Asymmetry in Hamstring Strength Among Soccer Players During the Swing Eccentric Hamstring Exercise: Implications Across Playing Positions Riego Ruiz, Antonio Ruiz Garces, Carlos Chirosa Ríos, Ignacio Jesús Contreras Díaz, Guido Delgado Floody, Pedro Torres Banduc, Maximiliano A. Reyes Ferrada, Waleska Jerez Mayorga, Daniel Alejandro Functional asymmetry Eccentric Strength Sprin Background: In soccer, the repeated execution of unilateral actions may lead to uneven limb development, promoting the occurrence of asymmetries. However, there is no consensus on the impact of these asymmetries on sports performance or the influence of playing position on their magnitude. Methods: A cross-sectional study was conducted with 33 male federated soccer players (age: 18.42 ± 4.24 years; body mass: 70.23 ± 8.74 kg; height: 1.76 ± 0.07 m; body mass index: 22.6 ± 2.7 kg/m2). Hamstring strength asymmetry between the dominant and non-dominant limbs was assessed using functional electromechanical dynamometer (FEMD) at eccentric velocities of 0.4, 0.8, and 1.2 m/s. Physical performance was evaluated through a 30 m sprint and countermovement jump (CMJ). Differences according to playing position were also analyzed. Results: Significant between-limb differences were found in strength, power, and impulse, with effect sizes increasing as testing velocity rose. No significant differences in asymmetry levels were observed across playing positions, and no correlations were found between hamstring asymmetry and physical performance outcomes. Conclusions: Although functional lower-limb asymmetries were identified in soccer players, these asymmetries did not directly influence performance nor vary across playing positions. The findings suggest that certain asymmetries may represent normal functional adaptations in soccer rather than pathological structural imbalances. 2026-02-13T09:29:42Z 2026-02-13T09:29:42Z 2026-02-12 journal article Riego-Ruiz, A., Ruiz-Garces, C., Chirosa-Ríos, I., Contreras-Diaz, G., Delgado-Floody, P., Torres-Banduc, M., Reyes-Ferrada, W., & Jerez-Mayorga, D. (2026). Asymmetry in Hamstring Strength Among Soccer Players During the Swing Eccentric Hamstring Exercise: Implications Across Playing Positions. Applied Sciences, 16(4), 1837. https://doi.org/10.3390/app16041837 https://hdl.handle.net/10481/110954 10.3390/app16041837 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional MDPI