Study protocol and rationale of "the UP project": evaluating the effectiveness of active breaks on health indicators in desk-based workers.

Background: Excessive sedentary time has been negatively associated with several health outcomes, and physical activity alone does not seem to fully counteract these consequences. This panorama emphasizes the essential of sedentary time interruption programs. "The Up Project" seeks to assess the effectiveness of two interventions, one incorporating active breaks led by a professional and the other utilizing a computer application (self-led), of both equivalent duration and intensity. These interventions will be compared with a control group to evaluate their impact on physical activity levels, sedentary time, stress perception, occupational pain, and cardiometabolic risk factors among office workers. Methods: This quasi-experimental study includes 60 desk-based workers from universities and educational institutes in Valparaiso, Chile, assigned to three groups: (a) booster breaks led by professionals, (b) computer prompts that are unled, and (c) a control group. The intervention protocol for both experimental groups will last 12 weeks (only weekdays). The following measurements will be performed at baseline and post-intervention: cardiometabolic risk based on body composition (fat mass, fat-free mass, and bone mass evaluated by DXA), waist circumference, blood pressure, resting heart rate, and handgrip strength. Physical activity and sedentary time will be self-reported and device-based assessed using accelerometry. Questionnaires will be used to determine the perception of stress and occupational pain. Discussion: Governments worldwide are addressing health issues associated with sedentary behavior, particularly concerning individuals highly exposed to it, such as desk-based workers. Despite implementing certain strategies, there remains a noticeable gap in comprehensive research comparing diverse protocols. For instance, studies that contrast the outcomes of interventions led by professionals with those prompted by computers are scarce. This ongoing project is expected to contribute to evidence-based interventions targeting reduced perceived stress levels and enhancing desk-based employees' mental and physical well-being. The implications of these findings could have the capacity to lay the groundwork for future public health initiatives and government-funded programs.

Physical fitness mediates the inverse association between fatness indicators and academic achievement, despite the school vulnerability of adolescents-The Cogni-Action Project.

Objective: This study aims to determine the mediating role of physical fitness in the relationship between fatness indicators and academic achievement, exploring the influence of school vulnerability. Methods: A total of 1,296 Chilean adolescents (aged 10 to 14 years; 50% girls) participated in this study. The global fitness score (GFS) was obtained by adding the three main components of the ALPHA fitness test: cardiorespiratory fitness (CRF), muscular fitness (MF), and speed/agility fitness (SAF). CRF was evaluated through the 20 m shuttle run test; MF by upper and lower limb strength tests; and SAF by the 4 × 10 shuttle run test. BMIz and WHtR were evaluated as general (unspecific) and central (specific) fatness indicators. Academic achievement was established through grades in math, language, and science and their average scores. Multiple mediation analyses were performed according to two models, adjusted for sex, maturity, and schools (model 1), and in model 2, the school vulnerability index (SVI) was added. The SVI is an important proxy of socioeconomic status at the school level, and it was categorized as high-, mid-, or low-SVI. Mediation percentages were calculated, and confidence intervals (bootstrapping) were used to establish significant findings. Results: CRF, SAF, and GFS mediate the relationship between fatness indicators and academic achievement, both partially and totally (ranging from 12.7 to 59.2%). However, MF did not show any mediation effect. After controlling for SVI, CRF, and GFS, mediation changed from partial to total in the associations between math and science with WHtR. Although SAF contributed to GFS mediation, CRF seems to have the most significant mediation role for all academic achievements, regardless of SVI and the fat indicator studied. Conclusion: A higher level of general physical fitness, especially CRF, significantly mediates the detrimental influence of fatness on the academic achievement of schoolchildren. This study suggests that physical fitness plays a relevant role in academic and public health, considering the high prevalence and detrimental influence of obesity and school vulnerability in children and adolescents.

Which one? A comparative study of traditional and sports uniforms on academic achievement, cognitive performance, playtime, bullying, and discrimination in adolescents: The Cogni-Action Project.

