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Objective: To examine the associations of self-perceived and objectively-measured physical fitness with psychological well-being and distress indicators in young pediatric cancer survivors. Materials and Methods: A total of 116 participants (12.1 ± 3.3 years, 56.9% boys) from the iBoneFIT project participated in this cross-sectional study. Objectively-measured physical fitness (muscular fitness) was obtained by handgrip strength and standing long jump tests for the upper and lower body, respectively. Self-perceived physical fitness was obtained by the International Fitness Scale (IFIS). Positive and negative affect were assessed by the positive affect schedule for children (PANAS-C), happiness by Subjective Happiness Scale (SHS), optimism by Life Orientation Test-Revised (LOT-R), self-esteem by the Rosenberg Self-Esteem Scale (RSE), anxiety by State–Trait Anxiety Inventory for Children (STAIC-R), and depression by Children Depression Inventory (CDI). Multiple linear regressions adjusted by key covariates were performed to analyze associations. Results: No associations were found between objectively-measured muscular fitness and any of the psychological well-being and distress indicators (p > 0.05). Self-perceived overall fitness and flexibility were positively associated with positive affect (β ≥ 0.258, p < 0.05). Self-perceived cardiorespiratory fitness, speed/ agility, and flexibility were negatively associated with depression (β ≥ −0.222, p < 0.05). Finally, self-perceived cardiorespiratory fitness was also negatively associated with anxiety and negative affect (β ≥ −0.264, p < 0.05). Conclusions: Perceived physical fitness, but not objectively physical fitness, seems to be inversely related to psychological distress variables and to less extent positively related to psychological well-being. The findings from this study highlight the importance of promoting self-perceived fitness in the pediatric oncology population., Ministry of Science and Innovation, Spain (MICINN) Spanish Government PID2020-117302RA-I00, La Caixa Foundation LCF/BQ/PR19/11700007, European Union's Horizon 2020 research and inno-vation programme under the Marie Sklodowska Curie 101028929

IMPORTANCE Excess abdominal fat is a major determinant in the development of insulin resistance and other metabolic disorders. Increased visceral adipose tissue (VAT) seems to precede the development of insulin resistance and is therefore a prime target of childhood lifestyle interventions aimed at preventing diabetes. OBJECTIVES To examine the effect of added exercise to a family-based lifestyle intervention program designed to reduce VAT plus subcutaneous (ASAT), intermuscular (IMAAT), and pancreatic (PAT) adipose tissue in children with overweight or obesity and to explore the effect of changes in VAT on insulin resistance. DESIGN, SETTING, AND PARTICIPANTS This 2-group, parallel-design clinical trial was conducted in Vitoria-Gasteiz, Spain. A total of 116 children with overweight or obesity participated and were assigned to a 22-week family-based lifestyle program (control group [n = 57]) or the same program plus an exercise intervention (exercise group [n = 59]). Data were collected between September 1, 2014, and June 30, 2017, and imaging processing for fat depot assessments and data analysis were performed between May 1, 2019, and February 12, 2021. INTERVENTIONS The compared interventions consisted of a family-based lifestyle and psychoeducation program (two 90-minute sessions per month) and the same program plus supervised exercise (three 90-minute sessions per week). MAIN OUTCOMES AND MEASURES The primary outcome of this study was the change in VAT between baseline and 22 weeks as estimated by magnetic resonance imaging. The secondary outcomes were changes in ASAT, IMAAT, and PAT. The effect of changes in VAT area on insulin resistance was also recorded. RESULTS The 116 participants included in the analysis (62 girls [53.4%]) had a mean (SD) age of 10.6 (1.1) years, and 67 (57.8%) presented with obesity. Significantly greater reductionswere recorded for the exercise group in terms of reduction in VAT (−18.1%vs −8.5%for the control group; P = .004), ASAT (−9.9%vs −3.0%; P = .001), and IMAAT (−6.0%vs −2.6%; P = .02) fat fractions compared with the control group. Changes in VAT explained 87.6%of the improvement seen in insulin resistance (β = −0.102 [95%CI, −0.230 to −0.002]). CONCLUSIONS AND RELEVANCE These findings suggest that the addition of exercise to a lifestyle intervention program substantially enhanced the positive effects on abdominal fat depots in children with overweight or obesity. In addition, the reduction in VAT seemed to largely mediate the improvement of insulin sensitivity. These results highlight the importance of including exercise as part of lifestyle therapies aimed at treating childhood obesity and preventing the development of type 2 diabetes., Spanish Ministry of Health's Fondos de Investigacion Sanitaria del Instituto de Salud Carlos III PI13/01335 Spanish Government DEP2016-78377, European Commission 0011-1365-2019-000085, Regional Government of Navarra's Department of Economic Development - ERDF Government of Navarra's Department of Health 47/2021, Ministry of Science and Innovation, Spain (MICINN) Spanish Government FJC2018-037925-I, Marie Sklodowska Curie 101028929 European Commission, Education Department of the Government of the Basque Country BES-2017-080770 PRE_2016_1_0057 PRE_2017_2_0224 PRE_2018_2_0057 PRE_2019_2_0004, Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades, ERDF SOMM17/6107/UGR

