/Objective: This study aimed to compare the effects of two combined training methods on health-related physical fitness components in adolescents. Seventy-six adolescents (16.1 ± 1.1 years, n = 44 female) were randomized into groups of moderate-intensity continuous training combined with resistance training (MICT + RT), high-intensity interval training combined with resistance training (HIIT + RT), or Control. The training sessions were performed twice weekly for 12 weeks. The health-related physical fitness components evaluated were: body composition, muscular and cardiorespiratory fitness. The intervention groups had a significant reduction in body fat percentage and improvement in abdominal repetitions and VO_2peak after 12 weeks of combined exercise program (p < 0.001). Intervention effects were found to significantly reduce body fat percentage for the MICT + RT and HIIT + RT groups compared to the control group (mean difference: −3.8; 95% CI: −6.2; −1 0.3; mean difference: −4.7; 95%CI: −7.1; −2.3, respectively). For muscle fitness, significant effects of the intervention were found in increasing the number of abdominal repetitions favoring the MICT + RT group compared to the control group (mean difference: 9.5; 95% CI: 4.4; 14.7) and HIIT + RT compared to the control group (mean difference: 14.1; 95% CI 9; 19.3). For cardiorespiratory fitness, significant effects of the intervention on improving VO_2peak were found in the experimental groups (MICT + RT vs Control group: mean difference: 4.4; 95% CI: 2.2; 6.6; and HIIT + RT vs. Control group: mean difference: 5.5, 95% CI: 3.3; 7.7). The results suggest that 12 weeks of training using MCIT + RT or HIIT + RT showed a similar effect for health-related physical fitness components in adolescents.

The clustering of metabolic syndrome risk factors is inversely related to the amount of physical activity. However, the question remains as to how much daily physical activity is enough to prevent the onset of metabolic disorders in adolescents? Therefore, the objectives of this study were to associate the metabolic risk score with the moderate to vigorous physical activity (MVPA) and to identify the amount of daily physical activity to prevent the onset of the metabolic risk factors in Brazilian adolescents.

Objective: To examine the associations between self-reported screen time and symptoms of stress, anxiety, and depression in adolescents.

To analyze the associations among autonomous motivation, self-efficacy, satisfaction of basic psychological needs, social support and perceived environment with physical activity practice of adolescents aged between 12 and 15 years; and to test autonomous motivations and self-efficacy as potential mediators of the associations between these environmental factors and physical activity practice. We evaluated 553 adolescents, that participated in the ActTeens Program. Physical activity was assessed using the Physical Activity Questionnaire for Adolescents. Autonomous motivation, self-efficacy, satisfaction of basic psychological needs, parents’ social support and perceived environment were assessed using specifics questionnaires. Linear regression models were used to test the associations. Parents’ support (β = 0.32), satisfaction of basic psychological needs of colleagues (β = 0.21) and teachers (β = 0.12), and perceived environment (β = 0.10) had significant associations with physical activity (p < 0.05). The direct effect value was reduced when autonomous motivation was added as a mediator of the association between parents’ support and physical activity (β = 0.24), with a 25% mediated effect. Autonomous motivation was mediator of the relationship between basic psychological needs of colleagues (β = 0.13; EM = 38%), teachers (β = 0.02; EM = 83%), and perceived environment (β = 0.03; EM = 70%) with physical activity. Self-efficacy was not associated with physical activity and autonomous motivation was an important mediator of adolescents’ physical activity.

This study examined relationships between health-related physical fitness indicators and clustered cardiometabolic risk factors in adolescents between 2014 and 2017. The sample consisted of 93 students (60% girls), with complete data sets in both 2014 and 2017. The physical fitness components evaluated were: flexibility (sit and reach), muscular fitness (curl-up and push-up), cardiorespiratory fitness (progressive aerobic cardiovascular endurance run), and body fat (BMI). The cardiometabolic risk factors were: waist circumference, blood pressure, high-density lipoprotein cholesterol (HDL-C), triglycerides and fasting blood glucose. Z-scores were calculated for each risk factor, with the sum of risk factor z-scores values used to represent clustered cardiometabolic risk. The results of cross-sectional analysis indicated that muscle fitness (curl-up: β = −0.37, p < 0.001; push-up: β = −0.38, p < 0.005) and cardiorespiratory fitness (β = −0.56, p < 0.001) were inversely associated with clustered cardiometabolic risk, with BMI positively associated (β = 0.58, p < 0.001). In the longitudinal analysis, cardiorespiratory fitness (β = −0.33; p < 0.005) and body fat (β = 0.46, p < 0.001) demonstrated a significant association with clustered cardiometabolic risk. However, no significant associations between the health-related physical fitness and clustered cardiometabolic risk were observed after adjustment for baseline values. Our cross-sectional findings highlight the importance of health-related physical fitness indicators to adolescents. In regarding the longitudinal analysis, further studies are needed in order to clarify the influence of physical fitness in the adolescence and cardiometabolic risk later in life.

To test the effects of a physical activity intervention program on symptoms of mental disorders among adolescents. This study is a 12-week cluster randomized controlled trial. The sample consisted of 306 adolescents (45,8% male, age: 13,6 [0,72] years; 54.2% female, age: 13.5 [0.69] years), randomized into an intervention group (N = 165) and a control group (N = 141). The physical activity program involved sessions including muscle strengthening and cardiorespiratory exercises and lifestyle guidance. The mental health indicators analyzed were: anxiety, depression, sleep, and psychological well-being. Intervention effects were analyzed by generalized estimating equations. After 12 weeks, no significant improvements were observed in the intervention group for sleep; anxiety; depression, and psychological well-being. In the subgroup analysis, significant group×time interactions were observed for adolescents who were classified with moderate symptoms of depression (mean difference: -0.97, p = 0.002) and anxiety (mean difference: -3.03, p = 0.01) with favorable effects for intervention group. After the 12-week intervention period, it can be concluded that 12 weeks of school-based physical activity intervention significantly reduced symptoms of anxiety and depression in adolescents with moderate/severe symptoms. Furthermore, the intervention contributed to the maintenance of psychological well-being, since the control group showed a significant reduction in this mental health indicator.