Objective: The aim of this study was to compare academic achievement, cognitive performance, playtime, bullying, and discrimination in adolescents according to traditional uniforms (TUs) and sports uniforms (SUs) worn at school, while simultaneously exploring the influence of the school vulnerability index. Methods: A total of 988 Chilean adolescents (52.6% boys) aged 10-14 years participated in this cross-sectional study. Academic achievement was evaluated by the average grade in maths, language, and science grades, while cognitive performance was assessed through eight cognitive tasks. TUs affecting physical activity, playtime, bullying, and discrimination were queried. Mixed model analyses were performed. Results: No differences were observed in academic achievement (TU: 5.4 ± 0.1 vs. SU: 5.5 ± 0.2, p = 0.785) or in cognitive performance (TU: 99.6 ± 0.8 vs. SU: 98.9 ± 1.8, p= 0.754) according to the school uniformtype. Moreover, 64.1 % of participants declared that wearing TU affects their physical activity (traditional uniforms: + 8 min and sports uniforms: + 20 min), and those who believed so spent more time playing than those who answered negatively (14.5 min, p = 0.012). Finally, adolescents wearing SU displayed a lower feeling of bullying and discrimination; this finding depended mainly on the school's vulnerability. Conclusion: It is concluded that wearing TU does not show an educational advantage at an academic and cognitive level that justifies its obligation. In addition, it could be suggested that schools consider adolescents' opinions in adopting a more comfortable uniform, such as the SU. This feasible and low-cost measure would help to increase adolescents' physical activity during the school day, and, contrary to belief, it would not be related to increased feelings of bullying and discrimination.

Changes in Active Behaviours, Physical Activity, Sedentary Time, and Physical Fitness in Chilean Parents during the COVID-19 Pandemic: A Retrospective Study.

Strategies to reduce the spread of coronavirus disease 2019 (COVID-19) have caused different behavioural modifications in all populations. Therefore, this study aimed to determine changes in active commuting, moderate-to-vigorous physical activity (MVPA), physical fitness, and sedentary time during the COVID-19 pandemic in Chilean parents. Eighty-six fathers (41.30 ± 6.82 years) and 294 mothers (40.68 ± 6.92 years) of children from different schools from Valparaíso, Chile, participated. Inclusion criteria were adults with schoolchildren who were resident in Chile during the research period. Convenience sampling was used as a non-probabilistic sampling technique. Respondents completed a self-reported online survey about active commuting, MVPA, self-perceived physical fitness, and sedentary time July-September 2020 during the first pandemic period. Comparisons between before and during the pandemic were performed using t-tests and covariance analysis (ANCOVA), establishing a significance level at p < 0.05. Most participants stayed at home during the pandemic, whereas active and passive commuting significantly decreased in both fathers and mothers (p < 0.001). MVPA and physical fitness scores reduced considerably (p < 0.05), while sedentary time significantly increased (p < 0.05), independent of the sex of parents and children's school type. Differences by age groups and the number of children were more heterogeneous, as younger parents showed a larger decrease in MVPA (p < 0.05) and physical fitness score (p < 0.05). Additionally, parents with one child showed a larger decrease in sedentary time (p < 0.05) than those with two or more children. The COVID-19 pandemic significantly affected healthy behaviours. Hence, health policies should promote more strategies to mitigate the long-term health effects of the pandemic on Chilean parents.

Comparison of bioelectrical impedance parameters and body composition among street workout athletes according to training experience / Comparación de parámetros de impedancia bioeléctrica y composición corporal entre atletas de street workout según experiencia de entrenamiento

SUMMARY: Bioelectrical impedance analysis (BIA) is useful for determining bioelectrical parameters and body composition. In turn, differences have been reported when comparing these variables in athletes by training status. Nevertheless, there is no evidence of bioelectrical impedance parameters in Street Workout (SW) athletes. Thus, this study aimed to compare bioelectrical parameters and body composition through BIA between trained and untrained SW athletes. Twenty-two male SW athletes were classified as trained (n=6; 26.3 y [21.0-28.9]) and untrained (n=16; 21.8 y [20.5-24.7]) based on their SW experience. A bioelectrical impedanciometer was used to estimate bioelectrical parameters and body composition. There was no difference in body composition between trained and untrained SW athletes. Regarding impedance, trained athletes had lower values in the upper limbs (right arm: p=0.049; left arm: p=0.027) and trunk (p=0.004), while phase angle values were higher in the upper limbs (right arm: p=0.004; left arm: p=0.001), and trunk (p=0.006), as well as the mean phase angle (p=0.007), than untrained athletes. Bioelectrical impedance parameter differences found between SW training level groups suggest an improvement of tissue qualities, such as muscle, with SW practice. Future longitudinal studies should corroborate if SW training modifies these parameters.