The aims of this study were to describe patterns of active commuting to school (ACS) of preschool children, and to analyse the relationship between ACS and family socio-economic factors. A total of 2636 families of preschoolers (3-to-5 years old) were asked to complete a questionnaire at home about the mode of commuting to school of their children and marital status, educational level, and profession of both father and mother. Chi-square analyses were applied to compare ACS between school grades and gender of the children. To analyse the association of ACS with socio-economic factors, logistic regression analyses were performed. Almost 50% of participants reported ACS of their offspring, with a higher rate in 3rd preprimary grade (5 years old) than in 1st and 2nd preprimary grades (3- and 4-years old. All, p < 0.05). Those preschool children who had parents with lower educational level and no managerial work had higher odds to ACS than those who had parents with higher educational level and managerial work (all, p ≤ 0.001). Around half of the Spanish preschool children included in this study commuted actively to school and families with lower educational levels or worse employment situation were related to active commuting to school., Spanish Ministry of Economy, Industry and Competitiveness and the European Regional Development Fund (DEP2016-75598-R, MINECO/FEDER, UE), University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES), Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Fund (ERDF: ref SOMM17/6107/UGR), Spanish Ministry of Science and Innovation (FJC2018-037925-I).

La evaluación de la condición física tradicionalmente ha estado vinculada al paradigma de rendimiento, que ha orientado la calificación hacia la eficacia del estudiante. El presente estudio tiene como objeto analizar la capacidad cardiorrespiratoria en adolescentes de Cá- diz (España). Además, este trabajo aporta una calculadora de rendimiento y esfuerzo para guiar la evaluación formativa de la capacidad cardiorrespiratoria y aportar orientaciones metodológicas para su aplicación en el ámbito escolar. Participaron 323 estudiantes de entre 12 y 19 años (Medad=14.68; ±1.75), 168 chicos (52%) y 155 chicas (48%). Se valoró la capacidad cardiorrespiratoria a través del test de 20 metros de ida y vuelta al que se le incorporó pistas de audio. Los participantes fueron monitorizados con un pulsómetro (ONrhythm 500) y respondieron a una escala de percepción de esfuerzo (Borg, escala 1-10). Los valores medios para las variables analizadas fueron: último estadío completado, 5.92 (±2.47); frecuencia cardíaca (FC) máxima, 198.02 (±0.71); diferencia entre la FC máxima teórica y real, -0.33 (±11.05); percepción de esfuerzo, 7.87 (±2.03). A partir de los resultados obtenidos se elaboró una calculadora para estimar el esfuerzo y orientar el análisis del rendimiento. Se espera que sea una herramienta útil para los profesores de Educación Física e investigadores para calcular el nivel de condición cardiorrespiratoria, estimar el esfuerzo y analizar el nivel de riesgo de padecer una enfermedad cardiovascular Physical fitness assessment has traditionally been linked to a performance paradigm, which has oriented the grades towards student effectiveness. The present study aims to analyze the cardiorespiratory capacity in adolescents from Cadiz (Spain). In addition this work provides a performance and effort tool to guide formative and shared assessment of cardiorespiratory fitness and to provide methodological guidance for its application in the school setting. Students. A total of 323 students between 12 and 19 years (mean age 14.68; ±1.75), 168 boys (52%) and 155 girls (48%). Cardiorespiratory capacity was assessed by an adaptation of the original 20-meter shuttle run test, which consisted on including music. Participants were monitored with a heart rate monitor (ONrhythm 500) and registered the Borg rating of perceived exertion scale (1-10). Mean values for the variables analyzed were: last completed stage, 5.92 (±2.47); maximum heart rate, 198.02 (±0.71); difference between theoretical and real maximum HR, -0.33 (±11.05); perception of effort, 7.87 (±2.03). Based on the results obtained, a calculator was developed to estimate effort and provide guidance in performance analysis. It is elaborated to be a useful tool for Physical Education teachers and researchers to assess cardiorespiratory fitness, estimate the effort and to analyze the risk of future cardiovascular disease.

