Lower Extremity Biomechanical Comparison Analysis of Single Leg Drop Landing among Normal Foot and Flat Foot

Purpose:The purpose of this study is to compare and analyze the differences in biomechanical function and energy absorption of the lower extremity in the sagittal plane when single leg drop landing between groups with flat foot and normal foot.Methods: Twenty-eight healthy men in their 20s were classified into 13 with flat foot and 15 with normal foot through evaluation of navicular drop test.Using a motion analysis system, loading rate (N/sec), peak vertical ground reaction force (N/body weight [BW]), sagittal plane hip, knee, and ankle joint range of motion (), peak moment (Nm/BW), peak joint power (W/BW) and peak joint work (J/BW) were calculated and analyzed during single leg drop landing.Results: During single leg drop landing, the flat foot and normal foot groups showed no significant differences in loading rate, peak vertical ground reaction force, hip and knee joint range of motion, peak knee and ankle joint moment, peak joint power, and peak joint work (p 0.05).However, the flat foot group showed greater ankle range of motion and peak hip joint flexion moment compared to the normal foot group (p=0.040 and p=0.018, respectively). Conclusion:The flat foot group shows sagittal plane landing mechanics that are different from the normal foot group during single leg drop landing and appears to try to distribute shock by relying on the distal joint compared to the normal foot group.