RESUMEN: El análisis de impedancia bioeléctrica es útil para determinar parámetros bioeléctricos y de composición corporal. A su vez, se han reportado diferencias al comparar estas variables en atletas según su estado de entrenamiento. Sin embargo, no hay evidencia de parámetros de impedancia bioeléctrica en atletas de Street Workout (SW). Por tanto, este estudio tuvo como objetivo comparar los parámetros bioeléctricos y la composición corporal entre atletas de Street Workout entrenados y no entrenados. Veintidós atletas masculinos de Street Workout fueron clasificados como entrenados (n=6; 26.3 años [21.0-28.9]) y no entrenados (n=16; 21.8 años [20.5-24.7]) en función de su experiencia en Street Workout. Se utilizó un impedanciómetro bioeléctrico para estimar los parámetros bioeléctricos y la composición corporal. No hubo diferencias en la composición corporal entre los atletas de SW en- trenados y no entrenados. En cuanto a la impedancia, los atletas entrenados tenían valores más bajos en los miembros superiores (brazo derecho: p=0,049; brazo izquierdo: p=0,027) y en el tronco (p=0,004), mientras que los valores del ángulo de fase eran más altos en los miembros superiores (brazo derecho: p=0,004; brazo izquierdo: p=0,001), en el tronco (p=0,006), así como la media del ángulo de fase (p=0,007) que los atletas no entrenados. Las diferencias en los parámetros de impedancia bioeléctrica encontradas entre los grupos según el nivel de entrenamiento de SW sugieren una mejora de las cualidades de los tejidos, como el músculo, con la práctica de SW. Futuros estudios longitudinales deberían corroborar si el entrenamiento SW modifica estos parámetros.

Morphological differences of street workout athletes according to the training experience / Diferencias morfológicas en atletas de street workout según la experiencia de entrenamiento

SUMMARY: In several sports, morphological differences exist when comparing training status. However, these are less known in novel urban sports such as Street Workout (SW). This study compares the morphological characteristics between untrained (novice) and trained (experienced) SW athletes. Thirty-seven male Street workout practitioners from Viña del Mar (Chile) participated. Anthropometric, body composition, and somatotype data were assessed and compared according to the training experience. We found that trained SW athletes had a higher flexed and tensed arm perimeter (+4.4 %, p=0.038), lower hips perimeter (-4.8 %, p=0.041), narrower biiliocristal breadth (-3.2 %, p=0.035), lesser sum of 6 skinfolds (-40.8 %, p<0.001), and a lower endomorphic component (p<0.001) than untrained SW athletes. The proportionality analysis revealed that trained athletes had significantly higher upper body perimeters and lower skinfolds than untrained athletes. In addition, trained participants had higher percentages of the whole-body (+6.5 %, p<0.001) and upper limb muscle mass (+1.1 %; <0.001), and lower fat mass percentage (-7.9 %, p<0.001) and fat mass (-6.9 kg, p<0.001). In conclusion, similar to other sports, morphological differences exist in SW according to the training status, suggesting that morphology is associated with training experience. Further studies using DEXA should corroborate our findings and, in turn, determine the relevance of morphology in SW performance.