The aim of this study was to examine whether metabolically healthy overweight/obese children have greater global and regional gray matter volumes than their metabolically unhealthy peers. We further examined the association between gray matter volume and academic achievement, along with the role of cardiorespiratory fitness in these associations. A total of 97 overweight/obese children (10.0 ± 1.2 years) participated. We classified children as metabolically healthy/unhealthy based on metabolic syndrome cut-offs. Global and regional brain volumes were assessed by magnetic resonance imaging. Academic achievement was assessed using the Woodcock-Muñoz standardized test. Cardiorespiratory fitness was assessed by the 20 m shuttle run test. Metabolically healthy overweight/obese (MHO) children had greater regional gray matter volume compared to those who were metabolically unhealthy (MUO) (all p ≤ 0.001). A similar trend was observed for global gray matter volume (p = 0.06). Global gray matter volume was positively related to academic achievement (β = 0.237, p = 0.036). However, all the associations were attenuated or disappeared after adjusting for cardiorespiratory fitness (p > 0.05). The findings of the present study support that metabolically healthy overweight/obese children have greater gray matter volume compared to those that are metabolically unhealthy, which is in turn related to better academic achievement. However, cardiorespiratory fitness seems to explain, at least partially, these findings., The ActiveBrains project was funded by the Spanish Ministry of Economy and Competitiveness and the "Fondo Europeo de Desarrollo Regional (FEDER)" (DEP2013-47540, DEP2016-79512-R, DEP2017-91544-EXP and RYC-2011-09011). CC-S are supported by the Government of Andalusian, Integrated Territorial Initiative 2014-2020 for the province of Cadiz (PI-0002-2017) and the Spanish Ministry of Science and Innovation (FJC2018-037925-I). IE-C are supported by the Alicia Koplowitz Foundation and the Spanish Ministry of Economy and Competitiveness (RTI2018-095284-J-100). JHM and JM-G are supported by the Spanish Ministry of Education, Culture and Sport (FPU15/02645 and FPU14/06837, respectively). JVR is supported by a grant from the Spanish Ministry of Science, Innovation and Universities (FJCI-2017-33396). PH was supported by a grant from the Strategic Research Area Health Care Science, Karolinska Institutet/Umea University. Additional funding was obtained from the University of Granada, Plan Propio de Investigacion 2016, Excellence actions: Units of Excellence; Scientific Excellence Unit on Exercise and Health (UCEES). Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades and European Regional Development Funds (ref. SOMM17/6107/UGR). In addition, funding was provided by the SAMID III network, RETICS, funded by the PN I + D + I 2017-2021 (Spain), ISCIII-Sub-Directorate General for Research Assessment and Promotion, the European Regional Development Fund (ERDF) (Ref. RD16/0022), the EXERNET Research Network on Exercise and Health in Special Populations (DEP2005-00046/ACTI) and the European Union's 2020 research and innovation program under grant agreement No 667302.

