Zoran Handjiski, Eli Handzjska, Mimoza Milenkova

The aims of this study are to determine the ACTN3 genotype and isokinetic characteristics of the knees of soccer players U17.Material and methods: 27 soccer players, aged 16-17 years, were included is this study. The examination was conducted in two days in PZU Kineticus. We determined the ACTN3 genotype from abstracted genomic DNA (RR –speedy muscle fibers, XX-endurance muscle fibers and RX variant – mixed muscle fibers) with taking venous blood and its distribution according with player position. We measured the peak TQ/BW, AG/ANT (H/Q) and deficits in flexion and extension of both knees with isokinetic test on Biodex Pro 4, according with player position. We used descriptive statistics and correlations (p<0.05).Results: The most frequent variant of ACTN3 genotype was RR variant (48,3%), than RX (30%) and XX (26%). The RR variant was mostly represented (57%) in midllefield players and XX variant (37%) in forwards. 59% of players were with insignificant and 41% with significant differences in flexion and extension of both knees, especially in forwards. H/Q of right knee, especially of defenders (67,73%), were above normal values.Discussion: ACTN3 genotype profile could help in process of selection and specialization of young soccer players, suggesting that RR variant of ACTN3 genotype should be mostly presented in forwards. The high H/Q in right knee and mostly represented deficits in flexion of left knee suggested a new strategy and changes in strength training of young soccer players. Conclusions: The distribution of ACTN3 genotype in soccer players was according with the data from the literature, with surprisingly high XX variant in forward players. H/Q of right knee, especially in defenders, was above normal values. The forwards were with the most significant differences between the knees. The most frequent deficits were in flexion, especially in left knee.


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