RESUMEN: En diversos deportes, existen diferencias morfológicas según la experiencia de entrenamiento. Sin embargo, en nuevos deportes urbanos como el Street Workout (SW) las diferencias son menos conocidas. El objetivo de este estudio es comparar las características morfológicas entre atletas de SW desentrenados (novatos) y entrenados (experimentados). Participaron treinta y siete hombres practicantes de SW en Viña del Mar (Chile). Se recolectaron datos antropométricos, de composición corporal y somatotipo, los cuales se compararon según la experiencia de entrenamiento. Encontramos que los atletas entrenados de SW tienen mayor perímetro de brazo flexionado y contraído (+4,4 %, p=0,038), menor perímetro de caderas (-4,8 %, p=0,041), diámetro biiliocrestideo (- 3,2 %, p=0,035), menor suma de 6 pliegues cutáneos (-40,8 %, p<0,001), y menor componente endomórfico (p<0,001), en comparación a los atletas desentrenados. El análisis de proporcionalidad reveló que los entrenados tienen perímetros de miembro superior más grandes y menores pliegues que los atletas desentrenados. Además, los entrenados tienen porcentajes mayores de masa muscular total (+6,5 %, p<0,001) y miembro superior (+1,1 %; <0,001), mientras que menor porcentaje de masa grasa (-7,9 %, p<0,001) y masa grasa (-6,9 kg, p<0,001). En conclusión, existen diferencias morfológicas en el SW según el nivel de entrenamiento, sugiriendo que la morfología está asociada a la experiencia de entrenamiento. Futuros estudios deberían corroborar nuestros hallazgos utilizando DEXA y, a la vez, determinar la relevancia de la morfología en el rendimiento en el SW.

Effects of a concurrent training protocol on body composition and phase angle in physically inactive young women: a quasi-experimental intervention study / Efectos de un protocolo de entrenamiento concurrente sobre la composición corporal y el ángulo de fase en mujeres jóvenes físicamente inactivas: un estudio de intervención cuasi-experimental

SUMMARY: To determine the effect of a concurrent training program on body composition and phase angle in young women. 38 women (19.26 ± 1.86 years) participated in the study, and were assigned according to convenience sampling into two groups: 11 into the control group (CG) and 27 into the intervention group (IG). The IG performed a 12-weeks concurrent training protocol. The frequency was five days a week, and the intensity was established in 40-60 % of a repetition maximum to strength exercise, and 40-65 % heart rate reserve to endurance exercise. Body composition and phase angle were evaluated by bioelectrical impedance before and after the intervention. The IG had a decrease in fat mass (pre = 24.66 ± 5.65 kg; post = 20.38 ± 4.20 kg; Cohen's d = .80; p< 0,001 [CI 95 % = 3.34,5.22]), and an increase in muscle mass (pre = 22.75 ± 3.23 kg; post: 23.50 ± 3.41 kg; Cohen's d = -0.86; p= <0,001[CI 95 % = -1.09,- 0.40]) and total phase angle (pre = 5.72º ±0.39; post: 6.24º ± 0.51; Cohen's d = -1.32; p=<0,001 [CI 95 % = -0.67,-0.36]), whereas the CG had not show significant variations in variables of body composition or total phase angle. The results suggest that a 12-weeks concurrent training program could modify positively the young women's body composition and phase angle. Hence, it is recommended using similar protocols to change variables related to young women's health.

RESUMEN: El objetivo fue determinar el efecto de un programa de entrenamiento concurrente sobre la composición corporal y el ángulo de fase en mujeres jóvenes. 38 mujeres (19.26 ± 1.86 años) participaron en el estudio, y fueron asignadas de acuerdo a un muestreo de conveniencia en dos grupos: 11 en el grupo control (CG) y 27 en el grupo de intervención (GI). El IG realizó un protocolo de entrenamiento concurrente de 12 semanas. La frecuencia fue de cinco días a la semana y la intensidad se estableció en 40-60 % una repetición máxima para el ejercicio de fuerza y 40-65 % de frecuencia cardíaca de reserva para ejercicio de resistencia. La composición corporal y el ángulo de fase se evaluaron mediante impedancia bioeléctrica antes y después de la intervención. El IG tuvo una disminución en la masa grasa (pre = 24.66 ± 5.65 kg; post = 20.38 ± 4.20 kg; d de Cohen = .80; p <0,001 [IC 95 % = 3.34,5.22]), y un aumento en la masa muscular (pre = 22,75 ± 3,23 kg; post: 23,50 ± 3,41 kg; d de Cohen = -0,86; p = <0,001 [IC 95 % = -1,09, -0,40]) y ángulo de fase total (pre = 5,72º ± 0,39; post: 6,24 º ± 0,51; d de Cohen = -1,32; p = <0,001 [IC 95 % = -0,67, -0,36]), mientras que el GC no mostró variaciones significativas en las variables de composición corporal o ángulo de fase total. Los resultados sugieren que un programa de entrenamiento concurrente de 12 semanas podría modificar positivamente la composición corporal y el ángulo de fase de mujeres jóvenes. Por lo tanto, se recomienda utilizar protocolos similares para mofificar variables relacionadas con la salud de mujeres jóvenes.

