7 Mime Mokhtar, Hamzaoui Hakim, Benchehida Abdelkader, Cherara Lalia. Effect of 8 weeks CrossFit exercises on high school students during a physical fitness program. Quality in Sport. 2022;8(1):7-20. eISSN 2450-3118. DOI http://dx.doi.org/10.12775/QS.2022.08.01.001 https://apcz.umk.pl/QS/article/view/36230 The journal has had 20 points in Ministry of Education and Science of Poland parametric evaluation. Annex to the announcement of the Minister of Education and Science of December 21, 2021. No. 32582. Has a Journal's Unique Identifier: 201398. Scientific disciplines assigned: Economics and finance (Field of social sciences); Management and Quality Sciences (Field of social sciences). Punkty Ministerialne z 2019 - aktualny rok 20 punktów. Załącznik do komunikatu Ministra Edukacji i Nauki z dnia 21 grudnia 2021 r. Lp. 32582. Posiada Unikatowy Identyfikator Czasopisma: 201398. Przypisane dyscypliny naukowe: Ekonomia i finanse (Dziedzina nauk społecznych); Nauki o zarządzaniu i jakości (Dziedzina nauk społecznych). © The Authors 2022; This article is published with open access at Licensee Open Journal Systems of Nicolaus Copernicus University in Torun, Poland Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author (s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non commercial license Share alike. (http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. The authors declare that there is no conflict of interests regarding the publication of this paper. Received: 27.11.2021. Revised: 20.10.2022. Accepted: 04.11.2022. Effect of 8 weeks CrossFit exercises on high school students during a physical fitness program Mime Mokhtar1, Hamzaoui Hakim1, Benchehida Abdelkader1, Cherara Lalia1 1 - Laboratory of Optimizing Research Programmes on Physical and Sports Activities, Institute of Physical Education and Sport, University of Mostaganem, Mostaganem, Algeria Abstract Purpose: The aim of this study was to assess the effectiveness of a CrossFit exercises over a period of 8 weeks in a group of high school students during their physical education sessions at the school. and to mitigate the deficits in fitness caused by COVID-19 prevention measures. Material and methods: 94 students subject aged (16– 17) years were randomly allocated into an included 46 students (2nd level :12 men 11 women; 3rd level : 12 men 11 women) and 1 control group included 48 students (2nd level :13 men 11 women; 3rd level : 13 men 12 women Experimental group (EG) that performed the 8 weeks CrossFit exercises and control group (CG). Physical fitness tests were done : lifting straight legs in height (number times); running on the spot with an intensity of 70% of the maximum to severe fatigue (c); "Shuttle" run 4 × 9 m (with); 60 m run (s) and cross twine (cm).Results: there are a considering changes, development of the maximum dynamic force endurance, speed abilities, flexibility and mobility in the hip joints of the main groups, In the age aspect, there is mainly the improvement in results with age, both in the main and control groups (p>0,05). Conclusion: the study achieved a significant improvement in the physical condition of the students, also allows to talk about the effectiveness of training, built on the basis of a motivated choice of the target CrossFit high school program. Keywords: physical fitness, CrossFit, high school, program. http://dx.doi.org/10.12775/QS.2022.08.01.001 https://apcz.umk.pl/QS/article/view/36230 8 1. Introduction To date, there is a problem of decline level of physical fitness, and as a consequence of health student youth. A number of leading experts (Harold W. Kohl et al. 2013; Kaur et al. 2020; Mameshina 2019; Masliak et Mameshina 2018a; Petrova et Bala 2020) note that according to statistics, almost 60% high school children have health problems and low levels of physical fitness. The main reasons for this problem are the features of education in the modern school(Krivoruchko et al. 2018a), the growth of educational information, the intensification of material, modernization and complication of educational programs(Varea, Riccetti, et Siracusa 2021). All this leads to an increase in mental load and a decrease in motor activity of children (Batorova et Sørensen 2019). Exercise is an effective means of compensating for the deficit of motor activity of the modern student (Cacioppo et al. 2021; Kolokoltsev, Iermakov, et Jagiello 2018; Mohammed et al. 2018; Varea et al. 2021; Voloshina et al. 2018). However, according to the results of a number of authors (Adel, Alia, et Mohammed 2020; Andrieieva et al. 2020; Bodnar et Andres 2016; Krivoruchko et al. 2018b; Palichuk et al. 2018; Prysiazhniuk et al. 2021; Sibley 2012), currently operating lessons are ineffective, monotonous, do not sufficiently stimulate students to physical culture and sports activities. Therefore, this problem requires the search for new interesting forms, innovative means, methods and principles of system improvement physical education, increasing the volume