Aim of this paper was to examine the contribution of football experience and the self-assessment of tactical/technical skills and social competencies on the perceived self-efficacy in junior and senior football players. A total of 164 football players from Bosnia & Herzegovina have taken part in the research, 79 of which were professional senior players and 85 were professional U18 (junior) players. Three measuring instruments were used in the research: A questionnaire on general information, a self-assessment scale of self-efficacy for football players and a scale for estimating tactical/ technical and social competencies in football was used to gather data. Based on the results and the conducted analyses, it is indicative that the model that encompasses the length of football experience and a self-assessment of tactical/technical and social competencies in senior football players contributed around 8.5% to the total explanation of perceived self-efficacy. In senior players, the length of experience has a greater significance in perceived self-efficacy compared to the perceived success in performing football elements. The set model doesn’t have an equal contribution in junior players, where the model entirely contributed with 14.3% of the explanation of perceived self-efficacy, and the perceived success of performing football elements also has a statistically significant contribution. So, the model which encompasses football experience and the perceived success in performing football elements (tactical/technical and social competencies in football) is not equally predictive in junior and senior players.

The goal of this paper is to determine the injury frequency rate in professional football players in leagues and national competitions by analyzing existing papers. We have chosen 21 articles according to the PRISMA method from the Google Scholar, ResearchGate Scopus, and Web of Science databases that fit both inclusion and exclusion criteria. We have discussed the following four segments based on the content of the selected papers: 1) An analysis of the injury frequency rate on the level of national teams, 2) An analysis of the injury frequency rate in club leagues, 3) A comparison of the injury frequency rate in matches and in practice, and 4) An analysis of the injury frequency rate in male versus female football players. The paper concludes that major national team tournaments have the highest injury frequency rate and that the probability of injury is four to five times higher in a match than in practice. The injury frequency rate in female players is lower than in male players regardless of the type of competition (national teams or leagues).

Conflict is an integral part of sport, and it implies a normal occurrence in communication and relationship between athletes and coaches. The main aim of this paper was to present a conflict analysis of the coach-athletes relationship, but also its impact on the achievement of sports results. The review article analysed nine works that directly studied interpersonal relationships between coaches and athletes. Research results suggest that conflict is evident and inevitable, as well as expected since coaches spend a lot of time with athletes, and pass through the training process, but also the competition period, when athletes are exposed to greater pressure because of the competition itself. Timely response and adequate response to conflict can greatly contribute to improving relations and even better sports results.

Uvod Informisanost o nivou treniranosti sportista, te uzrocima i posljedicama takvog stanja, bitna je za njihov uspjeh. Poznato je da fudbaleri u igri ostvare veći broj kratkih sprinteva, te da primjenjuju različite načine vođenja lopte, pravolinijski i sa promjenom smjera kretanja. Struktura agilnosti s loptom je mnogo složenija u odnosu na takvo kretanje bez lopte (Sporiš, Milanović, Trajković, & Joksimović, 2011). Brzina i eksplozivna snaga se smatraju preduslovom za uspjeh u omladinskom fudbalu (Reilly, Bangsbo, & Franks, 2000), naglašavajući pritom ubrzanja na kratkim udaljenostima. Visina i tjelesna težina su značajno povezane sa fi zičkom izvedbom u slučaju mladih fudbalera ( Mathisen & Petersen, 2015). Ipak se sa sigurnošću ne može izolovati neka osobinu ili sposobnost koja donosi odlučujuću prednost u utakmici. Fudbaleri su tjelesno lakši od osoba koje žive sedentarnim načinom života (Popović, Akpinar, Jaksic, Matic, & Bjelica, 2013), ali i niži u odnosu košarkaše, odbojkaše i rukometaše juniorske kategorije (Masanovic & Vukasevic, 2009; Masanovic, 2018). Međutim, u sportovima gdje se traži velika brzina kretanja, nagla promjena pravca u velikoj brzini kretanja, grubi sudari sa protivnikom (fudbal i hokej), tjelesna visina ne samo da nije dominantna, nego je u određenoj mjeri i nepovoljna (Bjelica & Fratrić, 2011). Međusobni odnos tjelesne visine i težine (body mass index), te udio masne komponente (% fat mass) u ukupnoj tjelesnoj masi, za trenere može biti važna informacija. Optimalne vrijednosti BMI-a mogu rezultirati u poboljšanju opšteg nivoa tjelesne i anaerobne snage (Nikolaidis, 2014). Fudbaleri imaju povoljan sadržaj mišića sa niskim nivoom tjelesnih masti (Popovic, Bjelica, Jaksic, & Hadzic, 2014). Ipak, višak tjelesnih masti stvara nepotreban teret i umanjuje učinkovitost u igri, te značajno narušava elemente tehnike mladih fudbalera (Nemčić, Fiorentini, & Sporiš, 2018). Vrijednosti tjelesnih masti za vrhunske fudbalere su u prosjeku 7-12%, te su niže nego u slučaju sedentarnih ljudi, ali su takođe više u odnosu na trkače u sportovima izdržljivosti (Shephard, 1999.). Pored optimalizacije voluminoznosti mišića, na količinu potkožnog masnog tkiva se može uticati dopunskim treningom (Conroy i Earle, 2000), i to djelovanjem u pravcu njene redukcije. S obzirom da se takmičenja omladinskih liga organizuju shodno hronološkoj, a ne biološkoj starosti, često se pojedinci Abstract

