Biomechanical Analysis of Landing from Counter Movement Jump and Vertical Jump with Run -Up in the Individuals with Functional Ankle Instability

Ankle sprain is one of the most common sport injuries in lower extremities. It frequently occurs in landing phase when athletes perform jumping. The counter movement jump and straddle jump are common jumping strategies often used in baseball and volleyball games. Recurrent ankle sprain frequently leads to a chronic disability, the functional instability. The purpose of this study was to investigate the joint kinematics and kinetics of lower extremities in counter movement jump and straddle jump, and compare the differences between the individuals with functional ankle instability and healthy people. VICON612 motion analysis system and two AMTI force plates were used in this study. Straddle jump showed significantly shorter time to peak force, greater loading rate and greater ground reaction force than counter movement jump during landing. Differences on landing impulse between counter movement jump and straddle jump were found in the functional instability group but not in healthy control group. Based on our findings, the likelihood of injury might be greater in the straddle jump than in counter movement jump. In order to maximally reduce the risk of sports injury, counter movement jump would be recommended as a more suitable jumping strategy for the individuals with functional ankle instability due to the lower ground reaction forces and loading rates in lower extremities.