Background: The aim of this study is to investigate the effects of a school-based high-intensity interval training (HIIT) program on quality of life and physical fitness in adolescents. Methods: The study included 60 male adolescents (16.2 ± 0.6 years), randomly assigned to one of two groups: the HIIT group (n = 30) and the control group (CG, n = 30). Participants completed the KIDSCREEN-27 questionnaire to evaluate quality of life and physical fitness tests, including vertical jump, repetitive strength, agility, and flexibility. The experimental program consisted of a 12-week intervention integrated into the warm-up phase of regular physical education (PE) classes. Each PE class lasted 45 min, with the HIIT regimen occupying 10 min of the warm-up phase. The HIIT sessions followed a Tabata-style structure, performed twice weekly. A two-way ANOVA with repeated measures assessed group and time interaction effects. Results: The results revealed changes in physical well-being following the HIIT intervention (p = 0.01) compared to the control group (p = 0.42). The results of the two-way ANOVA with repeated measures revealed interaction effects between group and time for the various fitness tests, countermovement jump (p = 0.04), 4 × 10 m agility test (p = 0.02), medicine ball throw test (p = 0.04), and sit-ups (30 s) (p = 0.01). Conclusions: This study highlights the effectiveness of school-based HIIT in significantly enhancing physical well-being and physical fitness among adolescents.

Body mass index (BMI) and body image (BI) are constructs worth examining in the context of physical activity (PA), and they are both related to quality of life (QoL). PA, BMI, and BI should all be considered as associated parameters, and their effect on QoL should be examined and understood. This study aimed to determine the moderating role of PA in the relationship of BMI and BI with QoL. The sample of examinees consisted of 500 respondents (307 women; aged 39 ± 6 years). A physical activity self-evaluation questionnaire (IPAQ-SF) was used to estimate PA; BI was evaluated by using the Body Image Dimensional Assessment (BIDA) questionnaire, while QoL was determined with the WHOQOL-BREF questionnaire. The results showed that vigorous PA moderates the relationship between BMI and social relationships in adults (Sig. = 0.000). Walking and vigorous PA affect the relationship between BMI and environmental health (Sig. = 0.017 and Sig. = 0.049, respectively). Both walking (Sig. = 0.035) and moderate PA (Sig. = 0.032) alternate the relationships between BI and social relationships. Walking (Sig. = 0.000) and vigorous PA (Sig. = 0.016) moderate the relationship between BI and environmental health. The influence of PA on the moderation of the relationship of BMI and BI with physical and psychological health in the working population was not statistically significant.

(1) Background: The aim of this study was to determine the effects of high-intensity interval training (HIIT) implemented in physical education classes on adolescents’ motivation for exercise. (2) Methods: This study involved 60 male adolescents (16.23 ± 0.6 years) recruited from a local high school who were randomly assigned to either the HIIT group or the control group (CG). The Exercise Motivation Inventory-2 (EMI-2) questionnaire was used to assess how participation in a HIIT program influenced the motivation to exercise among adolescents. The experimental program consisted of a 12-week HIIT program, integrated into the preparatory part of physical education classes. Sessions were held twice weekly, with each session lasting ~10 min. The HIIT group performed the Tabata protocol, which consisted of two 4 min sequences of eight different high-intensity exercises (burpees, split jumps, jumping jacks, push-ups, wall ball, crunches, frog jumps, and Russian twists), each lasting 20 s with 10 s rest intervals, separated by a 1 min recovery period. The control group conducted the traditional moderate-intensity warm-up exercises for the same total duration. After the warm-up protocols, both groups continued with the same physical education classes, which included a variety of instructional and moderate-intensity activities. (3) Results: A significant time × group interaction was observed for social recognition (p = 0.04; partial eta squared η2p = 0.079, medium effect), indicating that HIIT had a superior effect compared to CG. Affiliation also showed a significant improvement in the HIIT group (p = 0.02), while no significant changes were noted in the CG (p = 0.35). Similarly, competition significantly increased in the HIIT group (p = 0.02), whereas no significant differences were found in the CG (p = 0.74). For all other motivational factors, no significant effects of time or group factors were found (p > 0.05). (4) Conclusions: This study highlights the positive effects of school-based HIIT on male adolescents’ motivation, particularly in the area of social recognition.

This cross-sectional study examined parents’ attitudes, their support, and perceptions of school involvement in school sports using a newly developed Parental Attitudes and Support for School Sports and Perceptions of School Involvement Questionnaire (PASSIQ). The study also examined the association between parents' gender and children's sports participation concerning these attitudes and support levels. A total of 380 parents were included in the study, with 341 valid responses analyzed. Our findings indicate that higher levels of parental support are strongly associated with more positive attitudes toward school sports (p < 0.001). While perceptions of school support showed a marginally significant positive relationship (p = 0.083), extended participation in sports was generally associated with lower parental attitudes, potentially reflecting concerns about burnout or shifting perceptions over time. Notably, the interaction between parents' gender and children's sports participation revealed that for male parents, extended sports participation of their children significantly enhanced positive attitudes toward school sports (p = 0.004). These results highlight the importance of considering parental support and gender-specific responses when developing strategies to promote positive attitudes and support for school sports. The PASSIQ proved to be a reliable and valid tool for assessing these constructs, providing a foundation for future research and interventions to foster supportive environments for children's physical activity.

The aim of the study was to evaluate the factorial validity and reliability of the Serbian version of the Exercise Dependence Scale-Revised (EDS-R). The sample of participants consisted of 222 students from the Faculty of Sport and Physical Education, including 164 male participants and 58 female participants. All participants were over 18 years of age and reported engaging in exercise with a frequency ranging from 3 to 7 sessions per week. The main statistical analysis for this study was conducted using confirmatory factor analysis (CFA). The results indicate good overall reliability of the complete inventory (α > .82), while the reliability of individual subscales ranges from .56 to .84. The results of the confirmatory factor analysis demonstrate that the model nearly aligns with the established fit indices (χ² = 600.299; df = 168; p < 0.001; CFI = .891; NFI = .935; RMSEA = .093). The seven factors collectively explained 73.1% of the variance, with the first factor accounting for 16.4%, the second for 12.7%, the third for 11.1%, the fourth for 10.9%, the fifth for 8.3%, the sixth for 8.0%, and the seventh factor for 5.7% of the variance. The Serbian version of the Exercise Dependence Scale-Revised demonstrates solid psychometric properties, with acceptable fit indices that suggest its relevance for assessing exercise dependence within this population.