The Effect of Unilateral Practice on Lateral Asymmetry

The purpose of the study was to investigate the effect of unilateral practice on leg lateral asymmetry in soccer kicking of the male students at Ferdowsi University of Mashhad. The subjects were 40 students (18 to 24) who participated in the course of General Physical Education, They did not have any professional and regular experiences in soccer, and their prefered leg was right. They were randomly and equally divided to experimental and control groups. The experimental group practiced with their nonpreferred left leg according to the program for eight weeks and three times a week for one and a half hours per session. The control group had no activities other than those usually performed in their daily life. The subjects performed the task of instep kicking in pre-test, post-tests and retention test 15 days after the practice. The data were analyzed through mixed analysis of variance, repeated measures ANOVA and independent samples T test in experimental and control groups. Results showed that the unilateral practice has caused remarkable increase in the left leg performance and inconsiderable increase in the right leg performance. Also, significant reduction in the index of lateral asymmetry from the pre-test to post-test (p=0.002) and retention test (p=0.003) showed reduction of right leg preference in the experimental group after the unilateral practice. Based on the results, it is assumed that leg preference is task-specific and a result of special limitations in acquisition of a task which basically comes from previous experiences in differential use of the limbs.