Normative Reference Values for Handgrip Strength in Chilean Children at 8-12 Years Old Using the Empirical Distribution and the Lambda, Mu, and Sigma Statistical Methods.

ABSTRACT: Garcia-Hermoso, A, Cofre-Bolados, C, Andrade-Schnettler, R, Ceballos-Ceballos, R, Fernández-Vergara, O, Vegas-Heredia, ED, Ramírez-Vélez, R, and Izquierdo, M. Normative reference values for handgrip strength in Chilean children at 8-12 years old using the empirical distribution and the lambda, mu, and sigma statistical methods. J Strength Cond Res 35(1): 260-266, 2021-The aim of this study was 2-fold (a) to provide sex- and age-specific handgrip reference standards for Chilean children aged 8-12 years and (b) to compare the levels of handgrip strength of Chilean children with those of children from other countries. This cross-sectional study enrolled 2,026 schoolchildren (boys n = 1,334 and girls n = 692, mean age 10.18 [1.16] years old). Handgrip strength was measured using a hand dynamometer with an adjustable grip. Relative handgrip strength was calculated by dividing handgrip strength by body mass (handgrip strength kg per mass kg). Smoothed centile curves and tables for the 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, and 90th centiles were calculated using Cole's lambda, mu, and sigma method. The results indicate that mean handgrip strength was greater among boys than girls. Handgrip strength peaked at 16.25 (5.03) kg in boys and 14.90 (4.32) kg in girls. In addition, relative handgrip strength peaked at 0.38 (0.08) in boys and 0.34 (0.07) in girls. Chilean children of both sexes scored higher than their South American counterparts from Colombia and Peru but showed lower handgrip strength than European and Australian children. Our results provide, for the first time, sex- and age-specific handgrip reference standards for Chilean children aged 8-12.9 years. These normative reference values could help identify the levels of handgrip strength that need attention to provide appropriate feedback and advice to children about how to best improve their overall physical fitness.

Bullying victimization, physical inactivity and sedentary behavior among children and adolescents: a meta-analysis.

BACKGROUND: Physical activity and sedentary behavior are related with psycho-social variables among youth, however its relationship with bullying victimization is unclear. The aim of the study was to clarify the associations between physical activity and sedentary behaviors with bullying victimization among children and adolescents. METHODS: Two independent authors searched in four databases. The studies were selected/included only if participants were children and/or adolescents and the relationship between physical activity and/or sedentary behavior with bullying victimization was reported. Random-effects meta-analyses were used. RESULTS: A total of 18 cross-sectional studies (including 386,740 children and adolescents, 51.8% females) were reviewed. Our study found that not meeting the physical activity guidelines (Odds Ratio [OR] = 1.14, 95% confidence interval [CI], 1.04 to 1.23) and excessive sedentary behavior (i.e., 2 h per day or more of screen time) (OR = 1.21, 95% CI, 1.14 to 1.28) were associated with 14 and 21% higher bullying victimization, respectively. Consistent associations were also found when we analyzed specific forms of bullying for sedentary behavior, including traditional and cyberbullying. CONCLUSIONS: The present study establishes the first quantitative framework for understanding the influence of physical activity and sedentary behavior on bullying victimization, and lays the groundwork for future studies and interventions aimed to its promotion. TRIAL REGISTRATION: CRD42018099388 .

Healthy Lifestyle Behaviors and Their Association with Self-Regulation in Chilean Children.

BACKGROUND: Self-regulation comprises a series of important competencies, such as the ability to control inner states or responses toward thoughts, attention, emotions, or even performance. The relationship between self-regulation and different healthy lifestyle behaviors among children has not been examined in depth to date. The aim of this study was to explore the association between physical activity, screen time levels, and/or Mediterranean Diet adherence and self-regulation in Chilean children. METHODS: A total of 1561 children aged 8-12 years from eight public schools with low socioeconomic status were included. Physical activity, screen time, Mediterranean Diet, and self-regulation were assessed with validated questionnaires. RESULTS: Children who were classified as active or those who reported less than 2 h per day of screen time had higher self-regulation than those who were classified as inactive or counterparts with 2 h per day or more of screen time, respectively. Using joint categories, active children both with low and high screen time showed higher self-regulation compared to inactive/high screen time peers. Additionally, active groups with adherence or non-adherence to the Mediterranean Diet had higher self-regulation compared to inactive and non-adherence peers. CONCLUSION: Having a greater number of healthy habits, mainly regular physical activity, was associated with higher self-regulation, which might be one potential strategy to promote child social-emotional development.

