The Asymmetry Level of Hamstrings Strength in Female U16 Basketball Players

Abstract

Study aim(s): This study aims to assess hamstring strength asymmetry in female basketball players under 16 years old using both bilateral and unilateral Nordic Hamstring Test. The goal is to identify right-left leg strength differences that may influence injury risk and performance, yet often go undetected in regular training.

Methods: The observational study, with a cross-sectional design includes 10 female basketball players under the age of 16 who train regularly with the "United Basketball" U16 team, under the framework of the Kosovo Basketball Federation (KBF). Hamstring strength asymmetry was assessed using the bilateral and unilateral Nordic Hamstring Tests using, with data collected via the My Jump 3 application. The measured parameters included torque (Nm), percentage of maximum torque (% of max τ), breakpoint angle (⁰), and asymmetry level (%). Data were analyzed using SPSS version 27. The statistical methods applied the Shapiro-Wilk test, descriptive statistics, percentiles, Pearson correlation, independent t-test, and a standard formula for calculating asymmetry level.

Results: A significant negative correlation was found between body weight ─ attributable to muscle mass ─ and asymmetry (r = 0.681, p = 0.030). BMI showed a similar non-significant trend (r = 0.614, p = 0.059). In contrast, height and lever length exhibited weak correlations with asymmetry. Torque was higher in the right leg (455.24 Nm) compared to the left leg (370.85 Nm). The measured asymmetry was 5.09%, indicating a slight dominance of the right leg.

Conclusion: In U16 female basketball players, a 5% asymmetry between the left (370 Nm, 102.3°) and right leg (455 Nm, 103.5°) in torque and breakpoint values suggests an acceptable level of functional variation. This asymmetry is likely influenced by muscle mass, which contributes to strength balance and neuromuscular control. These findings highlight the importance of targeted unilateral hamstring training to reduce injury risk in dynamic, sport-specific movements.