Associations Between Bone Age, Body Composition and Physical Performance in Icelandic 12‐Year‐Old Female Soccer Players

Biological maturation significantly influences physical development and performance, with notable differences between sexes. Research using objective measures, such as bone age (BA) assessed with X-ray to evaluate maturity and dual-energy X-ray absorptiometry (DXA) to assess body composition, remains scarce, particularly in females. This study investigated the associations between BA, body composition and physical performance in 12-year-old female soccer players. In total, 89 players (M_age 11.89 ± 0.33 years) from ten local soccer clubs across the greater Reykjavík area participated. BA, measured with X-ray, indicated biological maturity, whereas DXA assessed body composition. Physical performance was measured with a 40-m linear sprint, the countermovement jump (CMJ) and the Yo-Yo intermittent recovery test (IR1-test). Results showed that BA had a small negative correlation with 40-m sprint time (r = -0.253, p = 0.017) but not with other performance tests. Total fat mass and fat percentage positively correlated with 40-m sprint time (r = 0.351 and r = 0.566) and negatively with CMJ height (r = -0.534 and r = -0.632) and peak power (r = -0.490 and r = -0.636; all p < 0.001). Fat-free mass and fat-free mass index were negatively correlated with 40-m sprint time (r = -0.299 and r = -0.301; both p = 0.004) but not with other tests. No body composition measures correlated with the IR1-test. These findings emphasise the importance of understanding female-specific maturation patterns and their impact on physical performance, highlighting the need for targeted research and tailored training programmes for youth female athletes.