Physical activity, screen time and subjective well-being among children / Actividad física, tiempo frente a la pantalla y bienestar subjetivo en niños

BACKGROUND/OBJECTIVE: The aim of the study was to explore the differences between physical activity and/or screen time levels on cognitive (Life satisfaction LS) and affective (Positive affect, PA and Negative affect NA) components of subjective well-being (SWB) in children. METHOD: This cross-sectional study enrolled 1,540 children (1,040 boys, 8-12 years old). LS, PA, NA, physical activity and screen time were assessed with validated questionnaires. RESULTS: Children who reported 3 days per week of physical activity or less had lower LS and PA than counterparts with ≥ 6 days of physical activity per week (p < .05). Participants who reported 2 hours per day or less of screen time had lower NA than counterparts with 4 hours per day or more of screen time (p < .05). Also, children who meet physical activity guidelines have higher LS and PA compared to inactive peers, even with high screen time. In contrast, excessive screen time was also related with NA independent of the level of physical activity. CONCLUSIONS: Our findings suggest that physical activity is related with positive feelings and LS, but does not eliminate the effect of screen time on negative feelings among Chilean children

INTRODUCCIÓN/OBJETIVO: Este estudio explora las diferencias entre la actividad física y/o los niveles de tiempo de pantalla en los componentes cognitivo (Satisfacción de la vida SV) y afectivo (Afecto positivo AP y Afecto negativo AN) del bienestar subjetivo en niños. MÉTODO: Se incluyó a 1.540 niños (1.040 niños, 8 a 12 años). La SV, AP, AN, actividad física y tiempo de pantalla se evaluaron con cuestionarios validados. RESULTADOS: Los niños que informaron 3 días/semana de actividad física o menos tenían menos SV y AP que sus homólogos con 6 días/semana de actividad física o más (p < 0,05). Los que informaron menos de 2 horas por día de tiempo de pantalla tuvieron menos AN que sus homólogos con más o igual a 4 horas por día de tiempo de pantalla (p < 0,05). Además, los niños que cumplen con las pautas de actividad física tienen mayor SV y AP en comparación con los inactivos, incluso con un tiempo de pantalla elevado. Por el contrario, el tiempo de pantalla excesivo también se relacionó con el AN independientemente del nivel de actividad física. CONCLUSIONES: Los hallazgos sugieren que la actividad física está relacionada con emociones positivas y SV, pero no elimina el efecto del tiempo de pantalla en las emociones negativas

Physical activity, screen time and subjective well-being among children.

BACKGROUND/OBJECTIVE: The aim of the study was to explore the differences between physical activity and/or screen time levels on cognitive (Life satisfaction LS) and affective (Positive affect, PA and Negative affect NA) components of subjective well-being (SWB) in children. METHOD: This cross-sectional study enrolled 1,540 children (1,040 boys, 8-12 years old). LS, PA, NA, physical activity and screen time were assessed with validated questionnaires. RESULTS: Children who reported 3 days per week of physical activity or less had lower LS and PA than counterparts with ≥6 days of physical activity per week (p < .05). Participants who reported 2 hours per day or less of screen time had lower NA than counterparts with 4 hours per day or more of screen time (p < .05). Also, children who meet physical activity guidelines have higher LS and PA compared to inactive peers, even with high screen time. In contrast, excessive screen time was also related with NA independent of the level of physical activity. CONCLUSIONS: Our findings suggest that physical activity is related with positive feelings and LS, but does not eliminate the effect of screen time on negative feelings among Chilean children.