and diversification of types of motor activity (Adel et al. 2019; Cacioppo et al. 2021; Petrova et Bala 2020; PRICOP et al. s. d.; Voloshina et al. 2018). A number of scientists pay considerable attention to the issue optimization of the content of physical education lessons (Masliak et al. 2019; Masliak et Mameshina 2018b; Petrova 2021; Varea et al. 2021; Voloshina et al. 2018). Numerous studies have identified the positive effects of various types of motor activities for the physical fitness of students of different ages(Belkadi et al. 2015; Fedewa et Ahn 2011; Mokhtar et al. 2019; Seefeldt, Malina, et Clark 2002; Sibley et Etnier 2003; Strong et al. 2005). Thus, Vlasova (2017) found an improvement in the level of physical fitness of junior schoolchildren under the influence of fitball-aerobics; Krivoruchko (2018) established a positive dynamics of indicators of the level of speed development under the influence cheerleading exercises for schoolchildren of 5th-6th grades;(Granacher et al. 2011; Hsieh et al. 2017; Root et al. 2019; Yacine et al. 2020) found that under the influence of athletic gymnastics classes is reflected the tendency to improve the data of physical fitness in high school students. It should be noted, that the analysis of literature sources showed the absence of scientific works that would raise the question of the impact of CrossFit exercises to the level of physical fitness of high school students. Thus, the above indicates relevance and feasibility of the study. The purpose of the study is to determine the degree of change in the level of physical fitness of high school students the influence of CrossFit exercises. Connection of work with scientific programs, plans, topics. 9 2. Materials and Methods 2.1. Participants This is the first paragraph of the section including a run-on quotation which is a short quotation (up to 50 words) embedded into the body text. Run-on quotations are opened and ended with quotation marks e.g. Knowledge management is defined as “the effective learning processes associated with exploration, exploitation and sharing of human knowledge (tacit and explicit) that use appropriate technology and cultural environments to enhance an organisation’s intellectual capital and performance” (Jashapara, 2004, p. 12). The study was conducted on the basis of general physical education and sports program during 2020–2021. study comprised 94 subjects’ students aged (16– 17) years, of which experimental groups included 46 students (2nd level :12 men 11 women; 3rd level : 12 men 11 women) and 1 control group included 48 students (2nd level :13 men 11 women; 3rd level : 13 men 12 women. All students who participated in the study were practically healthy and under the supervision of school doctor. During the study, students in the control groups were based only on the general physical education and sports program for high school students in secondary school(Beboucha et al. 2021), and the educational process on physical education of experimental groups was designed with a variable module developed by us "CrossFit school challenge". The CrossFit classes were held twice per week according to the school schedule. To the content of which included theoretical information, special physical training push (elements of gymnastics, athletics and weightlifting, general developmental exercises) and special training exercise(Lalia et al. 2019) (specially selected CrossFit exercises: "Burpee", "Box Jump", "Farmer's Walk", "Good morning", (Bear crawl”, “Floor wipers”, “Burpee bench jump”, etc.)(Petrova 2021). At the end of studying the module "CrossFit" students performed a set of exercises in the same conditions, which was formed of special and technical elements of CrossFit, for a short time period and with the specified number of rounds(Granacher et al. 2011). The age, gender and anthropometric and physiological assessments took part in evaluation of high school students. Load and level of difficulty was increased gradually taking into account the individual abilities of student’s performance. Also exercises CrossFit was included in the preparatory part of the lesson of others variable modules in the system of organized breaks and were given in the form of work out exercise(Cacioppo et al. 2021; Petrova et Bala 2020; Prysiazhniuk et al. 2021). To determine the level of development of physical qualities, tests were used by high school students, namely, lifting straight legs in height (number times); running on the spot with an intensity of 70% of the maximum to severe fatigue (c); "Shuttle" run 4 × 9 m (with); 60 m run (s) and Transverse twine (cm)(Long 2017; Maulder 2018; Reiman et Manske 2009). The research was conducted in accordance with the initiative of the research work "Improvement the process of physical education in educational institutions of various profiles "for 2020-2022 (state registration number IEPS2020/0036)(Belkadi et al. 2019) and in accordance with the Helsinki Declaration (World Medical