Abstract

The primary aim of this study was to define the quantitative values of the contractile properties of knee flexor and extensor muscles in highly trained youth football players (U18), measured using tensiomyography (TMG). The examined muscle groups included the biceps femoris (BF), rectus femoris (RF), and vastus lateralis (VL). A secondary aim was to establish descriptive normative dataset of the investigated variables for this age category of football players. The research sample consisted of 25 U18 football players from the top clubs in the Republic of Serbia. TMG variables were measured during the pre-competition phase of the season. The mean values of the measured variables for the BF muscle were: contraction time (Tc) – 25.78 ± 7.71 ms, delay time (Td) – 21.85 ± 3.98 ms, maximal radial displacement (Dm) – 5.92 ± 2.49 mm, contraction velocity (Vc) – 0.124 ± 0.212 mm/ms; for the RF muscle: Tc – 27.70 ± 4.22 ms, Td – 23.50 ± 2.75 ms, Dm – 10.54 ± 2.29 mm, Vc – 0.206 ± 0.329 mm/ms; and for the VL muscle: Tc – 22.30 ± 3.04 ms, Td – 21.30 ± 1.53 ms, Dm – 5.42 ± 1.54 mm, Vc – 0.124 ± 0.336 mm/ms. Based on a comparison between U18 players and senior players, it can be concluded that, with respect to the parameters Dm and Vc, which may be associated with training level and muscle tone, senior players demonstrate superior results. Conversely, regarding Tc and Td, which may be related to a higher proportion of fast-twitch fibers and greater muscle contraction speed, youth players achieved better outcomes.

Keywords: tensiomyography, contraction velocity, quadriceps muscles, hamstring