摘要：Limb asymmetries is the condition which soccer players may suffer from as they perform many actions on one limb. Furthermore,some sensitive and reliable methods to identify lower limb asymmetries are the use of isokinetic dynamometer,the back squat,the unilateral mid-thigh pull and the unilateral jump tasks. Additionally,it is not clear which is the impact of limb asymmetries on physical performance. The aims of the present study were to: 1) compare single-leg countermovement jump (SLCMJ),single-leg long jump (SLLJ),and single-leg triple jump (SLTJ) between dominant (D) and non-dominant (ND) limbs,2) to investigate the relationship between inter-limb asymmetry from the above three unilateral jump tests and 505 test and arrowhead change of direction (COD) performance and 3) to examine the relationship of lateral trunk muscles strength asymmetry with COD performance in young soccer players. Forty-two young male soccer players were separated into two groups (Under 10 - U10 and Under 15 - U15) and each one of them performed a SLCMJ,SLLJ,SLTJ,505 COD test,arrowhead COD test. In order to investigate the relationship between limb asymmetries and performance on unilateral COD tests,paired samples T-test were used and Pearson’s to compare the results of their limbs. In U10 significant differences between limbs were observed on SLCMJ (p=0.024) and on SLTJ (p=0.003). SLTJ asymmetries correlated significant with slower arrowhead test times (p=0.039). In U15 significantly differences between limbs were observed on SLCMJ (p=0.032),on arrowhead test (p=0.016) and on 505 test (p=0.018). Asymmetries during SLCMJ were associated with slower performance on 505 COD test (p=0.017). The results indicated that in these two age groups (U10 and U15) of youth soccer players’ asymmetry detection is test depended. CMJ can be used in both groups for indentify lower limb asymmetries but this study highlight that the SLTJ for the age of U10 and SLCMJ for the age of U15 appear to be the most appropriate jump tests for identifying limb asymmetries. Additionally,the correlation of asymmetries with agility performance,which is very important for player success,indicates that trainers have to check their players for asymmetries and if there is a difference of greater than 10% it should be eliminated with specific and individualized strength and power programs.
关键词：single leg jump;505 test;arrowhead test;performance
