Effects Of Biomechanical Performance Of Lower Limb Joints On The Speed Of Fencing Lunge

Objective: The kinetic and kinematic variables of ankle, knee and hip joints during fencing lunge are critical to the lunge speed. However, the specific effect of each joint to the speed of lunge is not clear. It’s also rarely published that if there is a significant difference between the kinetic and kinematic performances of lower extremities of fencers in different levels. And the reasons leading to the differences are also not clear. The aim of this study is to explore the effect of kinetic and kinematic variables of ankle, knee and hip joints to lunge speed by comparing the kinetic and kinematic performances of lower extremities between elite fencers(EF) and medium-level fencers(MF). Include:(1) to explorethe kinetic and kinematic variables relative to lunge speed.(2)to explore if there is difference in lunge speed between EF and MF and analyze the reasons leading to that difference.(3) to explore if there is difference in kinetic and kinematic performance of lower extremities between EF and MF and analyze the reasons leading to the difference, then discuss the effects of the difference to lunge speed of different-level fencers.Methods: 7 elite fencers and 12 medium-level fencers were asked to perform fencing lunges as fast as possible.Kinematics and ground reaction force of both legs were recorded during lunge movements through Vicon(Motion Analysis Inc., Oxford, UK) and force platform(Kistler, 9287 B, 90×60cm). The post-processing analysis was done using Visual 3D(C-Motion, Inc., Germantown, MD, USA).Results:(1) The horizontal peak velocity of the center of gravity(HPV) is significantly related to the horizontal peak ground reaction force made by pushing off the rear leg(PGRF), the range of motion(ROM) of rear knee joint, the peak power(PP), peak moment(PM) and peak angular velocity(PAV) of rear knee joint, ROM of rear ankle joint, ROM of fore hip joint(p<0.05) during lunge. PP of rear knee joint is the best single predictor of HPV(r2=0.69,p=0.000). PGRF is significantly related to PM, PP, ROM of rear knee joint and PAV of fore hip joint(p<0.05), also tend to significantly related to ROM of rear ankle(r=0.440,p=0.060). PP of rear knee joint is the best single predictor of PGRF(r2=0.51,p=0.001).(2) The HPV, PP and PM of rear knee joint, PGRF, ROM of rear knee and ankle joints of EF are significantly higher than MF.(3) Both of EF and MF group flexed their knee joints in the initial phase of the lunge before extending it. However, MF group showed significantlyhigher initial flexion angle with higher peak extension angular velocity and less time for extending in leading knee compared to EF group(p<0.05).Conclusion:(1) Compared to MF group, the higher HPV of EF group is related to their higher PGRF, and the higher PGRF is depended on higher PM, PP, ROM of rear knee joint and ROM of rear ankle joint.The higher PM, PP of rear knee joint of EF group is related to their better explosive power of extensors of rear leg compared to MF group, pointing out the importance of strengthening explosive power of quadriceps of rear leg for improving HPV. Higher ROM of rear knee and ankle joints during lunge is beneficial forprolonging the effect of GRF, further beneficial for improving HPV.(2) The different kinematic performance of leading knee joint is determined by GRF produced by rear leg. MF group improved PAV of fore knee joint by increasing its flexion before extension to contribute the moving of center of gravity and make up the disadvantage of lower GRF compared to EF group. However, the higher flexion before extension of fore knee joint may be adverse to the effectiveness of lunge during fencing match.