Composición corporal, parámetros bioeléctricos y fuerza de prensión manual en escaladores chilenos federados y recreativos / Body composition, bioelectrical parameters, and handgrip strength in federated and recreational Chilean climbers

RESUMEN: El objetivo del siguiente estudio fue determinar y comparar los valores de composición corporal, parámetros bioeléctricos y fuerza de prensión manual de escaladores chilenos federados y recreativos. Participaron voluntariamente 13 escaladores chilenos, de los cuales 4 eran federados (25,75 ± 2,87 años) y 9 recreativos (22,33 ± 1,41 años). La composición corporal se evaluó por medio de un impedanciómetro bioeléctrico octopolar multifrecuencia, mientras que la fuerza de prensión manual se determinó con un dinamómetro manual. Si bien no hubo diferencias en las variables de composición corporal entre ambos grupos, el ángulo de fase del tronco fue superior en los federados en comparación a los recreativos (p = 0,011 [95 % IC = 1,10; 5,20]). Respecto a la fuerza de prensión manual, la fuerza relativa fue superior para los federados (p = 0,025 [95 % IC = 0,10; 0,22]), mientras que la diferencia de la fuerza entre la mano dominante y no dominante fue mayor para los recreativos (p = 0,012 [95 % IC = 1,60; 10,05]). Este es uno de los primeros estudios que explora las diferencias entre escaladores chilenos federados y recreativos. Los resultados sugieren una diferenciación a nivel de ángulo de fase y fuerza de prensión manual, lo cual debería corroborarse con futuros estudios.

SUMMARY: This study aimed to determine and compare the body composition, bioelectric parameters, and handgrip strength in federated and recreational Chilean climbers. Thirteen Chilean climbers voluntarily participated, being 4 federated (25.75 ± 2.87 years) and 9 recreational (22.33 ± 1.41 years). Body composition was measured using a multifrequency octopolar bioelectrical impedance meter, while handgrip strength was determined with a dynamometer. Although there were no statistical differences in the body composition variables between groups, the trunk phase angle was statistically higher in the federated compared to the recreational climbers (p = 0,011 [95 % CI = 1,10; 5,20]). Regarding handgrip strength, the relative strength was higher for federated (p = 0,025 [95 % CI = 0,10; 0,22]), while the difference in strength between dominant and non-dominant hand was higher for recreational climbers (p = 0,012 [95 % CI = 1,60; 10,05]). This study is one of the first that explore the differences between federated and recreational Chilean climbers. These results suggest a differentiation at the level of phase angle and handgrip strength, which should be corroborated in future studies.

Características de composición corporal, ángulo de fase y agua corporal en paracaidistas chilenos de elite / Characteristics of body composition, phase angle and body water in elite Chilean skydivers

RESUMEN: Durante la práctica del paracaidismo, una deficiente composición corporal no sólo puede afectar el rendimiento deportivo, sino que, además, incrementa la probabilidad de sufrir una lesión o accidente grave. Conocer las características de sus componentes, podría ayudar a prevenirlas. El objetivo del estudio fue describir la composición corporal, ángulos de fase y agua corporal total en paracaidistas chilenos de alta competencia. Participaron del estudio 8 paracaidistas profesionales del Team Chile® (33,4 ± 4,9 años) con más de seis años de experiencia. La evaluación de las masas grasa, muscular, libre de grasa, magra y visceral, así como el ángulo de fase y el agua corporal total obtenida a través de impedancia bioeléctrica. Los deportistas presentaron un peso corporal de 76,7 ± 5,7 kg, estatura 1,72 ± 0,1 m e IMC 26,0 ± 1,9 kg/m2. La composición corporal promedio mostró un 20,6 ± 3,0 % de masa grasa, 44,9 ± 2,0 % de masa muscular y 79,4 ± 3,0 % de masa libre de grasa. El ángulo de fase promedio fue de 7,25 ± 0,33°. El agua corporal total de los participantes fue de 44,6 ± 3,2 1. Se concluye que los resultados obtenidos pueden ser utilizados por los profesionales de las ciencias del deporte como valores de referencia para el control de la composición corporal, fase angular y agua corporal en paracaidistas para optimizar el rendimiento deportivo y evitar lesiones.