Association 2013) 2.2. Statistical analysis: Statistical analysis was performed using the using SPSS software (version 22) and Significance levels were set at p ≤ 0.05. Shapiro- Wilk test was used to evaluate normal distribution of the conformity of continuous variables. The reliability of differences in 10 the results of the mean values in two unrelated samples was determined using Student's t-test. 3. Result the study indicates the lack of significant differences between the indicators studied. In terms of age, most of the improvements have been identified. results with age, both in 2nd and 3rd level secondary school students compared with control groups. Comparing the results by gender, it was founded that reliable prevalence of these young men over the indicators of women (p <0.05– 0.001), with the exception of the transverse twine test, where the opposite trend, the performance of women is better than the data men, and these changes are mostly significant (p <0.05– 0.01). After the introduction of experimental methods, a significant improvement was found in all subject’s indicators, both boys and women of the main groups (Table 1), and these differences are statistically significant (p <0,05– 0.001). there is an increase in results that reflect the level development of strength in men of the 2nd level, amounted to (23.7%), 3rd level (22.9%); women, respectively (54.6%) and (42.7%); time motion in men of the 2nd level is (8.3%), 3rd level ( 7.5%); women have (24.9% and 20.7%), respectively; agility: boys of the 2nd level is (4.1%), the 3rd level ( 7.8%); women have (4.2%) and (5.7%), respectively; high-speed abilities - in young men of the 2nd level is (3.7%), 3rd level (3.5%); women (9.7%) and (3.6%), respectively; flexibility young men of the 2nd level makes 10,6%, 3rd level - 11.3%; women have 23.7% and 14.6%, respectively Table 1. Indicators of the level of physical fitness of students of the main groups before and after the application. class level Sex Experimental group t P N Post test Pres test Mean SD Mean SD Lifting straight legs in the axis ( number of times ) 2nd level Men 12 15,35 1,89 17,98 2,05 4,27 <0,001 women 11 8,23 1,54 11,36 2,97 6,69 <0,001 3rd level Men 12 15,9 2,68 18,72 1,83 2,13 > 0,05 women 11 9,97 0,76 13,34 1,23 8,01 <0,001 Running on place with an intensity of 70% from maximum to severe fatigue ( s ) 2nd level Men 12 117,37 3,09 125,2 1 4,85 <0,001 women 11 32,14 2,38 42,9 1,21 9,04 <0,001 3rd level Men 12 129,16 1,91 139,59 0,66 5,13 <0,001 women 11 34,09 1,65 39,57 2,75 4,79 <0,001 " Shuttle " run 2nd level Men 12 9,91 0,19 9,6 0,2 3,53 <0,01 women 11 11,76 0,74 10,03 0,25 3,91 <0,01 3rd level Men 12 9,81 0,16 9,33 0,15 5,41 <0,001 women 11 11,14 0,17 9,62 1,07 3,59 <0,01 60 m ( s ) running 2nd level Men 12 10,12 0,1 9,73 0,11 4,29 <0,01 women 11 12,18 0,26 10,12 0,21 8,52 <0,001 11 3rd level Men 12 10,09 0,12 8,9 0,1 3,27 <0,05 women 11 12,3 0,26 11,07 0,97 4,31 <0,001 Transverse twine ( cm ) 2nd level Men 12 28,31 1,97 26,53 2,48 2,14 <0,05 women 11 21,39 2,73 17,84 1,89 5,53 <0,001 3rd level Men 12 30,47 3,37 27,9 3,14 3,29 <0,001 women 11 21,32 2,81 16,59 2,54 4,18 <0,05 Analyzing the studied indicators in age and gender aspects obtained after application of the CrossFit exercises.it was found that high school students pre-test, mainly the trend of distinctions remained variable, compared to the post test. Investigating the performance of students in the control groups test, it was found that they are also somewhat improved, however, these changes are not significant and unreliable (p> 0.05) (table 2). Thus, the increase in results varied from 0.6% to 8.7%. It should be noted that by age and gender no revealed changes compared to the post-test. When comparing repeated data of experimental and control groups (Table 2) established a significant pre- evaluation of the results of the main groups over the control. It should be noted that significant differences in tow groups on the indicators of lifting straight legs in height 3rd level class students (p <0.05); running on the spot with intensive 70% of maximum to severe fatigue high school students of 2nd -3rd level (p <0.05; 0.001); "Shuttle" running 4 × 9 m boys of the 3rd level class (p <0.001); 60-meter run, the 2nd level students (p <0.01) and Transverse twine girls 3rd level class (p <0.05). Determining the level of physical fitness of student’s senior school age after implementation in the process physical education of the variable module "CrossFit", revealed that against the background of significant and significant improvement results, it increased by 1 point and became equal score of 4 points, indicating an "above average" level. Thus, indicators of the level of development of strength, endurance, agility and flexibility on average correspond to the estimate - 4 points ("above average"), speed abilities - 3 points ("average" level). It should be noted that in the study in the control groups, the indicators remained