Sport represents a domain where various functions and effects can be manifested. The sports industry today is characterized by modern technology, especially in the sphere of manufacturing sports props and equipment, which significantly helps its development and progress. The sports industry today exists within the social-economic achievements and power of a society. In essence, it should adapt to the new living conditions, work conditions and the conditions in which business is being conducted. Today, it is necessary to invest more in the offer of the sports industry (athletes, results, equipment, equipment, facilities, diagnostics ...), in order to be more efficient in the form of the final product on the market. The industry must adapt to the conditions of the world market (supply and demand). That is why it is sometimes necessary to also expand the range of constituents in order to win a medal – achieve a top sports result. This article will analyze the phenomenon of the modern sports industry as a business model, its production and the realization of the necessary conditions for achieving top sports results and winning medals at big competitions. Naturally, without unity between numerous external and internal factors no top sports results can be achieved. The authors also deal with an analysis of the factors of the sports industry.

The aim of this study is to investigate the differences in muscle contractile properties measured by the TMG method between top-level football players of different playing positions. The sample consisted of 57 football players from the Serbian Super League, divided into three groups: defenders—DF, midfielders—MF, and forwards—FW. Muscles included in the study were the Rectus Femoris (RF), Vastus Medialis (VM), Vastus Lateralis (VL), Biceps Femoris (BF), and Semitendinosus (ST) of the right (R) and left (L) leg. The TMG parameters used in this study were contraction time (Tc), delay time (Td), relaxation time (Tr), maximal displacement (Dm), and sustain time (Ts). The ANOVA results showed that differences in TMG parameters between top-level football players of different playing positions are small and exist only in the Tr of RF (F = 4.658, p = 0.014), BF (F = 4.433, p = 0.016), and ST muscle (F = 3.808, p = 0.028), and the Tc (F = 3.214, p = 0.048) and Td (F = 3.705, p = 0.031) of the VM muscle. All differences were detected between DF and FW players, and all differences were in the left (non-dominant) leg. The results obtained in this study indicate that the training and selection process in football, from the aspect of functional and mechanical muscle properties, should be similar for all players, regardless of playing position. It has been shown that TMG has relatively low sensitive strength for detecting differences between football players of different playing positions.

BACKGROUND: Information regarding the relationship between methods for assessment of voluntary and involuntary muscle contractile properties is of importance in sport science and medicine. OBJECTIVE: To appraise the concurrent and predictive validity of isokinetic dynamometry and tensiomyography (TMG) in differently trained men and women. METHODS: Fifty men and 45 women were divided into three groups: physically inactive, physically active and athletes. Isokinetic testing was performed on knee muscles in concentric mode at 60 and 180[ ]s while tensiomyographic measurements were obtained from the rectus and the biceps femoris muscles. RESULTS: A small, statistically significant correlation was detected between the peak moment and tensiomyography parameters relating to contraction time and maximal displacement (Adj. R[ ] 0.086, [ ] 0.028). CONCLUSION: In general, isokinetic dynamometry and tensiomyography are not related and represent different technologies that measure different contractile properties of muscles. A hierarchical structure of predictive validity at the level of individual variables was detected as a function of gender and training level.

Annual age grouping of children according to their birth year is a common practice of the educational systems of many countries. This variation in birth dates among children grouped in the same generation is known as relative age and its implications on different developmental outcomes are referred to as relative age effects (RAEs). The previous body of research of RAEs in youth populations has focused on sporting samples; however, studies examining RAEs in physical education are scarce. The current study investigates the influence of the RAEs on motor abilities in a sample of adolescent pupils. The results indicate significant differences in motor abilities between relatively older and relatively younger participants of both sexes. Since RAE is an under-researched area in physical education, the results may have substantial implications for PE assessment given the fact that many PE teachers still carry out typical norm-referenced assessments. Possible recommendations for future research are discussed.