The aims of this study were (i) to examine the association between cardiorespiratory fitness and white matter volume and test whether those associations differ between normal-weight and overweight/obese children (ii) to analyze the association between other physical fitness components (i.e., motor and muscular) and white matter volume, and (iii) to examine whether the fitness-related associations in white matter volume were related to academic performance. Data came from two independent projects: ActiveBrains project (n = 100; 10.0 1.1 years; 100% overweight/obese; Spain) and FITKids2 project (n = 242; 8.6 0.5 years; 36% overweight/obese, United States). Cardiorespiratory fitness was assessed in both projects, and motor and muscular fitness were assessed in the ActiveBrains project. T1-weighted images were acquired with a 3.0 T S Magnetom Tim Trio system. Academic performance was assessed by standardized tests. Cardiorespiratory fitness may positively relate to white matter volume in overweight/obese children, and in turn, academic performance. In addition, motor and muscular fitness may also influence white matter volume coupled with better academic performance. From a public health perspective, implementing exercise interventions that combine aerobic, motor and muscular training to enhance physical fitness may benefit brain development and academic success, The ActiveBrains study was supported by the Spanish Ministry of Economy and Competitiveness (DEP2013-47540, DEP2016- 79512-R, and PSI2012-3929). The FITKids2 study was supported by a grant from the National Institutes of Health (HD069381).

The major aims of the present International Doctoral Thesis were: provide new methods for physical fitness assessment in preschool children, and provide reference standards for interpreting fitness assessment (Section 1); and to examine the associations between physical fitness and academic achievement in preadolescent children, as well as to explore the role of metabolic healthy overweight/obesity phenotype in the brain and its associations with academic achievement (Section 2). To address these aims, nine studies were conducted in the context of two projects. The PREFIT project (Section 1, Studies I to VII) is a cross-sectional study that takes place in 2 stages: first, a methodological stage conducted in Granada and a second, a multi-center stage carried out in more than 3000 Spanish pre-schoolers from 10 Spanish cities, for a better understanding of physical fitness assessment in this age group. The ActiveBrains project (Section 2, Studies VIII to IX) is a randomized controlled trial that aimed to examine the effect of physical exercise programme on physical and mental health in overweight/obese children. The present Thesis focused on cross-sectional analyses using the baseline data. The main findings and conclusions derived from the nine studies included in this thesis were: I) The PREFIT battery hereby proposed is based on the output of the current systematic review in preschool children; II) The intra-instrument test–retest reliability was excellent for all of the dynamometers used for handgrip strength assessment in the PREFIT battery; III) The PREFIT 20m shuttle run test is feasible, maximum and reliable in preschool children; IV) The PREFIT battery is a feasible and reliable tool to assess physical fitness in preschool children yet standing long jump has shown mixed findings. The one-leg stance test showed poor reliability in our study, not supporting thus its use in 3 to 5 years-old; V and VI) We provide reference standards for physical fitness and anthropometry by sex and age from a relatively large sample of preschool children geographically distributed across Spain; and VII) Higher prevalence of overweight/obesity in Spain compared with Sweden is present already at early childhood, while differences in physical fitness components showed mixed findings. In regards to the Section 2, the main findings were: VIII) Not only cardiorespiratory fitness but also muscular strength and speed-agility were positively associated with academic achievement in overweight/obese children. Physical activity did not demonstrate an association with any of the academic outcomes studied; and IX) Metabolically healthy overweight/obesity related to higher gray matter volume and total brain volume compared to metabolically unhealthy overweight/obese children, which in turn related to better academic achievement, although such associations disappeared or were attenuated after adjusting for cardiorespiratory fitness. The results of this International Doctoral Thesis enhance our understanding about how to assess and interpret physical fitness and fatness in preschool children; and also how physical fitness relate with academic achievement and the metabolically healthy overweight/obesity phenotype with brain in preadolescent children. These results will lead to future prospective and intervention investigations on the physical and brain health at childhood and later in life., Tesis Univ. Granada., Programa Oficial de Doctorado en Biomedicina

