High relationships between muscle strength and various forms of jumps are usually based on the research samples of professional athletes or students of sports and physical education. However such studies are less known in the case of recreational women. This study aimed to determine the relationship between isokinetic parameters of knee joint muscle strength with the efficiency of performing vertical jumps. The sample represents a group of 16 healthy and physically active women (age=31.04±3.71; height 168.13±8.34; weight 59.80±9.80). Knee extensors and flexors were evaluated by using an isokinetic dynamometer, while the two-foot vertical jump performance was measured using the Opto Jump System. Pearson's correlation coefficient was used to determine correlation magnitude (p<.05). The obtained results indicated high correlations of the knee extension peak torque dominant leg (KEPT D), knee extension peak torque non-dominant leg (KEPT ND) and knee flexion peak torque non-dominant leg (KFPT ND) with counter movement jump free arms (CMJFA) (r=.525; r=.511; r=.594; p<.05). High correlations was also indicated between KFPT ND with counter movement jump (CMJ) (r=.514; p<.05). Given that these are recreational women, we can assume that the countermovement free arm jump type was the most natural form of expressing their explosive potential. It is certainly important that future studies further examine the relationships between muscle strength and performance of primary and specific motor tasks in recreational women.

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).

Identification of talents in football is one of the most important tasks of coaches in youth football selection. The main focus of this paper was to review the available literature on talent identification in youth football. A systematic review of PubMEd, Medline, ResearchGate and Elsevier databases was performed according to PRISMA guidelines. The following keywords were used: „identification of talents“, „football talent“, „selection in football“, and „management in sport clubs“. Of 137 studies initially identified, of which 17 met the inclusion criteria of the review. Mentioned studies were analyzed and discussion was created with the emphasis on 4 segments: 1) analysis of physiological aspects and identification of talents 2) importance of specific contents for identification of talent 3) biological and chronological age as an important aspect of selection of young players 4) multidisciplinary approach to the selection of young players. It is concluded that process of identification of talents needs to be approached multidisciplinary with all contents of physiological and physical assessment and with specific football contents (SSG and TE-TA contents) respectively. Great role in performance on the field has the biological age, on which coaches need to pay attention to when evaluating quality of players.

This research aimed to determine the isokinetic strength differences between two groups of athletes (karate and track-and-field athletics) and to analyse factors that possibly contribute to the differences. We examined possible differences in peak power output and power ratio between agonist and antagonist thigh muscles of the knee. The sample consisted of 20 respondents: karate athletes (n=10; age 19±2.4) and track-and-field athletes (n=10; age 18±2.6). For this study, a valid test (CV<5%) of the isokinetic strength output of the knee extensors and flexors, was used at the angular velocity of 60°/s. Isokinetic variables: Peak torque in extension for both legs (Nm); Peak torque in flexion for both legs (Nm); Total work for both legs (J); Strength deficit involved/uninvolved leg and agonist/antagonist ratio for involved and uninvolved leg. A t-test for independent samples was used to determine the differences. Statistical significance was set at the conventional 95%. In the sample of examined variables, the first tested group of athletes (karate) achieved higher power output values with the dominant leg, except in the case of the peak torque extensors. In the second tested group of athletes (track-and-field athletics), a higher power output values are registered with dominant leg, except in the case of the total work flexor with almost identical value of dominant and non-dominant leg. In the variables of the peak torque of the dominant leg (p=0.002) and the peak torque of the non-dominant leg (p=0.019), statistically significant differences were noted between two tested groups of athletes (p<0.01, p<0.05). The unilateral relationship of the dominant leg (p=.003) significantly differentiates two groups of athletes (p<0.01). The better performance of track-and-field athletes is probably the result of the specificity of the structure of their motor movement and greater muscular work in training and competition. In contrast, the lower results of peak torque and total work in karate athletes compared to track athletes do not necessarily mean situational inferiority. Evaluation and assessment of knee dynamic stabilizers’ isokinetic profile can lead to the optimal selection of training operators, during the construction of the overall training program for athletes. Results of different outputs of force and strength may indicate a differently shaped approach to training.

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.

PURPOSE: The aim of this study was to examine the reliability, validity and usefulness of the 30–15IFT in competitive female soccer players. METHODS: Seventeen elite female soccer players participated in the study. A within subject test-retest study design was utilized to assess the reliability of the 30–15 intermittent fitness test (IFT). Seven days prior to 30–15IFT, subjects performed a continuous aerobic running test (CT) under laboratory conditions to assess the criterion validity of the 30–15IFT. End running velocity (VCT and VIFT), peak heart rate (HRpeak) and maximal oxygen consumption (VO2max) were collected and/or estimated for both tests. RESULTS: VIFT (ICC = 0.91; CV = 1.8%), HRpeak (ICC = 0.94; CV = 1.2%), and VO2max (ICC = 0.94; CV = 1.6%) obtained from the 30–15IFT were all deemed highly reliable (p > 0.05). Pearson product moment correlations between the CT and 30–15IFT for VO2max, HRpeak and end running velocity were large (r = 0.67, p = 0.013), very large (r = 0.77, p = 0.02) and large (r = 0.57, p = 0.042), respectively. CONCLUSION: Current findings suggest that the 30–15IFT is a valid and reliable intermittent aerobic fitness test of elite female soccer players. The findings have also provided practitioners with evidence to support the accurate detection of meaningful individual changes in VIFT of 0.5 km/h (1 stage) and HRpeak of 2 bpm. This information may assist coaches in monitoring “real” aerobic fitness changes to better inform training of female intermittent team sport athletes. Lastly, coaches could use the 30–15IFT as a practical alternative to laboratory based assessments to assess and monitor intermittent aerobic fitness changes in their athletes.

The aim of this research was to determine the differences in the rate of development of ventilation capabilities in 12 to 15-year-old boys who systematically train football, and boys in the same age group who are not involved in any sports. The research included 40 football players and 40 non-players, divided into chronological age groups U12, U13, U14, and U15. Ventilation capabilities are represented with 10 parameters: forced vital capacity, forced vital capacity in percentage predicted, volume of air exhaled during the first second, volume of air exhaled during the first second in percentage predicted, Tiffeneau index, percentage of the predicted Tiffeneau index, forced expiratory flow, forced expiratory flow 25-75% of FVC, forced expiratory flow 75-85% of FVC, and maximum expiratory flow. The difference between the arithmetic mean of groups and the development rate of the variables is determined by one-way analysis of variance (ANOVA). Non-players have a higher and faster growth in value for most variables until the age of 13, followed by a gradual stagnation and decline in values, while football players have a more balanced growth in values until the age of 13, and they experience the maximum in development at 14 years of age, after which it begins to decline slightly. The obtained values confirm that boys who are participating in systematic sport training have a continuous rate of development of pulmonary ventilation, and have greater capacity values, as well as better airway patency.

Influence of charring on the fire resistance of timber columns is under consideration in this Graduation thesis. In the second section timber charring and the phenomenon of the pyrolysis of timber is explained. Further, the literature review in the field of empirical and numerical models of timber charring is given. In the third section, the main procedures of the structural fire-buckling design in accordance with EN 1995-1-1:2005 are analysed. In the fourth section, the numerical and empirical models are further explained through numerical examples. The calculations in numerical examples are carried out with a computer program developed in Matlab environment. The empirical models are carried out using program MS Excel. Based on the heat transfer analysis in the numerical model a distribution of char is calculated. The empirical equations for determination of char distribution are given in the second section. The calculated distribution of char is used then to calculate the buckling capacity of timber columns exposed to fire. In the fifth section the selected empirical and numerical models are compared to each other. The conclusions are given in the last section.