un- variables, i.e., changes on the rating scale are not observed. Thus, the results of the study indicate positive dynamics of indicators of physical fitness those students aged 16-17 of the main groups under the influence of exercises CrossFit. Table 2. Comparison of indicators of physical fitness of students experimental and control groups after the experiment Classes Sex Groups t p Experimental Control N mean±SD N mean±SD Lifting straight legs in the axis ( number of times ) 2nd level Men 12 17,98±2,05 13 14.35 ± 1.65 1,57 > 0.05 Women 11 11,36±2,97 11 8,84 ± 1,58 1,38 > 0.05 3rd level Men 12 18,72±1,83 13 14.82 ± 1.46 2,64 <0.05 Women 11 13,34±1,23 12 11.49 ± 1.65 2,85 <0.05 Running on place with an intensity of 70% from maximum to severe fatigue ( s ) 2nd level Men 12 123,5±1,03 13 119.94 ± 1.86 2,06 <0.05 Women 11 43,21±1,29 11 35.25 ± 1.87 5,48 <0.001 12 3rd level Men 12 138,6±0,79 13 133.24 ± 2.43 4,95 <0.001 Women 11 40,48±2,73 12 38.71 ± 1.60 2,65 <0.05 " Shuttle " run 4 × 9 2nd level Men 12 9,08±0,34 13 10.05 ± 1.65 1,85 > 0.05 Women 11 11,08±0,94 11 12.83 ± 0.98 1,36 > 0.05 3rd level Men 12 9,07±0,64 13 9.51 ± 0.72 5,64 <0.001 Women 11 9,76±4,48 12 11.75 ± 1.34 1,59 > 0.05 60 m (s) running 2nd level Men 12 8,94±0,64 13 9.48 ± 0.42 1,22 > 0.05 Women 11 10,28±0,34 11 11.25 ± 0.75 2,84 <0.01 3rd level Men 12 8,94±0,41 13 9.64 ± 1,35 1,28 > 0.05 Women 11 10,06±0,86 12 12.16 ± 0.64 1,65 > 0.05 Transverse twine (cm) 2nd level Men 12 27,52±3,06 13 28.95 ± 3.43 0,65 > 0.05 Women 11 16,83±1,73 11 19.55 ± 4.37 0,85 > 0.05 3rd level Men 12 28,75±3,58 13 30.95 ± 3.59 0,76 > 0.05 Women 11 18,95±1,94 12 22.14 ± 2,03 2,82 <0.05 4. Discussion According to research, it is established that CrossFit in the process of physical education of high school student’s 2nd -3rd class level could help to improve the level of physical readiness. there are a considering changes in level indicators development of the maximum dynamic force of abdominal muscles the press, found mainly a significant improvement, both Men and women of the main groups, and these differences statistically significant (p <0.001). The above is confirmed by the data of (Adel et al. 2019; Mokhtar et al. 2019; Saddek et al. 2020), according to which it was found that during physical exertion, muscle hypertrophy occurs as a result of adaptive-trophic influence (Mukund et Subramaniam 2020; Teplov 1982), which is characterized by an increase in thickness and denser packaging of contractile elements of muscle fiber(Haun et al. 2019; Narici et al. 1996). Thus, studies (Annesi et al. 2005; Belkadi et al. 2019; Krivoruchko et al. 2018a; Masliak et Mameshina 2018a) indicate that the introduction of functional exercises in the main part of the lesson contributed to a significant improvement in strength abilities of high school students. Analyzing the indicators of the level of endurance development, obtained after the application of the variable module "CrossFit"(Drake et al. 2017), it was determined that the data of schoolchildren of the main groups have significantly improved and are significant differences (p <0.001) (Bala et Petrova 2019; Kozina et al. 2018). Thus, according to (Khabibullayevich 2019; Rink, French, et Tjeerdsma 1996), this is due to the fact that at the study age, the body's oxygen regimes become more economical during exercise, significantly increases the body's ability to work "in debt", ie increases anaerobic productivity(Jobling et al. 1993; Millet et al. 2002; Schaun et al. 2018). Examining the indicators of coordination of movements obtained after the pedagogical experiment, it was found that students of high school age of the main groups, have significantly improved and are reliable. the nature of the differences (p <0,01; 0,001). The above is not confirmed by the data of (Krivoruchko et al. 2018c), according to 13 which it is determined that in the period of 16-17 years continues to improve motor coordination to the level of adults, and differentiation of muscular effort reaches a maximum level. Thus, according to (Kozina, Ol’khovyj, et Temchenko 2016; Sobko, Ulaeva, et Yakovenko 2016), it was found that under the influence of physical education lessons with elements of sports orientation significantly improved the agility of high school students(Benhammou et al. 2021; Faigenbaum et Mediate 2006; Galan et al. 2017; Sobko et al. 2016; Yanci et al. 2013). Analyzing the indicators of the level of development of the frequency of movements obtained after the introduction of CrossFit exercises, a significant improvement of the data in high school students of the main groups was revealed (p <0.05–0.001). Thus, scientists(Alexander et Vladislav 2016; Belkadi 2019; Mikolajec et al. 2012) argue that various sports have a positive effect on the development of speed abilities. Analyzing the indicators of the level of development of mobility in the hip joints obtained after the experiment, it was determined that in high school students of the main groups,have significantly improved and have significant differences (p <0.05; 0.001). According to (Базилевич et Тонконого 2019), it is determined that at this age ossification of the skeleton are not yet completed, which provides a fairly high level mobility and significant reserves available for improvement flexibility(Segal, Hein, et Basford 2004), especially under the influence of CrossFit exercise. The data obtained by our study are consistent with the indicators of (Chen et al. 2013; Trautner et al. 2005), according to which there are positive changes in the level of development of flexibility in boys and girls of 3ed level classes, under the influence of health fitness. 