Abstract
This study investigates bilateral and unilateral strength imbalances in elite
young football players across different age categories. A total of 73 licensed
male football players in the U15, U16, U17, and U19 age categories participated
in the study. Imbalances between the legs were assessed by both jump tests and
differences between hamstring and quadriceps strengths. Differences between age
groups were statistically evaluated by one-way analysis of variance and linear
regression analysis. The results showed that the hop test asymmetry index (AI),
Q/Q, and H/H strength ratios decreased from U15 to U17 and increased again at
U19 (p=0.037, p=0.025, p=0.002). Regression analysis
revealed that age significantly influenced the hop test AI (5%), Q/Q strength
ratio (5%), H/H strength ratio (12%), and dominant leg H/Q strength ratio (7%)
(p<0.05). Overall, this study shows that muscle strength
imbalances in young soccer players differ both bilaterally and unilaterally with
age. While bilateral strength differences were relatively balanced in the
U15–U17 age groups, a significant asymmetry was observed in the U19 group. In
terms of unilateral strength, a certain development was observed in the dominant
leg with age, while this development was limited in the nondominant leg.
Keywords
asymmetry index - functional jump test - isometric strength - injury risk
