaching practices data. RESULTS: No differences were found between Linear pedagogy, Nonlinear pedagogy and the control group for children's MVPA levels during PE. Linear and Nonlinear interventions generally included higher percentages of MVPA promoting teaching practices (e.g., Motor Content) and lower MVPA reducing teaching practices (e.g., Management), compared to the control group. Teaching practices observed in Linear and Nonlinear interventions were in line with the respective pedagogical principles. CONCLUSIONS: Linear and Nonlinear pedagogical approaches in PE do not negatively impact MVPA compared to usual practice. Nevertheless, practitioners may need to refine these pedagogical approaches to improve MVPA alongside movement competence.

The Physical Behaviour Intensity Spectrum and Body Mass Index in School-Aged Youth: A Compositional Analysis of Pooled Individual Participant Data.

We examined the compositional associations between the intensity spectrum derived from incremental acceleration intensity bands and the body mass index (BMI) z-score in youth, and investigated the estimated differences in BMI z-score following time reallocations between intensity bands. School-aged youth from 63 schools wore wrist accelerometers, and data of 1453 participants (57.5% girls) were analysed. Nine acceleration intensity bands (range: 0−50 mg to ≥700 mg) were used to generate time-use compositions. Multivariate regression assessed the associations between intensity band compositions and BMI z-scores. Compositional isotemporal substitution estimated the differences in BMI z-score following time reallocations between intensity bands. The ≥700 mg intensity bandwas strongly and inversely associated with BMI z-score (p < 0.001). The estimated differences in BMI z-score when 5 min were reallocated to and from the ≥700 mg band and reallocated equally among the remaining bands were −0.28 and 0.44, respectively (boys), and −0.39 and 1.06, respectively (girls). The time in the ≥700 mg intensity band was significantly associated with BMI z-score, irrespective of sex. When even modest durations of time in this band were reallocated, the asymmetrical estimated differences in BMI z-score were clinically meaningful. The findings highlight the utility of the full physical activity intensity spectrum over a priori-determined absolute intensity cut-point approaches.

Effect of Linear and Nonlinear Pedagogy Physical Education Interventions on Children's Physical Activity: A Cluster Randomized Controlled Trial (SAMPLE-PE).

BACKGROUND: School-based interventions are a key opportunity to improve children's physical activity (PA); however, there is lack of evidence about how pedagogical approaches to motor learning in physical education (PE) might affect PA in children. Therefore, this study aimed to assess how different pedagogical approaches in PE might affect children's PA. METHODS: Participants (n = 360, 5-6 years) from 12 primary schools within the SAMPLE-PE randomized controlled trial were randomly allocated to either Linear Pedagogy (LP: n = 3) or Nonlinear Pedagogy (NP: n = 3) interventions, where schools received a 15-week PE intervention delivered by trained coaches, or to a control group (n = 6), where schools followed usual practice. ActiGraph GT9X accelerometers were used to assess PA metrics (moderate-to-vigorous PA, mean raw acceleration and lowest acceleration over the most active hour and half hour) over whole and segmented weeks at baseline, immediately post-intervention and 6 months follow-up. Intention to treat analysis employing multilevel modelling was used to assess intervention effects. RESULTS: LP and NP interventions did not significantly affect children's PA levels compared to the control group. CONCLUSION: PE interventions based on LP and NP alone might not be effective in improving habitual PA in children.

Foundational Movement Skills and Play Behaviors during Recess among Preschool Children: A Compositional Analysis.

This study aimed to examine the associations between play behaviors during preschool recess and foundational movement skills (FMS) in typically developing preschool children. One hundred and thirty-three children (55% male; mean age 4.7 ± 0.5 years) from twelve preschools were video-assessed for six locomotor and six object-control FMS using the Champs Motor Skill Protocol. A modified System for Observing Children's Activity and Relationships during Play assessed play behaviors during preschool recess. Associations between the composition of recess play behaviors with FMS were analyzed using compositional data analysis and linear regression. Results: Relative to time spent in other types of play behaviors, time spent in play without equipment was positively associated with total and locomotor skills, while time spent in locomotion activities was negatively associated with total and locomotor skills. No associations were found between activity level and group size play behavior compositions and FMS. The findings suggest that activity type play behaviors during recess are associated with FMS. While active games without equipment appear beneficial, preschool children may need a richer playground environment, including varied fixed and portable equipment, to augment the play-based development of FMS.

Skill Acquisition Methods Fostering Physical Literacy in Early-Physical Education (SAMPLE-PE): Rationale and Study Protocol for a Cluster Randomized Controlled Trial in 5-6-Year-Old Children From Deprived Areas of North West England.

BACKGROUND: There is a need for interdisciplinary research to better understand how pedagogical approaches in primary physical education (PE) can support the linked development of physical, cognitive and affective aspects of physical literacy and physical activity behaviors in young children living in deprived areas. The Skill Acquisition Methods fostering Physical Literacy in Early-Physical Education (SAMPLE-PE) study aims to examine the efficacy of two different pedagogies for PE, underpinned by theories of motor learning, to foster physical literacy. METHODS: SAMPLE-PE will be evaluated through a cluster-randomized controlled trial targeting 5-6 year old children from schools located in areas of high deprivation in Merseyside, North-West England. Schools will be randomly allocated to one of three conditions: Linear Pedagogy, Non-linear Pedagogy, or Control. Non-linear and Linear Pedagogy intervention primary schools will receive a PE curriculum delivered by trained coaches over 15 weeks, while control schools will follow their usual practice. Data will be collected at baseline (T0), immediately post-intervention (T1), and 6 months after the intervention has finished (T2). Children's movement competence is the primary outcome in this trial. Secondary outcomes include physical activity, perceived competence, motivation, executive functions, and self-regulation. An extensive process evaluation will also examine implementation factors such as intervention context, reach, dose, fidelity and acceptability. DISCUSSION: The SAMPLE-PE project will enable better understanding surrounding how to operationalise physical literacy through enrichment of PE practices in early PE. The study will provide robust scientific evidence regarding the efficacy of underpinning PE pedagogy with theories of motor learning to promote the development of physical literacy. TRIAL REGISTRATION: Retrospectively registered on 5th September 2018 at ClinicalTrials.gov, a resource provided by the U.S. National Library of Medicine (Identifier: NCT03551366).

