In adults, there is a substantial body of evidence that physical inactivity or low cardiorespiratory fitness levels are strongly associated with the development of metabolic syndrome. Although this association has been studied extensively in adults, little is known regarding this association in adolescents. The aim of this study was to analyze the association between physical activity and cardiorespiratory fitness levels with metabolic syndrome in Brazilian adolescents.

/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.

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.

This trial aims to investigate the effects of the ActTeens physical activity program, on adolescents’ physical activity level, health-related fitness, cardiometabolic and mental health. The trial will aim to recruit ~140 adolescents (aged 13–14 years). Participants will be randomized into either intervention or control groups. The intervention will be guided by social cognitive theory and self-determination theory and implemented over one school term (24-weeks). The ActTeens Program will include: (1) structured physical activity sessions delivered within physical education, including movement-based games and dynamic stretching warm-ups; resistance training skill development; high-intensity training workouts; and cool-downs; (2) self-monitoring plus goal setting for physical activity by pedometer-smart wearable; and (3) healthy lifestyle guidance (social support) by WhatsApp® messages about healthy eating and regular physical activity for the intervention and parents groups. Study outcomes will be assessed at baseline, 24-weeks from baseline, and 12-months from baseline. Physical activity (accelerometer) is the primary outcome. Secondary outcomes include muscular and cardiorespiratory fitness, cardiometabolic profile, and mental health. A process evaluation will be conducted (i.e., recruitment, retention, attendance, and program satisfaction). This project will have the potential to address many questions and debates regarding the implementation of physical activity interventions in low-and- middle-income countries. Trial registration: ClinicalTrials.gov NCT05070377. Registered on 7 October 2021.