Previous studies have shown that physical activity, fitness and academic achievement might predict cognitive performance later in life . However, to the best of our knowledge, there are no studies examining the inverse relationship, that is, whether cognition may predict fitness and academic achievement in adolescents one year later . Therefore, the aim of this study was to examine the associations between cognitive performance and physical fitness and academic achievement one year later . Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

El objetivo de este estudio fue comparar las variables cinemáticas de la marcha (hacia adelante -AD- y hacia atrás-AT-) en el medio terrestre y en el medio acuático. Ocho adultos (22.12 ± 1.13 años) realizaron el protocolo con el objeto de cubrir una distancia de 10 metros a velocidad confortable y con una frecuencia de paso controlada. Se colocaron marcadores reflectantes en las extremidades inferiores y, posteriormente, se digitalizaron para obtener información cinemática. En agua los valores de la velocidad, longitud de ciclo, longitud de paso y duración de la fase de soporte fueron menores mientras que los de simetría de longitud de paso fueron mayores (p, The aim of this study was to compare lower limbs and center of mass kinematics during walking (forward –FW- and backward –BW-) on land and in shallow water. Eight healthy adults (22.12 ± 1.13 years) performed the protocol to cover a distance of 10m at comfortable speed with controlled step frequency. Reflective markers were placed on the lower limbs and digitalized later to obtain kinematics information. In water the values of speed, stride length, step length and support phase were lower whilst those of symmetry of step length were greater (p, Universidad de Granada. Máster Universitario en Investigación de Actividad Física y Deporte

The purpose of this study was to describe anthropometric and physical fitness characteristics of low-income Chilean preschool children and to examine whether weight status influences children’s performance on fitness tests. A total of 434 preschool children (246 boys; 5.48 ± 0.31 years) participated in our study. Anthropometry (weight, height, body mass index -BMI- and waist circumference) and fitness tests (handgrip strength test, standing long jump and 20 m sprint) were assessed by trained nutritionists and physical education teachers, respectively. Significant differences in anthropometry and fitness tests between boys and girls were found. The prevalence of overweight was higher in girls; in contrast to that of obesity. Compared to normal-weight children, overweight/obese boys and girls were heavier and had greater waist circumference (P < 0.001), were taller (P ≤ 0.002), and showed higher performance in handgrip strength (P ≤ 0.027) but not in standing long jump nor 20 m sprint (P ≥ 0.052). Screening physical fitness levels in overweight/obese preschool children could be an important tool in order to design an efficacy physical activity programme., El objetivo de este estudio fue describir las características antropométricas y el nivel de condición física de preescolares chilenos de bajo nivel socioeconómico y examinar si el estado ponderal influye en el rendimiento de los niños en las pruebas de condición física. Un total de 434 preescolares (246 niños; 5,48 ± 0,31 años) participaron en nuestro estudio. Antropometría (peso, talla, índice de masa corporal –IMC– y perímetro de cintura) y tests de condición física (test de fuerza de prensión manual, test de salto de longitud y 20 m sprint) fueron evaluados por nutricionistas entrenados y profesores de educación física, respectivamente. Se encontraron diferencias significativas en antropometría y tests de condición física entre niños y niñas. La prevalencia de sobrepeso fue mayor en las niñas; en contraste con la de la obesidad. En comparación con los preescolares con normopeso, los niños y niñas con sobrepeso/obesidad pesaron más y tuvieron mayor perímetro de cintura (P < 0.001), eran más altos (P ≤ 0.002) y mostraron mayor rendimiento en el test de fuerza de prensión manual (P ≤ 0.027), pero no en el test de salto de longitud ni en el test de sprint de 20 m (P ≥ 0.052). Detectar los niveles de condición física en preescolares con sobrepeso/obesidad puede ser una herramienta importante para diseñar programas eficaces de actividad física., They would like to thank the “Corporación Municipal de Educación y Salud” of Ñuñoa for funding the study. Likewise, we thank Francisco B. Ortega from the University of Granada, Spain, for his valuable comments on an earlier draft. Cristina Cadenas-Sánchez is supported by a grant from the Spanish Ministry of Economy and Competitiveness (BES-2014-068829).

