Background: Despite the positive effects of high-intensity training on weight management and health-related outcomes, it is postulated that high-intensity training may also induce oxidative stress, increasing hepatic damage. Aim: The aim of this study was to compare the effects of low versus high-intensity training on biomarkers related to non-alcoholic fatty liver disease (NAFLD) in adolescents with obesity. Methods: For this study 107 adolescents (15 ± 1 years) with obesity (BMI = 34.7 ± 4.1 kg/m²) were randomized into High-Intensity Training (HIT, n = 31), Low-Intensity Training (LIT, n = 31) or Control Group (CG, n = 45). Adolescents from HIT and LIT received nutritional, psychological and clinical counseling. Blood lipids, Castelli risk index, glucose, insulin and hepatic enzymes were measured at baseline and after 12 weeks. Results: Castelli risk index 1 was reduced in all groups ( p < 0.001) with moderate effect size ( d) for HIT ( d = 0.62) and LIT ( d = 0.66). Castelli risk index 2 also decreased ( p < 0.001 for all groups; HIT d = 0.65; LIT d = 0.79). High-density lipoprotein increased in all groups ( d = 0.25 and d = 0.18 in HIT and LIT), while alanine aminotransferase tended to reduce ( p = 0.062) in HIT ( d = 0.34) and LIT ( d = 0.73) and aspartate aminotransferase decreased ( p = 0.024) in both HIT ( d = 0.24) and LIT ( d = 0.45). There were no changes in glucose, insulin and insulin resistance. Conclusion: Both high and low-intensity training improved biomarkers related to NAFLD. Thus, high-intensity training can be a safe and effective alternative to prevent and treat NAFLD in adolescents with obesity.

Environmental temperature (T_e) is a main atmospheric parameter that may affect the physical and physiological demands of outdoor sports. Thus, this study aimed to examine the relationship of T_e with the physical and physiological demands of beach soccer match-play. Physical and physiological demands were collected from 60 male players during Portuguese elite beach soccer championship matches using a 10 Hz wearable global positioning system, heart rate, and the rate of perceived exertion (RPE). A bilateral counter-movement jump (CMJ) test assessed lower limb power performance before and immediately after the match. Fluid loss was determined by body mass weighing before and after the end of the match. T_e and wet-bulb globe temperature (WBGT) parameters were continuously recorded. The matches occurred across T_e ranging from ~20.0 °C to 43.0 °C. Physical demands, CMJ height, peak heart rate (HR_peak), mean heart rate (HR_mean), and RPE were not correlated with T_e. However, a significant correlation was found between fluid loss and T_e (r [95% CIs] = 0.67 [0.43–0.75]; p < 0.001). Beach soccer players maintained physical performance independent of T_e. The specific characteristics of the sport may have promoted adequate thermoregulatory adaptations, helping maintain the players’ physical performance, particularly in matches played under high T_e conditions. Elite beach soccer players maintained their physical performance independently of T_e and despite experiencing dehydration (a body mass decrease of more than 2%) when the T_e exceeded 35 °C.

Introduction: The prevalence of excess weight/obesity in adolescence has increased, and physical training may be effective in combating this scenario. Objective: To analyze the effect of different intensities of aerobic training on the body composition of obese adolescents undergoing multidisciplinary intervention. Methods: In this study, 107 pubertal (Tanner 3 and 4), obese (BMI=34.72±4.10 kg/m²) adolescents (14.85±1.44 years) were randomly assigned to three groups: high intensity training (HITG – ventilatory threshold I (VTI)); low intensity training (LITG – 20% below the VTI) and control group (CG), without intervention. The adolescents in the HITG and LITG underwent nutritional and psychological (1x/week) and clinical (1 x/month) follow-up and physical training (3x/week) for 12 weeks. Results: Reductions in fat mass (FM) and body fat percentage (BFP) (p< 0.001) and an increase in fat-free mass (FFM) (p<0.001) were observed in all groups. There was a reduction in BMI only in the experimental groups (p<0.001). Conclusion: The effects of multidisciplinary treatment on the body composition of obese adolescents occur independently of the intensity of aerobic physical training. Level of Evidence I; High quality randomized clinical studies with or without statistically significant difference, but with narrow confidence intervals.

Background: Understanding physical fitness (PF) trajectories during childhood is essential because they reflect developmental differences and indicate whether early fitness levels predict later outcomes. Clarifying PF tracking is important for school monitoring, early identification of at-risk children, and planning targeted interventions. Objective: To synthesize evidence on change of PF among children aged 5–12 years and, secondarily, to descriptively analyze stability (tracking) of PF components. Methods: Searches were conducted in PubMed, Scopus, PsycINFO, and Web of Science covering the last decade (to May 2025). Longitudinal studies assessing at least one PF component in children aged 5–12 years were included. Data extraction included study/sample characteristics, PF components, assessment tools, statistical methods, and outcomes. Methodological quality was assessed with the NIH Quality Assessment Tool for Observational Cohort Studies. Results: From 33,995 records, 18 studies met the criteria, with sample sizes from 147 to 1148 children and follow-up from 12 to 48 months. Most studies reported improvements in aerobic, musculoskeletal, and motor fitness, while flexibility showed mixed results. Boys generally outperformed girls in aerobic, motor, and musculoskeletal fitness, whereas girls performed better in flexibility. Stability coefficients, analyzed in a set of four studies, varied across PF components, and results should be interpreted with caution. Conclusions: PF generally improves during childhood, with sex-specific patterns and low-to-moderate stability, particularly for motor fitness.