SUMMARY: Unsuitable body composition in skydivers not only affect the sport performance but also could increase the probability of risk injury or severe accident; hence, to determine body composition characteristics could be helpful to prevent such events. This study aimed to describe body composition, phase angle, and total body water in highly trained Chilean skydivers. Eight Team Chile® professional skydivers (33.4 ± 4.9 years) with more than 6 years of experience participated in this study. Fat mass, muscle mass, fat-free mass, lean mass, visceral mass, phase angle, and total body water were measured by bioelectrical impedance. Skydivers had a bodyweight of 76.7±5.7 kg, a height of 1.72 ±0.1 m, and a body mass index of 26.0 ±1.9 kg/m2. Regarding body composition, they had a fat mass of 20.6 ±3.0 %, a muscle mass of 44.9 ±2.0 %, and a fat-free mass of 79.4 ±3.0 %. Phase angle and total body water were 7.25 ±0.3° and 344.6±3.2, respectively. The present findings could be useful to science sport professionals as reference values of body composition, phase angle, and total body water of highly trained skydivers to improve sports performance and avoid injuries.

Mediation Role of Physical Fitness and Its Components on the Association Between Distribution-Related Fat Indicators and Adolescents' Cognitive Performance: Exploring the Influence of School Vulnerability. The Cogni-Action Project.

Background: Physical fitness and fatness converge simultaneously modulating cognitive skills, which in turn, are associated with children and adolescents' socioeconomic background. However, both fitness components and fat mass localization are crucial for understanding its implication at the cognitive level. Objective: This study aimed to determine the mediation role of a global physical fitness score and its components on the association between different fatness indicators related to fat distribution and adolescents' cognitive performance, and simultaneously explore the influence of school vulnerability. Methods: In this study, 1,196 Chilean adolescents participated (aged 10-14; 50.7% boys). Cardiorespiratory fitness (CRF), muscular fitness (MF), and speed-agility fitness (SAF) were evaluated, and a global fitness score (GFS) was computed adjusted for age and sex (CRF + MF + SAF z-scores). Body mass index z-score (BMIz), sum-of-4-skinfolds (4SKF), and waist-to-height ratio (WHtR) were used as non-specific, peripheral, and central adiposity indicators, respectively. A global cognitive score was computed based on eight tasks, and the school vulnerability index (SVI) was registered as high, mid or low. A total of 24 mediation analyses were performed according to two models, adjusted for sex and peak high velocity (Model 1), and adding the school vulnerability index (SVI) in Model 2. The significance level was set at p < 0.05. Results: The fitness mediation role was different concerning the fatness indicators related to fat distribution analyzed. Even after controlling for SVI, CRF (22%), and SAF (29%), but not MF, mediated the association between BMIz and cognitive performance. Likewise, CRF, SAF and GFS, but not MF, mediated the association between WHtR and cognitive performance (38.6%, 31.9%, and 54.8%, respectively). No mediations were observed for 4SKF. Conclusion: The negative association between fatness and cognitive performance is mitigated by the level of adolescents' physical fitness, mainly CRF and SAF. This mediation role seems to be more consistent with a central fat indicator even in the presence of school vulnerability. Strategies promoting physical fitness would reduce the cognitive gap in children and adolescents related to obesity and school vulnerability.

