The Effect of a Plyometric Training Program on the Lower Extremity Functional Symmetry of Soccer Players with a History of Lateral Ankle Sprain

An ankle sprain produces two-way defects that increase the risk of secondary damage to the non-injured limb. Hence, the purpose of this study was to investigate the effect of plyometric training (PT) on lower extremity functional symmetry of soccer players with a history of lateral ankle sprain. In this semi-experimental study, 20 male soccer players with a history of one and two-grade external ankle sprain were selected by using sampling method. PT were performed for 6 weeks. To evaluate the functional asymmetry between the lower extremities functional tests including single hop test, triple hop test, crossover hop test, 6m hop test and multiple test were used. The lower extremity symmetry index (LSI) formula was used to assess the degree of asymmetry in healthy and injured leg. Paired t-test was used to compare the performance between the lower limbs and compare the average percentage of lower extremity symmetry. The results of this study showed that there was a significant difference between two legs in the pre-test. A healthy leg had a better performance than the injured leg in single hop test (p=0.011), triple hop test (p=0.017), crossover hop test (p=0.001), 6m hop test (p=0.001), and multiple hop test (p=0.001); while the post-test showed no significant difference between the lower extremities. The results of paired t-test showed that there was a significant difference between the average of LSI in the pre and post-tests in single hop test (p=0.024), triple hop test (p=0.039), a crossover hop test (p=0.031), 6m hop test (p=0.004) and multiple hop test (p=0.001). The results indicated that injured and dominant leg function led to functional asymmetry in two legs, which PT could compensate for this functional asymmetry.