5. Conclusions Our conducted research shows the positive influence of the CrossFit exercises released by our study at the 2nd and 3rd level classes of secondary school students. The effectiveness of using CrossFit in secondary school is beyond doubt. This allows us to optimize and diversify the combination of physical exercises, naturally increasing interest in systematic physical education at the secondary schools; differentiated approach to the choice of exercise intensity is based on the level of initial physical fitness of the training students; motivates to improve health, maintain physical fitness, play sports and build muscles, increase activity and vitality, the ability to cope with physical fatigue. The proposed program, planned for 8 weeks of classes, was designed for young people aged 16-17. Students who recently graduated from middle school did not have significant physical achievements. Having a low level of physical fitness of students at the beginning of the research, for 8 weeks of motivated use of the CrossFit program, we achieved a significant improvement in the physical condition of the students. Thus, the study conducted by us, allows us to talk about the effectiveness of training, built on the basis of a motivated choice of the target CrossFit program. These results are important for physical education teachers, fitness professionals and athletes. Prospects for further research in this area can be realized by determining the level of physical health of high school students under the influence of CrossFit exercises. 14 Limitations: The main limitation in this study is that only 2nd and 3rd level classes were tested. In an ideal study there would be a variety of student tested; various ages. And also for the short period of the CrossFit programme. Another limitation could have been the number of students tested in comparison to the number of participants in the secondary high school observed. In order to obtain very widely accepted results, a large amount of data is needed, and a large number of students must be seen. While this study may not fulfil those requirements, it adds to a larger body of research that will hopefully lead in that direction. Acknowledgments We thank the Algerian General Directorate for Scientific Research and Technological Development (DGRSDT-MESRS) for their co-operation and help in setting up the study. also, for maintaining and supporting finances and quality of research. References Adel, Belkadi, Benchehida Abdelkader, Cherara Alia, Benbernou Othman, Sebbane Mohamed, et Asli Houcin. 2019. « The Effect of High-Intensity Exercise on Changes of Blood Concentration Components in Algerian National Judo Athletes ». Acta Facultatis Educationis Physicae Universitatis Comenianae 59(2):148‑60. doi: 10.2478/afepuc-2019-0013. Adel, Belkadi, Charara Alia, et Zerf Mohammed. 2020. « Algerian Judo Competition Modality and Its Impacts on Upper and Lower Limbs Strength Perseverance and Limitations ». Orthopedics and Sports Medicine: Open Access Journal 3(4):293‑99. doi: 10.32474/OSMOAJ.2020.03.000168. Alexander, Bolotin, et Bakayev Vladislav. 2016. « Factors that determine high efficiency in developing speed and strength abilities of female hurdlers. » Journal of Physical Education & Sport 16(3). Andrieieva, Olena, Olena Yarmak, Mariia Palchuk, Olena Hauriak, Lidiia Dotsyuk, Alexandr Gorashchenco, Iryna Kushnir, et Iaroslav Galan. 2020. « Monitoring the morphological and functional state of students during the transition from middle to high school during the physical education process ». Journal of Physical Education and Sport 20(1):2110‑17. Annesi, James J., Wayne L. Westcott, Avery D. Faigenbaum, et Jennifer L. Unruh. 2005. « Effects of a 12-Week Physical Activity Protocol Delivered by YMCA after- School Counselors (Youth Fit for Life) on Fitness and Self-Efficacy Changes in 5- 12-Year-Old Boys and Girls ». Research Quarterly for Exercise and Sport 76(4):468‑76. doi: 10.1080/02701367.2005.10599320. Bala, Tetiana, et Anhelina Petrova. 2019. « Analysis of the attitude of high school students to innovative types of motor activity in the system of school physical education ». Slobozhanskyi herald of science and sport 7(4 (72)):13‑16. 15 Batorova, Dominika, et Jan Sørensen. 