Background/Objectives: The aim of this research was to determine the differences in physical fitness according to the level of physical activity (PA) during physical education classes in 10-year-old school children. Methods: The research included 315 primary school children (age 10 ± 1.3 years), divided into three groups by level of PA: low, moderate and high. A Eurofit test battery was used to evaluate the physical fitness of children. Physical activity (volume (number of steps) and intensity) was measured using a Coach Gear pedometer and a Suunto Memory Belt heart rate monitor. Results: Presented results indicate that there are significant differences between groups of children of both genders in relation to the level of PA. Group of boys with low PA showed lower values in sit and reach (p = 0.01), standing long jump (p = 0.02), bent arm hang (p = 0.04) and polygon backwards (p = 0.01) compared to the remaining two groups. Girls with low physical activity showed significant differences in sit and reach (p = 0.01) and bent arm hang (p = 0.01) compared to the other two groups, while in hand tapping, the high PA group showed better results compared to the other two groups (p = 0.03). Conclusions: The results reported in this research support the significant effects of PA level on physical fitness in school children. Less active children generally showed poorer physical fitness in both genders.

Physical education, from the earliest age in preschool institutions, and then through primary and secondary schools, is the only place where children can, in the right way, acquire the knowledge on sports, skills, behaviour, necessary in order to get the continuity of physical activities in the adulthood. Primary school is a period when the students experience great changes in the overall developing status. Therefore, Physical Education has a fundamental role in the development of psychosomatic characteristics of children. While planning lessons of Physical Education, there is a special emphasis on the development of motor skills. The goal of this research refers to the establishing of the existing differences in the motor space of primary school children in relation to age. The sample consisted of 231 examinees who attended 3rd, 4th, 5th and 6th grade (age 11 ± 1.6 years), out of which there were (N = 109; TV = 147.6 ± 7; TM = 39.6 ± 7.1) boys, and (N = 122; TV = 148.3 ± 5.9; TM = 40 ± 5.3) girls. All examinees were the students from the territory of Zlatibor region and with the signed permission for performing testing by both parents. Motor skills have been estimated within school Physical Education, all with the purpose of getting more realistic picture on the motor skills of children. The presented results point to the existing differences between the groups of examinees of both genders on a general level, as well as the individual differences within the motor space. These differences are more noticeable with boys (F = 5.92; P = .00) than with girls (F = 4.79; P = .00). Statistically greater differences with boys have been noted in the following variables: "Hand tapping", "Hand clapping", "Throwing basketball ball", "the 30 m running flying start", "Pull-ups", and "Torso lift-ups". With girls, statistically significant difference have been notes in the following variables: "Throwing basketball ball", "the 30 m running flying start" and "Torso lift-ups". The value of this work is reflected in the fact that, during testing, a great number of tests were used for estimation of the examinees' motor space, all with the purpose of getting more complete picture on the existence of differences among the groups, categorised by gender and age. The importance of testing and perception of differences in motor skills and their monitoring presents one of the important activities during PE classes, all with the purpose of the adequate lesson programming, but also monitoring the motor development.

Background: This study aimed to investigate the differences in motivation and physical self-concept among pupils based on their level of physical activity during physical education classes. Methods: The research encompassed 398 pupils (aged 10 ± 0.3 years), including 211 boys and 187 girls, divided into three groups according to their level of physical activity during class (Group A—low; Group B—medium; Group C—high). The modified Self-Regulation Questionnaire was used to evaluate pupils’ motivational orientations, while the corresponding subscales of the Self-Perception Profile for Children (SPPC) were employed to measure physical self-concept. Pupils’ physical activity (measured in steps and intensity) during physical education classes was assessed using CoachGear pedometers and Suunto Memory Belt heart rate monitors. Results: The findings revealed significant differences between the groups of pupils of both genders concerning their physical activity levels during early school years. Notably, these differences were more pronounced in boys than in girls. Additionally, it was observed that less active pupils generally exhibited lower levels of motivation as well as lower physical self-concept scores. Conclusion: Pupils with higher levels of physical activity during physical education classes demonstrated greater motivation and a more positive physical self-concept, highlighting the crucial role of engagement in fostering both psychological and physical development. These findings underscore the need for well-structured and engaging physical education programs that support active participation and enhance pupils’ overall well-being.

Background: This study examined the effects of high-intensity interval training with change of direction (HIITcod) and small-sided games (SSGs) on components of physical fitness in school-aged children. The aim was to provide practical insights for optimizing exercise interventions in constrained indoor environments. Methods: A randomized controlled trial was conducted during regular physical education (PE) classes in a school’s indoor sports hall. Fifty healthy boys (mean ± SD = 12.6 ± 0.6 years) were randomly assigned to a HIITcod group (n = 25) or an SSG group (n = 25). The intervention lasted eight weeks and consisted of structured training sessions designed to progressively increase intensity and training load in a child-friendly and safe environment. Individual maximal heart rate (HRmax) was determined using the 20 m shuttle run test prior to the intervention. Heart rate monitors were worn throughout all sessions to ensure exercise intensity consistently exceeded 75% of HRmax, with real-time monitoring used to adjust effort when necessary. Physical fitness outcomes, including the shuttle run test (SRT), handgrip strength (HG), 20 m sprint, standing broad jump (SBJ), Illinois agility test, and T-test, were assessed pre- and post-intervention. Results: Both groups demonstrated significant improvements over time in the SRT, SBJ, Illinois agility test, and T-test (p < 0.05). No significant group × time interactions were detected (all p > 0.05). Handgrip strength increased significantly in the HIITcod group (35.03 ± 7.19 kg to 36.80 ± 6.68 kg, p = 0.001, d = 0.25) and showed a non-significant trend in the SSG group (38.28 ± 9.09 kg to 39.23 ± 9.12 kg, p = 0.056). No significant changes were observed in 20 m sprint performance. Conclusions: Based on the study results, both HIITcod and SSGs were associated with improvements in multiple components of physical fitness in school-aged boys. These findings suggest that both training modalities may be viable options for implementation during physical education classes, particularly in limited indoor settings. The observed positive changes in fitness could indicate their potential to positively impact children’s fitness in a structured and engaging manner.