Effects of ankle instability type and bilateral leg on lower extremity kinetics during drop-landing

The purpose of this study was to investigate the analysis of the postural stability and leg stiffness according to the ankle instability types and bilateral legs during drop landing. Methods: Total 14 male athletes (n=7: mechanical ankle instability, n=7: functional ankle instability) Participants in the experiment. The leg stiffness, leg length, peak vertical force, loading rate, as well as the DPSI (medial-lateral [ML], anterior-posterior [AP], vertical [V], dynamic postural stability index) during drop landing were calculated. To analyze the variables measured in this study, SPSS version 21.0 was used to calculate the mean and standard deviation, while a two-way ANOVA was used to evaluate the ankle instability types (MAI, FAI) with landing leg (left: dominant, right: non-dominant leg) results. Dimensionless leg stiffness and change of leg lengths showed increased with significantly in non-dominant leg and MAI type than in dominant leg and FAI type. This resulted from decrease in the leg lengths with leg stiff. MLSI showed increased with significantly in dominant leg than in non-dominant leg during drop landing. Mechanically unstable individuals demonstrated increased leg stiffness, which may increase risk of musculoskeletal. Also, mechanically unstable participants demonstrated greater loading rate variability, which may indicate difficulty mitigating landing forces with lax ligaments.