2019. « Methodological review of model-based cost-effectiveness analyses of school-based interventions to increase pupils’level of physical activity ». Journal of Physical Education 30. Beboucha, Wahib, Adel Belkadi, Abdelkader Benchehida, et Ali Bengoua. 2021. « The anthropometric and physiological characteristics of young algerian soccer players. » Acta Facultatis Educationis Physicae Universitatis Comenianae 61(1). Belkadi, Adel. 2019. Proceedings of IAC in Vienna 2019. Czech Institute of Academic Education z.s. Belkadi, Adel, Abdelkader Benchehida, Otmane Benbernou, et Mohamed Sebbane. 2019. « Competencies and Training Needs and Its Impact on Determining the Professional Skills of Algerian Elite Coaches ». International Journal of Physical Education, Fitness and Sports 8(3):51‑61. doi: 10.26524/ijpefs1936. Belkadi, Adel, Benbernou Othman, Sebbane Mohamed, Benkazdali H. M, Jaques Gleyse, Belkadi Adel, Benbernou Othman, Sebbane Mohamed, Laroua Abdelhafid, Benkazdali H. M, et Jaques Gleyse. 2015. « Contribution to the Identification of the Professional Skills Profile of Coaches in the Algerian Sport Judo System ». International Journal of Sports Science 5(4):145‑50. Benhammou, S., L. Mourot, M. I. Mokkedes, A. Bengoua, et A. Belkadi. 2021. « Assessment of Maximal Aerobic Speed in Runners with Different Performance Levels: Interest of a New Intermittent Running Test ». Science & Sports. doi: 10.1016/j.scispo.2020.10.002. Bodnar, I. R., et A. S. Andres. 2016. « Tests and standards for express-control of physical fitness and health of middle school age pupils ». Pedagogics, psychology, medical-biological problems of physical training and sports 20(4):11‑16. Cacioppo, Marine, Sandra Bouvier, Rodolphe Bailly, Laetitia Houx, Mathieu Lempereur, Johanne Mensah-Gourmel, Christèle Kandalaft, Roxane Varengue, Alain Chatelin, et Jacky Vagnoni. 2021. « Emerging health challenges for children with physical disabilities and their parents during the COVID-19 pandemic: The ECHO French survey ». Annals of physical and rehabilitation medicine 64(3):101429. Chen, Li-Jung, Kenneth R. Fox, Po-Wen Ku, et Chih-Yang Taun. 2013. « Fitness change and subsequent academic performance in adolescents ». Journal of School Health 83(9):631‑38. Drake, Nicholas, Joshua Smeed, Michael J. Carper, et Derek A. Crawford. 2017. « Effects of Short-Term CrossFitTM Training: A Magnitude-Based Approach. » Journal of Exercise Physiology Online 20(2). Faigenbaum, Avery D., et Patrick Mediate. 2006. « Effects of medicine ball training on fitness performance of high school physical education students ». Physical Educator 63(3):160. 16 Fedewa, Alicia L., et Soyeon Ahn. 2011. « The effects of physical activity and physical fitness on children’s achievement and cognitive outcomes: a meta-analysis ». Research quarterly for exercise and sport 82(3):521‑35. Galan, Yaroslav, Igor Nakonechnyi, Yurii Moseichuk, Ivan Vaskan, Yurii Palichuk, et Olena Yarmak. 2017. « The analysis of physical fitness of students of 13-14 years in the process of physical education ». Granacher, Urs, Thomas Muehlbauer, Britta Doerflinger, Ralf Strohmeier, et Albert Gollhofer. 2011. « Promoting strength and balance in adolescents during physical education: effects of a short-term resistance training ». The Journal of Strength & Conditioning Research 25(4):940‑49. Harold W. Kohl, I. I. I., Heather D. Cook, Committee on Physical Activity and Physical Education in the School Environment, Food and Nutrition Board, et Institute of Medicine. 2013. Physical Activity and Physical Education: Relationship to Growth, Development, and Health. National Academies Press (US). Haun, Cody T., Christopher G. Vann, Brandon M. Roberts, Andrew D. Vigotsky, Brad J. Schoenfeld, et Michael D. Roberts. 2019. « A critical evaluation of the biological construct skeletal muscle hypertrophy: size matters but so does the measurement ». Frontiers in physiology 10:247. Hsieh, Shu-Shih, Chih-Chien Lin, Yu-Kai Chang, Chun-Ju Huang, Tsung-Min Hung, et T. City. 2017. « Effects of childhood gymnastics program on spatial working memory ». Medicine and science in sports and exercise 49(12):2537‑47. Jobling, M., B. M. Baardvik, J. S. Christiansen, et E. H. Jørgensen. 1993. « The effects of prolonged exercise training on growth performance and production parameters in fish ». Aquaculture International 1(2):95‑111. Kaur, Harleen, Tushar Singh, Yogesh Kumar Arya, et Shalini Mittal. 2020. « Physical Fitness and Exercise During the COVID-19 Pandemic: A Qualitative Enquiry ». Frontiers in Psychology 0. doi: 10.3389/fpsyg.2020.590172. Khabibullayevich, Boltaboev Hamidullo. 2019. « Theoretical foundations of a healthy lifestyle, physical education and physical activity of pupils ». European Journal of Research and Reflection in Educational Sciences Vol 7(12). Kolokoltsev, M. M., S. S. Iermakov, et M. Jagiello. 2018. « Comparative analysis of the functional characteristics and motor qualities of students of different generations and body types ». Pedagogics, psychology, medical-biological problems of physical training and sports 22(6):287‑95. Kozina, Zh L., Ya A. Goloborodko, Yu D. Boichuk, I. M. Sobko, O. O. Repko, T. A. Bazilyuk, I. A. Prokopenko, I. F. Prokopenko, A. I. Prokopenko, et N. G. Tararak. 