INTRODUCCIÓN/OBJETIVO: Este estudio explora las diferencias entre la actividad física y/o los niveles de tiempo de pantalla en los componentes cognitivo (Satisfacción de la vida SV) y afectivo (Afecto positivo AP y Afecto negativo AN) del bienestar subjetivo en niños. MÉTODO: Se incluyó a 1.540 niños (1.040 niños, 8 a 12 años). La SV, AP, AN, actividad física y tiempo de pantalla se evaluaron con cuestionarios validados. RESULTADOS: Los niños que informaron 3 días/semana de actividad física o menos tenían menos SV y AP que sus homólogos con 6 días/semana de actividad física o más (p < 0,05). Los que informaron menos de 2 horas por día de tiempo de pantalla tuvieron menos AN que sus homólogos con más o igual a 4 horas por día de tiempo de pantalla (p < 0,05). Además, los niños que cumplen con las pautas de actividad física tienen mayor SV y AP en comparación con los inactivos, incluso con un tiempo de pantalla elevado. Por el contrario, el tiempo de pantalla excesivo también se relacionó con el AN independientemente del nivel de actividad física. CONCLUSIONES: Los hallazgos sugieren que la actividad física está relacionada con emociones positivas y SV, pero no elimina el efecto del tiempo de pantalla en las emociones negativas.

Physical fitness components in relation to attention capacity in Latin American youth with overweight and obesity.

The aim of the study was twofold: (a) to examine the association between health-related physical fitness and attention capacity in Latin American children and adolescents with overweight and obesity and (b) to test whether body composition outcomes are moderators of this association. A cross-sectional design was used to study 201 overweight/obese participants (12.1 ± 2.1 years of age; 34.3% girls) from Chile (Active-Start study) and Colombia (HEPAFIT study). Body composition, muscular fitness, speed-agility, and cardiorespiratory fitness were evaluated using two similar test batteries (ALPHA and FUPRECOL). Attention capacity was measured by the d2 Test. Linear regression and moderation analyses were conducted. Linear regression analysis revealed an association between muscular fitness (ß = 0.245, P = .015), speed-agility (ß = -0.16, P = .027), cardiorespiratory fitness (ß = 0.331, P < .001) and overall fitness score (ß = 0.210; P = .004) and attention capacity (all analyses were controlled for age, sex, peak height velocity, maternal education, and study setting). Moderation analysis using the Johnson-Neyman technique revealed that the effect of the relationship between muscular fitness score and speed-agility and attention capacity was stronger as fat mass and fat mass index increased. In conclusion, physical fitness components are associated with higher attention capacity in youth with overweight/obesity, but body composition seems to moderate these relationships. Randomized controlled trials in this population would help to better understand whether improvements in different components of physical fitness lead to better attention capacity, especially in youth with excess adiposity.

Exercise program and blood pressure in children: The moderating role of sedentary time.

OBJECTIVES: The aim of the present study was to test a before-school physical activity intervention (Active-Start intervention) on blood pressure in children and examine whether sedentary time moderates the effect of the intervention on blood pressure. DESIGN: Randomized controlled trial. METHODS: The Active-Start intervention comprising 170 children (8-10 years old) from three public schools with low socioeconomic status in Santiago (Chile). The exercise intervention was delivered daily, before starting the first school-class (8:00-8:30 a.m.), for 8 weeks. The intervention was mainly a program of cooperative physical games at moderate-vigorous intensity. Resting systolic and diastolic blood pressure was determined from the average of two measurements at baseline and at the end of intervention. Moderate-to-vigorous physical activity and sedentary time was assessed using a GENEActiv tri-axial accelerometer prior to the program intervention. RESULTS: The Active-Start intervention decreased blood pressure levels in children (p<0.01) but did not change relative to the control group. Johnson-Neyman analysis revealed a significant relationship between the effect of intervention on systolic blood pressure and mean arterial pressure when sedentary time was below, but not at or above, 657 and 659min per day (i.e., the effect of physical exercise disappears), respectively. CONCLUSIONS: The effect of physical activity on blood pressure could disappear in children with excessive sedentary time, which highlights the need to reduce total levels of sedentary time in the day-to-day life of young people in and out of schools.

A before-school physical activity intervention to improve cognitive parameters in children: The Active-Start study.