The aim of this paper is to determine the differences in the level of morphological characteristics, speed abilities and aerobic endurance according to the team positions of top female football players. The study included 18 female football players (age 21.33±3.67, body mass index 20.94±1.95). Female football players are classified under the following team positions: defenders (n = 7 ; 23±16.4 years), midfielders (n = 6, 20.5±14.3 years) and attackers (n = 5 ; 20±31.3 years). The following tests were used: 0-5m sprint (s), 0-10m sprint (s), 0-20m sprint (s), 0-30m sprint (s) and Beep test. Body mass index (BMI) was calculated based on the ratio of body weight (kg) and body height (cm). Based on the Beep test, the maximum oxygen consumption (VO2max) was calculated and presented in its relative value (ml/kg/min). The attackers had a higher body height (170.1±7.46) and weight (59.60±8.84) than those playing in midfield and defense positions. Also, the attackers were faster in the sprint on the 5m (1.17±.06), 10m (1.91±.06), 20m (3.27±.10) and 30m (4.51±.17) than female players in midfield and defense positions. Midfield players had higher level of VO2max (50.03±2.69) than female players in defensive and offensive team positions. Test results of univariate analysis of variance (ANOVA) showed that there are significant differences in the level of morphological features, speed and aerobic endurance capabilities between the top female football players, regardless of their team position (p>0.05). It is obvious that good speed abilities on short sprint sections as well as high level of aerobic endurance at high intensity are required regardless of players team position in the women’s football. It is important to note that selection for team positions can not only be based on morphological characteristics, speed abilities and aerobic endurance of players. Also, tactical tasks as well as technical characteristics of players need to be considered for selection of team positions in the women’s football.

The aim of this research is to determine the elastic (repulsive) properties of the futsal ball depending on the air pressure in it. Futsal ball of standard dimensions was released on the fl at solid surface from the height of nine meters for four times. At the fi rst release the air in the ball was under prescribed pressure. At the second release the pressure in the pumped ball is reduced by 5%, at the third reduced by an additional 5%, at the fourth reduced by another 5%. The setting of the experiment was carried by cinema shooting of free fall of the prescribed futsal ball and a series of rebounds after the rejection of solid surfaces. One can conclude that the distance crossed and the total duration of four successive bouncing mostly dependent on inner pressure. In this study, the initial speed of a futsal ball was unchanged and only inner pressures were changed. It was determined how much the height of the rebound is reduced and the duration of the rebound, respectively, depending on the reduction of inner pressure. Overall, it can be concluded that the initial speed of the ball can be increased by increasing the inner pressure in the ball.

Abstract Introduction The aim of the study was to analyse the deviations of the body posture and to assess the occurrence of spine deformities. Additionally, Body Mass Index in school children was related to the trend in postural deformities for different age groups (5-8 years old, n=112; 9-11 years old, n=205; 12-14 years old, n=212) as part of the project “Spine Lab”, granted from the European Commission IPA founds, investigating the importance of public health issues. Methods Body posture was measured using Contemplas 3D software analyser, based on video image trajectory and BIA weight scale (Tanita BC 420). Overall, 17 variables were assessed, and differences were confirmed using MANOVA analysis. Results The results showed that there is a significant difference between age groups for the measured variables (F=9.27; p<0.01; η2=0.26), suggesting a moderate difference across the age span. Conclusion The study results showed that there is a negative trend of increasing Body Mass Index within the first and youngest age group. The fact is that the trend of increasing deformity of the shoulder belt has been noted, often inclining towards the formation of milder forms of kyphotic posture. Other forms of deformity that are accentuated in the survey results are the negative trend of increasing pelvic rotation and pelvis rotation which inclines towards the formation of lordotic posture for all three age groups.