2018. « The influence of a special technique for developing coordination abilities on 17 the level of technical preparedness and development of psycho-physiological functions of young volleyball players 14-16 years of age ». Kozina, Zh L., O. M. Ol’khovyj, et V. A. Temchenko. 2016. « Influence of information technologies on technical fitness of students in sport-oriented physical education ». Physical education of students 20(1):21‑28. Krivoruchko, N. V., I. P. Masliak, T. M. Bala, I. N. Skripka, et V. I. Honcharenko. 2018a. « The influence of cheerleading exercises on the demonstration of strength and endurance of 15-17-year-olds girls ». Physical education of students 22(3):127‑33. Krivoruchko, N. V., I. P. Masliak, T. M. Bala, I. N. Skripka, et V. I. Honcharenko. 2018b. « The influence of cheerleading exercises on the demonstration of strength and endurance of 15-17-year-olds girls ». Physical education of students 22(3):127‑33. Krivoruchko, N. V., I. P. Masliak, T. M. Bala, I. N. Skripka, et V. I. Honcharenko. 2018c. « The influence of cheerleading exercises on the demonstration of strength and endurance of 15-17-year-olds girls ». Physical education of students 22(3):127‑33. Lalia, C., Alrawi R. Ali, B. Adel, H. Asli, et B. Othman. 2019. « Effects of caloric restriction on anthropometrical and specific performance in highly-trained university judo athletes ». Physical education of students 23(1):30‑36. Long, Margaret. 2017. The Effects of a Six Week Lumbopelvic Control and Balance Training Program in High School Basketball Players. West Virginia University. Mameshina, Margarita. 2019. « Differentiation of the content of classes on physical education, taking into account indicators of physical health and physical preparedness of students in grades 7–9 ». Slobozhanskyi herald of science and sport 7(6 (74)):26‑31. Masliak, I. P., et M. A. Mameshina. 2018a. « Physical health of schoolchildren aged 14- 15 years old under the influence of differentiated education ». Pedagogics, psychology, medical-biological problems of physical training and sports (2). Masliak, I. P., et M. A. Mameshina. 2018b. « Physical health of schoolchildren aged 14- 15 years old under the influence of differentiated education ». Pedagogics, psychology, medical-biological problems of physical training and sports (2). Masliak, Irina, Natalia Krivoruchko, Tatiana Bala, Yuriy Horchaniuk, et Olena Korchevska. 2019. « Efficiency of using cheerleading for flexibility development at female students of teacher training college ». Maulder, Peter S. 2018. « Relationship between maturation, strength, movement competency and motor skill performance in adolescent males ». 18 Mikolajec, Kazimierz, Zbigniew Waskiewicz, Adam Maszczyk, Bogdan Bacik, et Piotr Kurek. 2012. « Effects of stretching and strength exercises on speed and power abilities in male basketball players ». Isokinetics and Exercise Science 20(1):61‑69. Millet, Gregoire P., Bernard Jaouen, Fabio Borrani, Et Robin Candau. 2002. « Effects of concurrent endurance and strength training on running economy and VO2 kinetics ». Medicine & Science in Sports & Exercise 34(8):1351‑59. Mohammed, Berria, Kasmi Bachir, Seghir Nour Eddine, et Belkadi Adel. 2018. « Study of LDH adaptations associated with the development of Speed endurance in basketball players U19 ». International Journal of Applied Exercise Physiology 7(3):35‑43. Mokhtar, M., B. Adel, B. Wahib, A. Hocine, B. Othman, et S. Mohamed. 2019. « The effects of tow protocol cold water immersion on the post match recovery and physical performance in well-trained handball players ». Pedagogics, psychology, medical-biological problems of physical training and sports 23(6):288‑95. Mukund, Kavitha, et Shankar Subramaniam. 2020. « Skeletal muscle: A review of molecular structure and function, in health and disease ». Wiley Interdisciplinary Reviews. Systems Biology and Medicine 12(1):e1462. doi: 10.1002/wsbm.1462. Narici, Marco V., H. Hoppeler, B. Kayser, L. Landoni, H. Claassen, C. Gavardi, M. Conti, et P. Cerretelli. 1996. « Human quadriceps cross‐sectional area, torque and neural activation during 6 months strength training ». Acta physiologica scandinavica 157(2):175‑86. Palichuk, Yurii, Lidiia Dotsyuk, Oksana Kyselytsia, Yuriy Moseychuk, Oleh Martyniv, Olena Yarmak, et Yaroslav Galan. 2018. « The influence of means of orienteering on the psychophysiological state of girls aged 15-16-years ». Petrova, Anhelina. 2021. « Impact of crossfit exercises on the level of physical preparedness of high school-age pupils ». Slobozhanskyi herald of science and sport 9(2):109‑21. Petrova, Anhelina, et Tetiana Bala. 2020. « The cardiorespiratory system state of the 10th-11th grade boys after the introduction of the variable module “Crossfit” ». Slobozhanskyi herald of science and sport 8(3):20‑33. Pricop, Adrian Daniel, Raluca Pelin, Oroles Florescu, Et Mariana Mezei. s. d. « Diversification of sports activities in technical higher education by improving sports facilities ». Prysiazhniuk, Stanislav, Oleksandr Pryimakov, Sergii Iermakov, Dmytro Oleniev, Jerzy Eider, et Natalija Mazurok. 