La capacidad cardiorrespiratoria es un potente indicador de salud presente y futura en niños y adolescentes, sin embargo se desconoce si también lo es para niños de edad preescolar, de 3 a 5 años. En el presente estudio, describimos la adaptación a preescolares del test original de 20m de ida y vuelta, su viabilidad y asimilación en niños de 3 a 5 años, así como su maximalidad y fiabilidad. Un total de 130 alumnos (4,91 ± 0,89 años; 77 niños), realizaron el test dos veces, con dos semanas de separación. La adaptación del test consistió principalmente en reducir la velocidad inicial de 8,5 km/h a 6,5 km/h. El test fue viable y tuvo una buena asimilación tanto en niños como en niñas y en los tres grupos de edad, 3, 4 y 5 años. La frecuencia cardíaca máxima (FCmáx) alcanzada para la muestra completa fue de 199,4 ± 12,5 latidos/minuto, equivalente a un 97% de la FCmáx teórica estimada, y sin diferencias significativas por sexo o edad. La diferencia de medias test-retest (error sistemático) en el número de vueltas alcanzado fue de 2 vueltas, sin diferencias por sexo o edad. No hubo evidencia de heterocedasticidad. Nuestros resultados sugieren que el test es máximo y fiable en este grupo de edad. Futuros estudios de intervención o longitudinales que utilicen este test deberían tener en cuenta que cambios en el rendimiento en el test de 2 vueltas podrían deberse a la propia variabilidad de la medida, mientras que cambios de mayor magnitud podrían ser atribuibles a la intervención o cambios asociados a la edad., Cardiorespiratory fitness is a strong indicator of present and future health in children and adolescents, however it is unknown whether it is for pre-schoolers, from 3 to 5 years. In the present study, we described the adaptation of the original 20m shuttle run test, it feasibility and acceptance in children from 3 to 5 years and its maximality and reliability. A total of 130 students (4.91 ± 0.89 years; 77 boys) performed the test twice, two weeks apart. The test adaptation consisted mainly in reducing the initial speed of 8.5 km/h to 6.5 km/h. The test was feasible and was well accepted in both boys and girls and the three age groups, 3, 4 and 5 years. The maximum heart rate (MHR) achieved for the entire sample was 199.4 ± 12.5 beats/min, equivalent to 97% of the estimated theoretical MHR, and no significant differences by gender or age. Mean test-retest difference (systematic error) in the number of laps achieved was 2 laps, with no significant differences between sex or age. There was no evidence of heteroscedasticity. Our results suggest the test is maximum and reliable in this age group. Future longitudinal or intervention studies using this test should take into account that changes in the test performance of 2 laps may be due to the variability of the measure, while wider changes would be attributable to the intervention or changes associated with age.

Resumen basado en el de la publicación Se presenta una experiencia en la que se ha llevado a cabo un programa de 'mentorización' de dos profesores noveles de la Facultad de Ciencias del Deporte de la Universidad de Granada, mediante una entrevista personal previa entre mentora y profesores. Posteriormente, se ha realizado un ciclo de mejora tratando de detectar los puntos débiles de cada uno de los principiantes, y también a través de varios talleres y seminarios organizados en el programa de formación, se buscaba evolución, obteniendo como resultado cambios favorables en su labor docente, mejora en cuanto a la organización, gestión y control de sus clases, así como en lo referente a la forma de llevar a cabo sus exposiciones. Con esta experiencia se ha conseguido dotar a estos docentes de una mayor seguridad en sí mismos y una mejor gestión, organización y puesta en práctica de sus clases, mejorando de este modo, su labor docente. Andalucía ESP

Background: The prevalence of childhood obesity worldwide is currently at extremely high levels and it is known to be linked to a myriad of health-related problems, among them, a poor sleep health or sleep-disordered breathing. It is important to investigate factors that could fight against obesity consequences and physical exercise emerges as a strong candidate. Objectives and methods: The present International Doctoral Thesis aims to examine the role of sleep-related outcomes in relation to physical and brain health (section 1), to study the effects of a physical exercise program on sleep-related outcomes in children with overweight or obesity (section 2), and to investigate the impact of fatness and cardiorespiratory fitness on sleep-disordered breathing after 1-year of follow-up in children (section 3). Six studies were conducted within the three sections: four cross sectional studies (section 1), one randomized clinical trial (section 2) and one prospective cohort study (section 3). Main findings: Results from this Doctoral Thesis are described