Exploring Eccentric Hamstring Strength: Peak Force, Torque, and Impulse Metrics in Elite Academy Soccer Players

Area of Science:

• Sports Science
• Biomechanics
• Youth Athlete Development

Background:

• Eccentric strength is crucial for injury prevention and performance in soccer.
• Understanding age-related changes and asymmetries in eccentric strength is vital for training.
• Limited data exists on eccentric knee flexor strength in elite youth soccer players.

Purpose of the Study:

• To characterize eccentric strength metrics and bilateral asymmetry index (BAI) of knee flexors in elite youth soccer players.
• To explore correlations between these metrics and demographic characteristics.
• To identify age-related variations in strength and asymmetry.

Main Methods:

• Cross-sectional study involving 132 male elite academy soccer players (13-20 years old).
• Eccentric strength assessed using the Nordic Hamstring Exercise (NHE) with NordBord®.
• Measured relative/absolute peak force (PF), peak torque (PT), eccentric impulse (EI), and calculated BAI.

Main Results:

• Eccentric PF, PT, and EI increased significantly with age.
• BAI decreased from the U17 category onwards.
• Moderate correlations found between PF/PT and body mass (BM)/body mass index (BMI); EI showed weaker correlations with BM.

Conclusions:

• Elite youth soccer players demonstrate higher eccentric hamstring strength than previously reported.
• Strength metrics correlate moderately with body mass and BMI, while impulse correlates weakly.
• Age-related variations in BAI are significant, especially in younger players, highlighting developmental differences.