2021. « Influence of weekly physical exercises on indicators of biological age of student’s youth ». Physical education of students 25(1):58‑66. 19 Reiman, Michael P., et Robert C. Manske. 2009. Functional testing in human performance. Human kinetics. Rink, Judith E., Karen E. French, et Bonnie L. Tjeerdsma. 1996. « Foundations for the learning and instruction of sport and games. » Journal of teaching in Physical Education 15(4):399‑417. Root, Hayley, Ashley N. Marshall, Anna Thatcher, Alison R. Snyder Valier, Tamara C. Valovich McLeod, et R. Curtis Bay. 2019. « Sport specialization and fitness and functional task performance among youth competitive gymnasts ». Journal of athletic training 54(10):1095‑1104. Saddek, Benhammou, Jérémy B. J. Coquart, Laurent Mourot, Belkadi Adel, Mokkedes Moulay Idriss, Bengoua Ali, et Mokrani Djamel. 2020. « Comparison of Two Tests to Determine the Maximal Aerobic Speed ». Acta Facultatis Educationis Physicae Universitatis Comenianae 60(2):241‑51. doi: 10.2478/afepuc-2020-0020. Schaun, Gustavo Z., Stephanie S. Pinto, Mariana R. Silva, Davi B. Dolinski, et Cristine L. Alberton. 2018. « Whole-body high-intensity interval training induce similar cardiorespiratory adaptations compared with traditional high-intensity interval training and moderate-intensity continuous training in healthy men ». The Journal of Strength & Conditioning Research 32(10):2730‑42. Seefeldt, Vern, Robert M. Malina, et Michael A. Clark. 2002. « Factors affecting levels of physical activity in adults ». Sports medicine 32(3):143‑68. Segal, Neil A., Jane Hein, et Jeffrey R. Basford. 2004. « The effects of Pilates training on flexibility and body composition: an observational study ». Archives of physical medicine and rehabilitation 85(12):1977‑81. Sibley, Benjamin A. 2012. « Using sport education to implement a CrossFit unit ». Journal of Physical Education, Recreation & Dance 83(8):42‑48. Sibley, Benjamin A., et Jennifer L. Etnier. 2003. « The relationship between physical activity and cognition in children: a meta-analysis ». Pediatric exercise science 15(3):243‑56. Sobko, I. N., L. A. Ulaeva, et Y. A. Yakovenko. 2016. « Factorial structure of physical rehabilitation group students’ complex fitness ». Physical education of students (2):32‑37. Strong, William B., Robert M. Malina, Cameron JR Blimkie, Stephen R. Daniels, Rodney K. Dishman, Bernard Gutin, Albert C. Hergenroeder, Aviva Must, Patricia A. Nixon, et James M. Pivarnik. 2005. « Evidence based physical activity for school-age youth ». The Journal of pediatrics 146(6):732‑37. 20 Teplov, S. I. 1982. « [Mechanisms of the adaptive and trophic effects of the sympathetic nervous system on brain vessels and tissue] ». Fiziologicheskii zhurnal SSSR imeni I. M. Sechenova 68(2):275‑83. Trautner, Hanns M., Diane N. Ruble, Lisa Cyphers, Barbara Kirsten, Regina Behrendt, et Petra Hartmann. 2005. « Rigidity and flexibility of gender stereotypes in childhood: Developmental or differential? » Infant and Child Development: An International Journal of Research and Practice 14(4):365‑81. Varea, Valeria, Ana Riccetti, et Marcela Siracusa. 2021. « The Powerpuff Girls: making it as early career academics in physical education ». Journal of Gender Studies 1‑12. Vlasova, Sofiya. 2017. « Innovations in the physical education of schoolchildren ». Фізичне виховання, спорт і культура здоров’я у сучасному суспільстві (2):51‑56. Voloshina, L. N., V. L. Kondakov, A. A. Tretyakov, E. N. Kopeikina, M. Cretu, et V. Potop. 2018. « Modern strategies for regulating the motor activity of preschool and school age children in the educational space ». Pedagogics, psychology, medical- biological problems of physical training and sports (2). World Medical Association. 2013. « World Medical Association Declaration of Helsinki: Ethical Principles for Medical Research Involving Human Subjects ». JAMA 310(20):2191‑94. doi: 10.1001/jama.2013.281053. Yacine, Zenati, Benbernou Othmane, Belkadi Adel, Sebbane Mohamed, Benchehida Aabdelkader, et Cherara Lalia. 2020. « Functional Movement Screening as a Predictor of Injury in Highly Trained Female’s Martial Arts Athletes ». Polish Hyperbaric Research 71:67‑74. doi: 10.2478/phr-2020-0012. Yanci, Javier, Raúl Reina, Asier Los Arcos, et Jesús Cámara. 2013. « Effects of different contextual interference training programs on straight sprinting and agility performance of primary school students ». Journal of sports science & medicine 12(3):601. Bazilevich, N., et O. Tonkonogo. 2019. "The effect of fitball aerobics on the level of physical fitness and functional state of female students of pedagogical universities". Bulletin of the Carpathian University. Series: Physical culture (31):3‑8.