The aim of the study was threefold: (a) to test a before-school physical activity intervention (Active-Start) on academic performance, selective attention, and concentration capacity; (b) to test the effect of the Active-Start intervention on anthropometry, body composition, and physical fitness parameters; and (c) whether the physical fitness components are moderators of the effect of the Active-Start program on academic performance, selective attention, and concentration capacity in Chilean children. The Active-Start intervention was a RCT which comprised 170 children (8-10 years old) from three public schools with low socioeconomic status from the city of Santiago (Chile). The exercise intervention was delivered daily, before starting the first school-class (8:00-8:30 am) for 8 weeks. Changes in academic performance, selective attention and concentration capacity, anthropometric, body composition, and physical fitness parameters were measured. The analyses used were mixed regression models for repeated measures over time. No statistically significant changes in attention and concentration capacity were found. However, significant changes were seen in language (0.63; 95% CI 0.49-0.77) and mathematics (0.49; 95% CI 0.32-0.66) performance (P < .001). Also, improvements were seen in fat mass, fat-free mass, muscular, and cardiorespiratory fitness (all P < .05). The Johnson-Neyman technique revealed a significant relationship between the effect of intervention and attention and concentration when change in cardiorespiratory fitness was above, but not below, 3.05 and 0.70 mL/kg/min, respectively. Implementing before-school physical activity programs such as the Active-Start to enhance the cardiorespiratory fitness may benefit attention capacity and academic success among schoolchildren.

Can a before-school physical activity program decrease bullying victimization in disadvantaged children? The Active-Start Study.

BACKGROUND/OBJECTIVE: To test the effectiveness of an 8-week before-school physical activity program to reduce bullying victimization among a group of socially disadvantaged children in the Active-Start study. METHOD: A non-blinded randomized controlled trial was conducted in three public schools classified as highly vulnerable and located in a deprived area of Santiago (Chile). A total of 5 classes participated, totaling 170 fourth grade children. The intervention was delivered before starting the first school-class (8:00-8:30 a.m.). The program lasted for 8 weeks. Primary outcome measurement on bullying victimization was assessed by the CUBE questionnaire at baseline and post-intervention. RESULTS: There was a statistically significant reduction in the probability of suffering physical bullying (OR= 0.18, 95% CI, 0.04-0.82; p= .027) and verbal bullying (OR=0.13, 95% CI, 0.02-0.97; p= .046) after the 8-week program. CONCLUSIONS: Participation in an 8-week before-school physical activity intervention implemented in schools located in a disadvantaged district in Santiago (Chile) resulted in lower levels of bullying victimization among study participants. The Active-Start program may be a feasible and potentially scalable intervention option to improve the climate and pro-sociality environment at schools.

ANTECEDENTES/OBJETIVO: Evaluar la efectividad de un programa de actividad física antes de la escuela de ocho semanas para reducir el bullying en niños en desventaja social del estudio Active-Start. MÉTODO: Se realizó un ensayo controlado aleatorio no ciego en tres escuelas públicas vulnerables y ubicadas en Santiago (Chile), con un total de cinco clases e incluyendo 170 niños de Cuarto Grado. La intervención de ocho semanas se realizó cinco veces por semana antes de comenzar la primera clase (8:00­8:30 a.m.). La medida de resultado primaria fue la victimización por bullying evaluado a través del cuestionario CUBE al inicio y después de la intervención. RESULTADOS: Hubo una reducción estadísticamente significativa en la probabilidad de sufrir bullying físico (OR= 0,18, IC 95%, 0,04-0,82; p= 0,027) y verbal (OR= 0,13, IC 95%, 0,02-0,97; p= 0,046) después del programa de ocho semanas. CONCLUSIONES: La participación en una intervención de actividad física antes de la escuela de ocho semanas implementada en escuelas ubicadas en una comuna desfavorecida en Santiago (Chile) dio lugar a niveles más bajos de victimización por bullying entre sus participantes. El programa Active-Start puede ser una opción de intervención viable y potencialmente escalable para mejorar el clima y el ambiente escolar.

