The purpose of study was to identify the presence of strength asymmetries (SA) in young elite soccer players in relation to muscle group (knee extensors (KE) and flexors (KF)) and limb preference (dominant vs. non-dominant limb). Forty-one U16 national team soccer players (mean age 15.7±0.3 years, body height 177.9±6.6 cm, body weight 68.2±7.9 kg) participated in this study. Assessments were performed on a Cybex Humac Norm isokinetic dynamometer in concentric contraction. We noted the degree of SAs in the bilateral ratio of quadriceps and hamstrings and in the ipsilateral ratio of the dominant (DL) and non-dominant (NL) legs. Bilateral deficits of KFs were higher (9.02–12.61 %) than those of KFs (6.32–7.15 %). The percentage of SA (>10 %) in knee extensors was 19.5– 31.7 %. The percentage of SA (>10 %) in knee flexors was 36.6–51.2 %. At the lowest velocity, there was a significantly higher prevalence of SAs in KFs than in KEs (χ2= 4.11, p<.05). The ipsilateral ratio was lowest at the lowest velocity regardless of limb dominance (DL: 58.95–63.27 %, NL: 56.58–60.11 %). At each velocity, the percentage of SA was higher for the non-dominant limb (12.2–24.4 %) than for the dominant one (4.9–14.6 %). Despite these differences, we did not find any significantly higher prevalence of SA in the non- dominant limb than in the dominant one (χ2= .35–2.04, p>.05). The results of the study suggest that more than 73.2 % of players have at least one SA. More attention should be paid to knee flexors, where a higher percentage of strength asymmetries were observed; furthermore, a higher percentage of strength asymmetry was seen in the non-dominant lower limb.
KEY WORDS: Muscular strength; Strength Asymmetries; Isokinetic testing; Soccer; Injury prevention.