Lower Limb Functional Asymmetries in Young Soccer Players: Do Differences Exist Between Different Age Groups?

Background Functional asymmetries of the lower limbs(FA) have been recognised as a potential source of injury risk of in soccer players;moreover a difference in strength performance between the lower limbs exceeding 15% is considered an injury risk factor. Preventative strategies should be integrated into young football player training regimes. Table 1. Young soccer players: mean age 9.1±0.1 years. n.athletes>15% Total %>15% % others Hop 25 227 11,2 88,8 Triple 19 227 8,4 91,6 Side 33 227 14,5 85,5 Table 2. Young soccer players: mean age 11.2±0.1 years *p>0.05. n.athletes>15% Total %>15% % others Hop 27 200 13,7 86,3 Triple 16 200 8,3 91,7 Side 37 200 18,5 81,5 Objective To assess the presence of FA in the lower limbs and evaluate whether the percentage of subjects presenting asymmetries exceeding 15% increases with age. Design Cross-sectional studies. Setting Youth sports. Participants 427 young soccer players: 9.1±0.1 years, 36.3±6.5 kg, 137.9±7.1cm (n=227) and 11.2±0.1 yrs, 43.8±9.7 kg, 148.9±9.1 cm (n=200). Risk factor assessment Monopodalic jump ; all three versions were employed: Single (SI), Triple (TR) and Side hop(SE) is considered a valid indicator of FA in the lower limbs. Main outcome measurements Strength in each of the lower limbs was assessed by means of the SI, TR and SE test; the percentage of FA between the lower limbs was calculated using the formula proposed by Yamamoto, 1993: (jump dominant-limb-jump non-dominant limb)/jump dominant-limb*100. Results The percentage valuesare summarised in tables 1 and 2. Conclusions The highest percentage of subjects presenting asymmetries was detected in the 11yr-olds. Comparing the results for the two age groups revealed a statistically significant difference for the SideHop test.