Effect of ankle range of motion modification on dynamic valgus index during a monopodal squat in female soccer players

The purpose of this study was to determine the effect of simulated ankle range of motion modification on the dynamic valgus index (DVI) of female soccer players during a monopodal squat. A second objective compared the frontal plane projection angles (FPPA) of hip and knee to identify the greatest contribution to the DVI.The dominant leg (DL) and non-dominant leg (NDL) were evaluated in 16 female soccer players during a monopodal squat, under Basal conditions: «without wedge» (WW); Restrictive: «with dorsiflexor wedge» (DW) and Facilitator: «with plantiflexor wedge» (PW) of ankle. With the Kinovea software, the DVI was identified by adding the hip and knee FPPA. The three conditions in the dominant leg and non-dominant leg, the FPPA in each condition were compared and effect sizes were determined. No condition showed differences in DVI in DL vs. NDL. In DL, DVI increased with large effect in DW and decreased with large effect in PW compared to WW and DW. In NDL, DVI increased with large effect in DW compared to WW and PW. In both legs, hip FPPA was higher than knee FPPA in all conditions. It is concluded that the simulated restriction of ankle dorsiflexion is effective for an increase in DVI, while the facilitator allows its decrease with greater effect on NDL.The hip is the joint with the greatest contribution to the DVI, independent of condition.