below. Television viewing time, cardiorespiratory fitness, and most adiposity markers were associated with sleep-disordered breathing, being the body mass index and television viewing time the best predictors of sleep-disordered breathing in children with overweight or obesity (study 1). Sleep-disordered breathing severity was related to: i) lower school grades (which was driven by inattention/hyperactivity), but not with standardized measurement of academic performance or brain structure (study 2), ii) worse behavioral and emotional functioning (i.e., higher external and internal problems and lower adaptability skills) (study 3), and iii) higher C-reactive protein levels independently of the adiposity levels, but not to other cardiometabolic or inflammatory risk factors in children with overweight or obesity (study 4). This study also suggested that higher levels of cardiorespiratory fitness might attenuate the adverse effect of sleep-disordered breathing on C-reactive protein. In addition, a 20-week physical exercise program reduced the time wakening after sleep onset in children with overweight or obesity in comparison with control group peers, yet effects were not observed on sleep-disordered breathing (study 5). Further, although not statistically significance, all device-assessed sleep outcomes were improved in those days in which the participants attended to the physical exercise session, suggesting acute effects of exercise on sleep-related outcomes. Lastly, severe/morbid obesity, central obesity and low fitness were linked to higher risk of sleepdisordered breathing at baseline in children, but 1-year longitudinal analyses did not show significant associations (study 6). Conclusion: Collectively, the main findings of the present International Doctoral Thesis shed light on the importance of improving sleep-related outcomes in children with overweight or obesity as a strategy to enhance physical and brain health. The use of physical exercise as a tool to improve children’s sleep health and sleep-disordered breathing with overweight or obesity is promising and warrants further investigation, Contexto: La prevalencia de obesidad infantil en todo el mundo es actualmente muy alta y se sabe que está relacionada con una serie de problemas de salud, entre ellos, patrones de sueño poco saludables o trastornos respiratorios del sueño. Es importante investigar factores que puedan combatir las consecuencias de la obesidad y el ejercicio físico emerge como un firme candidato. Objetivos y métodos: La presente Tesis Doctoral Internacional tiene como objetivos examinar el papel que juegan las diferentes variables de sueño en relación con la salud física y cerebral (sección 1), estudiar los efectos de un programa de ejercicio físico en las variables relacionadas con el sueño en niños y niñas con sobrepeso u obesidad (sección 2), e investigar el impacto de la obesidad y la capacidad cardiorrespiratoria en los trastornos respiratorios del sueño después de 1 año en niños y niñas (sección 3). Se realizaron seis estudios dentro de las tres secciones: cuatro estudios transversales (sección 1), un ensayo clínico aleatorizado (sección 2) y un estudio prospectivo de cohortes (sección 3). Resultados principales: Los resultados de esta Tesis Doctoral se describen a continuación. El tiempo viendo la televisión, la capacidad cardiorrespiratoria y la mayoría de los marcadores de adiposidad se asociaron con los trastornos respiratorios del sueño, siendo el índice de masa corporal y el tiempo viendo la televisión los que mejor explican los trastornos respiratorios del sueño en niños y niñas con sobrepeso u obesidad (estudio 1). La gravedad de los trastornos respiratorios del sueño se relacionó con: i) peores calificaciones escolares (debido a la falta de atención e hiperactividad), pero no con medidas estandarizadas de rendimiento académico o estructura cerebral (estudio 2), ii) peor funcionamiento conductual y emocional (es decir, mayores problemas de externalización e internalización, y menores habilidades de adaptación) (estudio 3), y iii) niveles más altos en sangre de proteína C-reactiva independientemente de los niveles de adiposidad, pero no con otros factores de riesgo cardiometabólico o inflamatorio en niños y niñas con sobrepeso u obesidad (estudio 4). Este estudio también sugirió que unos niveles más altos de capacidad cardiorrespiratoria podrían atenuar el efecto adverso de los trastornos respiratorios del sueño sobre la proteína C-reactiva. Además, un programa de ejercicio físico de 20 semanas redujo el tiempo de vigilia tras el inicio del sueño en niños y niñas con sobrepeso u obesidad en comparación con sus compañeros y compañeras del grupo control, aunque no se observaron efectos sobre los trastornos respiratorios del sueño (estudio 5). Así mismo, aunque sin significación estadística, todas las variables de sueño evaluadas mediante dispositivos mejoraron en