Can a before-school physical activity program decrease bullying victimization in disadvantaged children? The Active-Start Study / ¿Puede un programa de actividad física antes de la escuela disminuir la victimización por bullying en niños desfavorecidos? Estudio Active-Start

Background/Objective: To test the effectiveness of an 8-week before-school physical activity program to reduce bullying victimization among a group of socially disadvantaged children in the Active-Start study. Method: A non-blinded randomized controlled trial was conducted in three public schools classified as highly vulnerable and located in a deprived area of Santiago (Chile). A total of 5 classes participated, totaling 170 fourth grade children. The intervention was delivered before starting the first school-class (8:00-8:30 a.m.). The program lasted for 8 weeks. Primary outcome measurement on bullying victimization was assessed by the CUBE questionnaire at baseline and post-intervention. Results: There was a statistically significant reduction in the probability of suffering physical bullying (OR= 0.18, 95% CI, 0.04-0.82; p= .027) and verbal bullying (OR=0.13, 95% CI, 0.02-0.97; p= .046) after the 8-week program. Conclusions: Participation in an 8-week before-school physical activity intervention implemented in schools located in a disadvantaged district in Santiago (Chile) resulted in lower levels of bullying victimization among study participants. The Active-Start program may be a feasible and potentially scalable intervention option to improve the climate and pro-sociality environment at schools

Antecedentes/Objetivo: Evaluar la efectividad de un programa de actividad física antes de la escuela de ocho semanas para reducir el bullying en niños en desventaja social del estudio Active-Start. Método: Se realizó un ensayo controlado aleatorio no ciego en tres escuelas públicas vulnerables y ubicadas en Santiago (Chile), con un total de cinco clases e incluyendo 170 niños de Cuarto Grado. La intervención de ocho semanas se realizó cinco veces por semana antes de comenzar la primera clase (8:00-8:30 a.m.). La medida de resultado primaria fue la victimización por bullying evaluado a través del cuestionario CUBE al inicio y después de la intervención. Resultados: Hubo una reducción estadísticamente significativa en la probabilidad de sufrir bullying físico (OR= 0,18, IC 95%, 0,04-0,82; p= 0,027) y verbal (OR= 0,13, IC 95%, 0,02-0,97; p= 0,046) después del programa de ocho semanas. Conclusiones: La participación en una intervención de actividad física antes de la escuela de ocho semanas implementada en escuelas ubicadas en una comuna desfavorecida en Santiago (Chile) dio lugar a niveles más bajos de victimización por bullying entre sus participantes. El programa Active-Start puede ser una opción de intervención viable y potencialmente escalable para mejorar el clima y el ambiente escolar

Independent and combined effects of handgrip strength and adherence to a Mediterranean diet on blood pressure in Chilean children.

OBJECTIVE: The aim of the study was to examine the combined associations between handgrip strength (HGS) and adherence to a Mediterranean diet with blood pressure (BP) in Chilean children. METHODS: This cross-sectional study enrolled 1140 children (794 boys and 346 girls) 8 to 12 y of age. HGS was measured using a hand dynamometer with an adjustable grip. Adherence to a Mediterranean diet was assessed with the Kidmed score. Resting BP was measured by an automated monitor using an appropriately sized cuff. Elevated BP was defined as ≥90th percentile, and high HGS was defined as sex- and age-specific normative ≥80th percentile for the HGS. RESULTS: The prevalence of elevated systolic BP, diastolic BP, and overall BP were 16.6%, 12.9%, and 8.1%, respectively. HGS was negatively associated with BP parameters in an unadjusted and adjusted model after considering potential confounders (age, sex, body mass index z-score, and HGS). Regarding diet adherence, the unadjusted model reveals that children with high adherence to the Mediterranean diet showed lower BP levels (systolic, diastolic, and mean arterial pressure) compared with children with low-medium adherence; however, these differences disappear after considering potential confounders. The combination of high HGS and optimal adherence to a Mediterranean diet was negatively associated with BP. CONCLUSIONS: Children with a high HGS levels (i.e., ≥80th percentile) may somewhat overcome the deleterious effects of low adherence to a Mediterranean diet. Therefore, these findings suggest that the combination of these two components of a healthy lifestyle, especially HGS may be beneficial to children's BP.