Physiological and technical commitment during a 300-m in-line skating trial in athletes of different age categories.

BACKGROUND: This study investigated the differences in strength, technique and time performance in in-line skaters of three age categories during a 300-meter trial. Possible correlations among these variables were also assessed. METHODS: Thirty-six elite in-line skaters (Cadets, Juniors and Seniors, N.=12 each; 14±1, 16±1, and 24±6 years of age, respectively) performed a 300-m trial on an outdoor oval track. Total time (Ttot), 100-m fractions and duration of each skating technique (initial acceleration phase, straight push and cross-over) were recorded. A squat jump (SJ) was performed before and after the trial. Heart rate, blood lactate concentration ([La-]) and rate of perceived exertion (RPE) were collected before, during and at the end of the trial. RESULTS: Ttot was longer and SJ lower in Cadets compared to the other groups. Seniors employed the cross-over technique for a longer period than the straight push technique, compared to Juniors and Cadets. Ttot correlated negatively with SJ in Seniors. The number of significant correlations between skating techniques' duration and both Ttot and SJ increased with age category. No differences among groups were found for heart rate, [La-] and RPE. CONCLUSIONS: With increasing age category, leg strength appeared to be the more related aspect to skating performance. To improve 300-m in-line skating performance, trainers should pay particular attention to the enhancement of leg strength and cross-over skating technique.

Validity and reliability of submaximal fitness tests based on perceptual variables.

BACKGROUND: Few studies examined the validity of fitness tests based on perception scales. The field-based fitness tests batteries are composed by maximal tests and currently, a battery of submaximal tests does not exist. METHODS: Seventeen physically active male participants (age 40.5±10.7 years) performed the Multistage Fitness Test, the Crunch Test, the Push-Up Test and a Trunk Flexion Test with a submaximal protocol based on perceptual variables that were defined as non-validated submaximal. The mentioned tests were repeated three times to assess their reliability. The participants also performed four validated maximal tests comprising a velocity dependent ramp test on the treadmill, the Crunch Test, the Push-Up Test, and Sit-and-Reach Test. The submaximal tests were correlated to the maximal ones to assess their criterion validity. RESULTS: All the submaximal tests showed an ICC superior to 0.8 apart from the submaximal Crunch Test. The correlation between Maximal Treadmill Test and submaximal Multistage Fitness Test was 0.77. The correlation between Sit-and-Reach Test and submaximal Trunk Flexion Test was 0.71. Correlations equal to 0.66 and 0.60 were found between the maximal and submaximal Crunch Test and Push-Up Test respectively. CONCLUSIONS: The use of submaximal tests based on a fixed value of perception can represent a suitable tool to assess cardiorespiratory fitness and flexibility because of their correlation with the corresponding maximal evaluation tests and because of their reliability. On the contrary, muscular endurance capacity seems not to be assessable in the same manner.

MEDEX 2015: Heart Rate Variability Predicts Development of Acute Mountain Sickness.

Sutherland, Angus, Joseph Freer, Laura Evans, Alberto Dolci, Matteo Crotti, and Jamie Hugo Macdonald. MEDEX 2015: Heart rate variability predicts development of acute mountain sickness. High Alt Med Biol. 18: 199-208, 2017. AIMS: Acute mountain sickness (AMS) develops when the body fails to acclimatize to atmospheric changes at altitude. Preascent prediction of susceptibility to AMS would be a useful tool to prevent subsequent harm. Changes to peripheral oxygen saturation (SpO2) on hypoxic exposure have previously been shown to be of poor predictive value. Heart rate variability (HRV) has shown promise in the early prediction of AMS, but its use pre-expedition has not previously been investigated. We aimed to determine whether pre- and intraexpedition HRV assessment could predict susceptibility to AMS at high altitude with better diagnostic accuracy than SpO2. METHODS: Forty-four healthy volunteers undertook an expedition in the Nepali Himalaya to >5000 m. SpO2 and HRV parameters were recorded at rest in normoxia and in a normobaric hypoxic chamber before the expedition. On the expedition HRV parameters and SpO2 were collected again at 3841 m. A daily Lake Louise Score was obtained to assess AMS symptomology. RESULTS: Low frequency/high frequency (LF/HF) ratio in normoxia (cutpoint ≤2.28 a.u.) and LF following 15 minutes of exposure to normobaric hypoxia had moderate (area under the curve ≥0.8) diagnostic accuracy. LF/HF ratio in normoxia had the highest sensitivity (85%) and specificity (88%) for predicting AMS on subsequent ascent to altitude. In contrast, pre-expedition SpO2 measurements had poor (area under the curve <0.7) diagnostic accuracy and inferior sensitivity and specificity. CONCLUSIONS: Pre-ascent measurement of HRV in normoxia was found to be of better diagnostic accuracy for AMS prediction than all measures of HRV in hypoxia, and better than peripheral oxygen saturation monitoring.