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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.

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El diagnóstico por bioimpedancia (BIA) y el ángulo de fase (AnF), como indicador, permiten monitorear el estado físico, de salud y nutricional en adultos mayores. El objetivo de este estudio fue establecer la relación entre la condición física y valores de fase angular por bioimpedancia en un grupo de adultos mayores sedentarios. Participaron voluntariamente 24 adultos mayores sedentarios (21 mujeres y 3 hombres). A cada participante se les midió bioimpedancia, fuerza de presión manual y test de 6 minutos del Senior Fitness Test (SFT). Posteriormente se analizaron los resultados, correlacionando el ángulo de fase (AnF) y condición física cardiorrespiratoria según sexo y el AnF con la fuerza de presión manual. El 71% presentó una media de AnF por debajo de la referencia (4,5º ± 0,4), específicamente, el 67% de los hombres y el 62% de las mujeres. La correlación entre AnF y capacidad física cardiorrespiratoria arrojó un valor de R2= 0,50; p<0,0001. La asociación entre AnF y fuerza de presión manual fue de R2=0,35; p=0,0023. Se encontró una relación significativa entre una prueba de condición física cardiorrespiratoria y AnF y entre la fuerza de presión manual y AnF. Es de importancia clínica incluir parámetros objetivos de valoración celular en adultos mayores como el AnF.

The diagnosis by bioimpedance (BIA) and the phase angle (PhA) are indicators, that allow monitoring of the physical health and nutritional status of older adults. The objective of this study was to establish the relationship between physical fitness and phase angle values by bioimpedance in a group of sedentary older adults. 24 elderly sedentary volunteers participated (21 women and 3 men). Each participant underwent bioimpedance, manual dynamometry, and the 6-minute Senior Fitness Test (SFT). Subsequently, the results were analyzed, making a correlation between PhA and cardiorespiratory physical condition, another between PhA and cardiorespiratory physical condition according to sex and finally an association between PhA and handgrip strength. R71% presented a PhA mean below the reference (4.5º ± 0.4), specifically 67% of men and 62% of women. The correlation between PhA and cardiorespiratory fitness showed a value of R2= 0.50; p<0.0001. The association between PhA and handgrip strength was R2=0.35; p=0.0023. A significant relationship was found between a cardiorespiratory fitness test and PhA and between handgrip strength and PhA. It is of clinical importance to include objective cellular assessment parameters in older adults such as PhA.

O diagnóstico por bioimpedância (BIA) e ângulo de fase (AnF), como indicador, permitem monitorar o estado físico, de saúde e nutricional de idosos. O objetivo deste estudo foi estabelecer a relação entre a condição física e os valores da fase angular por bioimpedância em um grupo de idosos sedentários. Participaram voluntariamente 24 idosos sedentários (21 mulheres e 3 homens). Cada participante foi medido bioimpedância, força de pressão manual e teste de 6 minutos do Senior Fitness Test (SFT). Posteriormente, os resultados foram analisados, correlacionando o ângulo de fase (AnF) e a condição física cardiorrespiratória de acordo com o sexo e o AnF com a força de pressão manual. 71% apresentaram média do LAn abaixo da referência (4,5º ± 0,4), sendo 67% dos homens e 62% das mulheres. A correlação entre o LAn e a aptidão cardiorrespiratória deu um valor de R2= 0,50; p<0,0001. A associação entre LAn e força de pressão manual foi R2=0,35; p=0,0023. Encontrou-se relação significativa entre teste de aptidão cardiorrespiratória e NF e entre força de pressão manual e NF. É de importância clínica incluir parâmetros objetivos de avaliação celular em adultos mais velhos, como AnF.

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In the pursuit of enhanced athletic prowess in different disciplines, athletes constantly look for strategies to increase their physical performance, encompassing technical skills and dietary components, which inevitably, in most cases, include the incorporation of sports supplements. In recent years, there has been an increase in the number of athletes using ergogenic aids. In this context, scientific evidence must play a prominent role in either endorsing or warning against the use of these products, ensuring the preservation of health while promoting the theoretically established positive benefits. In this vein, beetroot juice (BJ) stands out as a key supplement as an ergogenic aid to improve sports performance, given its demonstrated influence on both aerobic and anaerobic exercise. However, despite widespread global demand, there remains a lack of understanding regarding the potential synergistic effects of combining BJ with other supplements. Consequently, our study aims to determine whether the combination of BJ with another nutritional supplement can enhance its beneficial effects and, therefore, optimize physical performance in humans. A comprehensive literature search was conducted in two major databases-Web of Science and PubMed-from 1 January 2018 to 29 January 2023, using specific keywords. After the exclusion criteria, six articles were selected for analysis. Therefore, our study shows that the effectiveness of combining BJ with another supplement mainly depends on the duration of the chronic intervention, which is where the greatest benefits have been observed.