los días en que los participantes asistieron a la sesión de ejercicio físico, lo que sugiere efectos agudos del ejercicio sobre las distintas variables relacionadas con el sueño. Por último, la obesidad severa/mórbida, la obesidad central y la baja forma física se relacionaron con un mayor riesgo de trastornos respiratorios del sueño al inicio del estudio en niños y niñas, pero los análisis longitudinales de 1 año no detectaron asociaciones significativas (estudio 6). Conclusión: En conjunto, los principales hallazgos de la presente Tesis Doctoral Internacional arrojan luz sobre la importancia de mejorar las distintas variables relacionadas con el sueño en los niños y niñas con sobrepeso u obesidad como estrategia para mejorar la salud física y cerebral. El uso del ejercicio físico como herramienta para mejorar la salud del sueño y los trastornos respiratorios del sueño de los niñas y niñas con sobrepeso u obesidad es prometedor y merece una mayor investigación., Tesis Univ. Granada., Spanish Ministry of Economy and Competitiveness and Fondo Europeo de Desarrollo Regional (FEDER) (DEP-2013-47540, DEP2016-79512-R, DEP2017-91544- EXP, BES-2014-068829, FJCI- 2014-19563, IJCI-2017-33642, and RYC-2011-09011)., University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence, Unit of Excellence on Exercise and Health (UCEES). Visiting Scholar., Junta de Andalucía, Conserjería de Conocimiento, Investigación y Universidades and European Regional Development Fund (ERDF) (SOMM17/6107/UGR)., Horizon 2020 Framework Programme, Grant/ Award Number: 667302., EXERNET Research Network on Exercise and Health., Andalusian Operational Programme supported with European Regional Development Funds (ERDF in English, FEDER in Spanish, project ref: B-CTS-355-UGR18).

Antecedentes: La obesidad infantil, es un problema de gran magnitud. Está ligada a múltiples comorbilidades, entre ellas la esteatosis hepática no alcohólica (HGNA), siendo actualmente una de las enfermedades hepáticas principales en población pediátrica con sobrepeso. Objetivo: Esta revisión sistemática, tratará de evaluar si los programas de actividad física son útiles como línea de tratamiento para disminuir el porcentaje de grasa hepática en niños y niñas con HGNA. Metodología: Para la búsqueda de artículos, se realizó revisión sistemática de evidencia científica en PubMed y Web of Science. Los siguientes términos fueron incluidos en la estrategia de búsqueda: child, non-alcoholic fatty liver disease (NAFLD), obesity, exercise, intervention. La búsqueda incluyó todos los artículos publicados hasta el 17 de febrero de 2021. Resultados: Un total de 9 artículos originales cumplieron los criterios de elegibilidad y fueron incluidos en la presente revisión. De los 9 estudios de intervención incluidos, 7 incluyeron un programa combinado de actividad física y nutrición, y 2 incluyeron únicamente un programa de ejercicio como estrategia de intervención. De los 9 incluidos, 8 mostraron reducción significativa de la esteatosis hepática. Conclusión: Los programas combinados de actividad física e intervención nutricional reducían significativamente la esteatosis hepática, mientras que los que estaban basados exclusivamente en ejercicio físico no inducían cambios significativos en el porcentaje de grasa hepática. Sin embargo, se precisan un mayor número de trabajos para extraer conclusiones más firmes Background: Childhood obesity is a problem of great magnitude. It is linked to multiple comorbidities, including non-alcoholic fatty liver disease (NADLF), and is currently one of the leading liver diseases in the overweight pediatric population. Purpose: this systematic review will try to evaluate whether physical activity programs are useful as a treatment line to reduce the percentage of liver fat in children with NAFLD. Methods: A systematic review of scientific evidence was carried out in PubMed and Web of Science. The search terms used for the search strategy were: child, nonalcoholic fatty liver disease (NAFLD), obesity, exercise, intervention. The search was performed from data inception to 17 of February 2021. Results: A total of 9 original articles met the eligibility criteria and were included in the present review. Of the 9 intervention studies included, 7 included a combined program of physical activity and nutrition, and 2 included only an exercise program as an intervention strategy. Of the 9 included, 8 showed a significant reduction in hepatic steatosis. Conclusion: The programs combining physical activity and nutritional interventions significantly reduced hepatic steatosis, while those that were based exclusively on physical exercise did not induce significant changes in the percentage of liver fat. However, a greater number of studies are required to draw stronger conclusions. Graduado o Graduada en Enfermería por la Universidad Pública de Navarra Erizaintzan Graduatua Nafarroako Unibertsitate Publikoan