The association of dorsiflexion flexibility on knee kinematics and kinetics during a drop vertical jump in healthy female athletes

PURPOSE: While previous studies have examined the association between ankle dorsiflexion flexibility and deleterious landing postures, it is not currently known how landing kinetics are influenced by ankle dorsiflexion flexibility. The purpose of this study was to examine whether ankle dorsiflexion flexibility was associated with landing kinematics and kinetics that have been shown to increase the risk of anterior cruciate ligament (ACL) injury in female athletes. METHODS: Twenty-three female collegiate soccer players participated in a preseason screening that included the assessment of ankle dorsiflexion flexibility and lower-body kinematics and kinetics during a drop vertical jump task. RESULTS: The results demonstrated that females with less ankle dorsiflexion flexibility exhibited greater peak knee abduction moments (r = -.442), greater peak knee abduction angles (r = .355), and less peak knee flexion angles (r = .385) during landing. The range of dorsiflexion flexibility for the current study was between 9° and 23° (mean = 15.0°; SD 3.9°). CONCLUSION: Dorsiflexion flexibility may serve as a useful clinical measure to predict poor landing postures and external forces that have been associated with increased knee injury risk. Rehabilitation specialists can provide interventions aimed at improving dorsiflexion flexibility in order to ameliorate the impact of this modifiable factor on deleterious landing kinematics and kinetics in female athletes. LEVEL OF EVIDENCE: II.