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Background: Improving health of children and adolescents is crucial for their overall development. Therefore, it is essential to explore factors that may influence their health at both the public health and school system levels. Objective: This study compares physical fitness components and waist-height-to-ratio (WHtR) in adolescents according to school uniforms, namely the traditional uniform (i.e., shirt and school necktie in boys and skirt and blouse in girls) and the sports uniform (i.e., polo shirts or t-shirts and sport or short trousers). Additionally, it seeks to investigate potential differences in these measures based on sex and school type (i.e., public, subsidized, and private). Methods: This cross-sectional study used data from the Chilean national learning outcome assessment system (SIMCE)-2014 and involved 8,030 adolescents. Cardiorespiratory fitness (CRF) and muscular fitness (MF) were measured. WHtR was assessed as a health cardiovascular indicator. Mixed models and ANCOVA were performed to compare uniform types, adjusting for multiple covariates. value of p and effect size (ES) was used to establish significant results. Results: Overall, sports uniforms (SU) were linked to higher CRF (p < 0.001) than the traditional uniform (TU). Boys from private schools wearing SU presented higher CRF (p = 0.016; ES = 0.37), and a positive trend was observed for MF (p = 0.645; ES = 0.21). In subsidized, a trend was found in CRF (p = 0.005; ES = 0.16). Girls wearing SU from private schools showed a positive trend in CRF (p = 0.167; ES = 0.28). Trends in WHtR were found in both sexes from private (p = 0.555; ES = 0.24; p = 0.444; ES = 0.25, respectively). Conclusion: Wearing SU seems a promissory alternative to promote healthy physical fitness and body composition at the educational level. However, the relationship between higher physical activity and CRF, MF, and lower WHtR due to SU must be verified. Finally, when deciding to implement this measure, special attention must be paid to boys from public schools and girls from all types of schools.

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OBJECTIVE: The objective of this study was to compare the levels of sedentary behaviour and physical activity in relation to sociodemographic variables of Chilean schoolchildren before and during the COVID-19 pandemic. METHODS: This retrospective study considered a non-random sample of 83 boys and 232 girls, and their respective parents, who attended public schools (n = 119) and private schools (n = 196) in Chile. A self-report instrument was applied that included sociodemographic variables, sedentary behaviour (SB), and physical activity (PA) in the second period of the pandemic in 2021. RESULTS: The main results show that pre-pandemic SB had significant differences when compared between sexes, except for television time. During the pandemic, there was no significant difference in television time or telephone time. There were no significant differences by sex before and during the pandemic. When comparing the SB scores, video game time in boys decreased (p < 0.001), as did video game time in girls (p < 0.001), and computer time in boys (p < 0.001) and girls (p < 0.001). Telephone time increased in boys (p < 0.001) and girls (p < 0.001), as did television time (p < 0.001). Likewise, PA increased in boys (Δ + 9.51min) and girls (Δ + 3.54 min) during the pandemic (p < 0.001). CONCLUSIONS: Both PA and SB underwent changes according to sex before and during the second period of the COVID-19 pandemic in Chilean schoolchildren.

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Background: There is still little understanding of the associations between physical fitness variables and bone health in children taking into account key confounders. Aim: The aim of this study was to analyze the associations between performance in tests of speed, agility, and musculoskeletal fitness (power of the upper and lower limbs) with bone mass of different regions in children, considering the adjustment to maturity-offset, lean percentage, and sex. Methods: Cross-sectional study design: the sample consisted of 160 children aged 6-11 years. The physical fitness variables tested were 1) speed, assessed with the running test at a maximum speed of 20 m; 2) agility, assessed through the 4×4-m square test; 3) lower limb power, assessed using the standing long jump test, and 4) upper limb power, assessed using the 2-kg medicine ball throw test. Areal bone mineral density (aBMD) was obtained from the analysis of body composition by dual-energy X-ray absorptiometry (DXA). Simple and multiple linear regression models were performed using the SPSS software. Results: In the crude regression analyses, the results indicated a linear relationship between all the physical fitness variables and aBMD in all body segments, but maturity-offset, sex, and lean mass percentage seemed to have an effect on these relationships. Except for the upper limb power, the other physical capacities (speed, agility, and lower limb power) were associated with aBMD in at least three body regions in the adjusted analyses. These associations occurred in the spine, hip, and leg regions, and the aBMD of the legs presented the best association magnitude (R 2). Conclusion: There is a significant association between speed, agility, and musculoskeletal fitness, specifically the lower limb power and aBMD. That is, the aBMD is a good indicator of the relationship between fitness and bone mass in children, but it is essential to consider specific fitness variables and skeletal regions.