Composición corporal y proporcionalidad en futbolistas chilenos: diferencias entre categorías juveniles y campeones profesionales / Body composition and proportionality in Chilean soccer players: sifferences between young and champion elite players

RESUMEN: El fútbol es el deporte más popular del mundo, por lo que las variables que benefician el rendimiento y el éxito deportivo generan un gran interés y ocupan un rol esencial en la preparación de futbolistas. Por lo tanto, el objetivo del presente estudio fue analizar la composición corporal y la proporcionalidad según la categoría y posición de juego. Se evaluaron a través de antropometría a 111 futbolistas de la selección chilena de fútbol en las categorías sub-15 (14,6±0,3 años), sub-17 (16,3±0,5 años), sub-20 (19,0±0,7 años) y elite (24,3±4,7 años); la significación se estableció en p<.05. En cuanto al peso, los porteros tuvieron el valor más alto para su posición; la categoría sub-20 obtuvo el valor más alto (83,7±3,8 kg). En cuanto a la estatura, los defensas centrales elite y la categoría sub-17 tuvieron los valores más altos (187,0±4,2 cm y 179,9±3,5 cm, respectivamente). Los porteros de todas las categorías tienen los mayores valores de IMC, siendo la categoría elite el más alto (25,1±1,3 kg/m2). Los delanteros/extremos sub-17 años tienen los valores más altos de masa muscular (60,5±8,0 %), mientras que los laterales sub-15 tienen los valores más bajos de masa grasa (9,6±0,7 %). Los jugadores de la selección chilena de fútbol tienen valores similares a los de otras investigaciones con jugadores de la misma edad y categoría; sin embargo, las categorías más jóvenes presentan diferencias significativas en las variables que proporcionan ventajas durante un partido con la categoría elite. Por lo tanto, se debe hacer énfasis en equiparar las condiciones físicas antes de promover a un jugador a categorías de mayor edad.

SUMMARY: Soccer is the most popular sport in the world. Thus, the variables that benefit performance and success have sparked great interest and occupy an essential role in the preparation of athletes. Therefore, the aim of the present study was to analyze the body composition and proportionality according to categories and playing position. 111 male soccer players of the Chilean national soccer team under-15 (14.6±0.3 years), under-17 (16.3±0.5 years), under-20 (19.0±0.7 years), and elite (24.3±4.7 years) categories were evaluated through anthropometry. Values of body composition and proportionality were recorded and organized by position and category; significance was established at p<.05. For weight, goalkeepers had the highest for their position; under-20 players, the highest for their category (83.7±3.8 kg). Regarding height, elite and under-17 central defenders had the highest values (187.0±4.2 cm and 179.9±3.5 cm, respectively). Goalkeepers in all categories have the highest BMI values; the highest were observed in elite (25.1±1.3 kg/m2). Under-17 forwards/extremes had the highest values in terms of muscle mass percentage (60.5±8.0 %), whereas under-15 fullbacks have the lowest values in terms of fat mass (9.6±0.7 %). The players of the Chilean national soccer team have similar values to other researches with players of the same age and category; however, the younger categories have significant differences in the variables that provide advantages during a game with the elite category. Therefore, emphasis should be placed on equating physical conditions before promoting a player to the older categories.

Effect of a Single Nutritional Intervention Previous to a Critical Period of Fat Gain in University Students with Overweight and Obesity: A Randomized Controlled Trial.

BACKGROUND: the present study aimed to investigate the effects of a single nutritional preventive session previous to a critical period linked to fat gain in university students with overweightness and obesity, emulating a nutritional session of a public health system. METHODS: In this single-blind randomized controlled trial, 23 students met all the criteria to be included (20.91 ± 2.52-year-old; 52.2% women) who were divided into two groups: intervention group (IG) and control group (CG). Fat mass (FM) by dual-energy X-ray absorptiometry (DXA), physical activity by accelerometry, feeding evaluation through three questionnaires, and a set of healthy lifestyle recommendations were evaluated before and after the national holidays (NH). RESULTS: Our findings showed that FM increased significantly in the CG, but not in the IG (CG = 428.1 g; IG = 321.9 g; Δ = 106.2 g; p = 0.654 [95% CI = -379.57, 591.92]). However, no differences were found during the NH between them (Hedges' g effect size = 0.19; p = 0.654). In addition, no statistical differences were observed between groups in feeding evaluations, the set of recommendations performed, and physical activity. CONCLUSION: a single preventive session before a critical period, using a similar counselling approach as used in the public health system, might not be enough to promote changes in eating and physical activity patterns and preventing fat gain in overweight/obese university students. Long-term interventions are a must.