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Background: Postexercise hypotension (PEH) is a common physiological phenomenon occurring immediately after endurance training (ET), resistance training (RT), and ET plus RT, also termed concurrent training (CT); however, there is little knowledge about the interindividual and magnitude response of PEH in morbidly obese patients. Aim: The aims of this study were (1) to investigate the effect of CT order (ET + RT vs. RT + ET) on the blood pressure responses; 2) characterize these responses in responders and nonresponders, and 3) identify potential baseline outcomes for predicting blood pressure decreases as responders. Methods: A quasi-experimental study developed in sedentary morbidly obese men and women (age 43.6 ± 11.3 years; body mass index [BMI] ≥40 kg/m2) was assigned to a CT group of ET plus RT (ET + RT; n = 19; BMI 47.8 ± 16.7) or RT plus ET order group (RT + ET; n = 17; BMI 43.0 ± 8.0). Subjects of both groups received eight exercise sessions over four weeks. Primary outcomes include systolic (SBP), diastolic (DBP), mean arterial pressure [MAP], heart rate at rest [HR], and pulse pressure [PP] measurements before and after 10 min post-exercise. Secondary outcomes were other anthropometric, body composition, metabolic, and physical fitness parameters. Using the delta ∆SBP reduction, quartile categorization (Q) in "high" (Rs: quartile 4), "moderate" (MRs: quartile 3), "low" (LRs: quartile 2), and "nonresponders" (NRs: quartile 1) was reported. Results: Significant pre-post changes were observed in ET + RT in session 2 for SBP (131.6 vs. 123.4 mmHg, p = 0.050) and session 4 (131.1 vs. 125.2 mmHg, p = 0.0002), while the RT + ET group showed significant reductions in session 4 (134.2 vs. 125.3 mmHg, p < 0.001). No significant differences were detected in the sum of the eight sessions for SBP (∑∆SBP) between ET + RT vs. RT + ET (-5.7 vs. -4.3 mmHg, p = 0.552). Interindividual analyses revealed significant differences among frequencies comparing Q1 "NRs" (n = 8; 22.2%), Q2 "LRs" (n = 8; 22.2%), Q3 "MRs" (n = 9; 25.0%), and Q4 "HRs" (n = 11; 30.5%), p < 0.0001. Quartile comparisons showed significant differences in SBP changes (p = 0.035). Linear regression analyses revealed significant association between ∑∆SBP with body fat % (ß -3.826, R 2 0.211 [21.1%], p = 0.031), skeletal muscle mass [ß -2.150, R 2 0.125 (12.5%), p = 0.023], fasting glucose [ß 1.273, R 2 0.078 (7.8%), p = 0.003], triglycerides [ß 0.210, R 2 0.014 (1.4%), p = 0.008], and the 6-min walking test [ß 0.183, R 2 0.038 (3.8%), p = 0.044]. Conclusion: The CT order of ET + RT and RT + ET promote a similar 'magnitude' in the postexercise hypotensive effects during the eight sessions of both CT orders in 4 weeks of training duration, revealing "nonresponders" and 'high' responders that can be predicted from body composition, metabolic, and physical fitness outcomes.

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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.

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(1) Background: The gut microbiota might play a part in affecting athletic performance and is of considerable importance to athletes. The aim of this study was to search the recent knowledge of the protagonist played by high-intensity and high-duration aerobic exercise on gut microbiota composition in athletes and how these effects could provide disadvantages in sports performance. (2) Methods: This systematic review follows the PRISMA guidelines. An exhaustive bibliographic search in Web of Science, PubMed, and Scopus was conducted considering the articles published in the last 5 years. The selected articles were categorized according to the type of study. The risk of bias was assessed using the Joanna Briggs Institute's Critical Appraisal Tool for Systematic Reviews. (3) Results: Thirteen studies had negative effects of aerobic exercise on intestinal microbiota such as an upsurge in I-FABP, intestinal distress, and changes in the gut microbiota, such as an increase in Prevotella, intestinal permeability and zonulin. In contrast, seven studies observed positive effects of endurance exercise, including an increase in the level of bacteria such as increased microbial diversity and increased intestinal metabolites. (4) Conclusions: A large part of the studies found reported adverse effects on the intestinal microbiota when performing endurance exercises. In studies carried out on athletes, more negative effects on the microbiota were found than in those carried out on non-athletic subjects.

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The main objective of the current study was to analyze how parents' sociodemographic characteristics, mode of commuting and physical activity (PA) act as indicators of active commuting to school (ACS) in their children and adolescents. A total of 684 paired parents (52.8% mothers) and their respective offspring (33.7% girls) were included. The participants self-reported their sociodemographic characteristics, mode of commuting, and PA. Logistic regression analyses were performed using a stepwise approach, including, as indicators, parental characteristics, mode of commuting and PA. The main outcome was child and adolescent ACS. The odds ratio (OR) and R2 of Nagelkerke were obtained for each step. Parental sociodemographic characteristics were greater indicators of child ACS than the parental mode of commuting and PA. In children, the greatest predictive variables of ACS explained 38% of the variance and were as follows: car availability (OR = 0.24), father's educational level (OR = 0.47), mother's educational level (OR = 1.95), mother's active commuting to work (OR = 4.52) and mother's salary/month (OR = 0.67). In adolescents, the greatest predictive variables of ACS explained 40% of the variance and were as follows: socioeconomic level (OR = 0.43) and father's active commuting (OR = 10.6). In conclusion, sociodemographic factors are better indicators of ACS than parents' physical activity and active commuting to work.