| Objective:The interaction between the end links of the limb and the outside world,the extension to flexion of the limb,the prolongation of the force and the reduction of the impact are called cushioning movements,which are a fundamental part of sporting techniques.The foot is the starting point of the human movement chain and plays a vital role in cushioning movements as it is in direct contact with the ground and provides initial cushioning.As the most common method of physical correction,orthotic insoles theoretically adjust the skeletal force lines of the ankle in the standing position so that the foot is in a neutral position,but the role of orthotic insoles in everyday cushioning movements is still unclear.The study aims is to analyse the possible changes in lower limb movement characteristics due to arch deficiency in people with flat feet,based on transitional and terminal cushioning movements.The study also aims to investigate the effect of 3D orthotic insoles on the biomechanical characteristics of the lower limbs of flatfoot patients during the two types of cushioning manoeuvres,to guide movement techniques for flatfooted people to participate in sports and to provide a theoretical basis for the customisation of orthotic insoles.Methods:The study selected 15 male university students with flexible flat feet as the experimental group and 15 males with undamaged normal feet as the control group.The experimental group wore both minimalist shoes and minimalist shoes with 3D orthotic insoles for biomechanical testing.The control group wore only minimalist shoes and underwent biomechanical testing.Kinematic,kinetic and surface electromyographic data were collected for both transitional and terminal cushioning movements using a plantar pressure test board,3D motion capture,3D dynamometer and wireless surface electromyography tester.insoles on the biomechanical characteristics of the lower limb for transitional and terminal cushioning movements respectively,with the significance level set at(P<0.05).Results:(1)Lower limb kinematic parameters during transitional cushioning manoeuvres.Compared with the control group,the change in ankle joint angle was greater in the experimental group than in the control group during the walking and running phases(P<0.05);the change in knee joint angle was smaller in the experimental group than in the control group during the initial landing phase,the whole-foot support phase and the stirrup-extension phase during the running phase(P<0.05);the change in hip joint angle was smaller in the experimental group than in the control group during the whole-foot support phase during the running phase(P<0.05).In the experimental group,after the 3D orthotic insole intervention,the change in ankle joint angle after the whole foot support phase was less than that before the intervention(P<0.05);the change in knee joint angle during the initial landing phase was less than that before the intervention(P<0.05),and the change in hip extension angle after the intervention during the forefoot touch phase and whole foot support phase was less than that before the intervention(P<0.05).(2)Foot control parameters during transitional cushioning manoeuvres.Compared with the control group,the amount of change in longitudinal arch angle was greater in the experimental group(P<0.05)and the contact area of the midfoot was greater in the experimental group(P<0.05)during the whole-foot support and stirrup-extension-off phase;compared with the control group,the percentage of time during the initial landing phase decreased in the experimental group(P<0.05);the percentage of time during the stirrup-extension-off phase increased in the experimental group(P<0.05);compared with the control group,the percentage of time during the initial landing phase increased in the experimental group(P<0.05).Compared with the control group,the amount of change in heel bone valgus was reduced in the initial landing phase,forefoot touch phase,whole foot support phase and stirrup extension phase during running(P<0.05).After the 3D orthopaedic insole intervention,the amount of change in heel bone valgus was reduced in the experimental group during the initial landing phase during walking(P=0.011);during the whole foot support phase during running,the amount of change in heel bone valgus angle was reduced in the experimental group after the orthopaedic insole intervention(P<0.001);during the initial landing phase,the amount of change in longitudinal arch angle was smaller in the experimental group than before the intervention(P<0.05);during the initial landing phase The amount of plantar pressure deflection after the intervention was less than that before the intervention(P<0.05)in the experimental group during the initial landing phase and the stirrup extension phase.(3)Lower limb movement parameters of the ending cushion movement.Compared with the control group,the amount of change in longitudinal arch angle decreased(P<0.05),the amount of change in heel valgus angle increased(P<0.05),the amount of change in ankle dorsiflexion angle decreased(P<0.05)and the amount of change in knee flexion angle increased(P<0.05)in the experimental group.In the experimental group,the amount of change in hip flexion angle,knee flexion angle,ankle dorsiflexion angle and longitudinal arch angle was less than that before the intervention in the experimental group(P<0.05);the amount of change in heel valgus angle in the experimental group was greater than that before the intervention in the experimental group(P<0.05),and the maximum angular velocity of the ankle joint after the intervention in the experimental group was greater than that before the intervention in the experimental group(P<0.05).(4)Ending cushion action landing stability parameters.Compared to the control group,the standardised root mean square amplitude values of the anterior tibialis and lateral gastrocnemius heads and the ankle joint co-activation ratio were greater in the experimental group during the pre-activation and post-activation phases(P<0.05);the APSI index was reduced in the experimental group compared to the control group(P<0.001)and the DPSI stability index was reduced(P=0.028);compared to the control group,the experimental group had a reduced loading rate(P< 0.05)and reduced time to peak compared to the control group(P<0.05).The standardised root mean square amplitude activation levels and ankle co-activation ratios of the anterior tibialis,lateral head of the gastrocnemius and medial femoral muscles were greater in the experimental group after the 3D orthopaedic insoles intervention than before the intervention(P<0.05);the APSI index was reduced in the experimental group after the 3D orthopaedic insoles intervention(P=0.043).Conclusion:(1)There are kinematic compensatory adjustments in the lower limbs of the flexible flatfoot population during transitional and terminal cushioning manoeuvres,(amount of change in hip-knee-ankle joint angle,hip-knee-ankle joint angular velocity).(2)During the transitional cushioning manoeuvre,the foot control of the flexible flatfoot group was reduced,as evidenced by a reduction in the amount of change in heel valgus,an increase in the amount of change in longitudinal arch angle and an increase in midfoot area,suggesting that the reduced arch of the flatfoot group caused a change in the kinematic characteristics of the lower limb,which is essentially a chain reaction of the lower limb as a whole.(3)During the ending cushioning action,the stabilising effect of the ankle joint in flexible flatfoot patients was enhanced,as shown by the reduction of the angular velocity and angular change of the ankle joint,and the compensatory increase of the knee joint flexion amplitude to achieve the cushioning effect,suggesting that flexible flatfoot people achieve cushioning through the coordination of all joint movements.(4)In transitional cushioning movements,the 3D orthotic insole can adjust the plantar pressure stress point,reduce forefoot impulse and increase midfoot impulse and midfoot area.It also improves the ankle force line,provides arch support,reduces the amount of change in the longitudinal arch angle,reduces heel valgus and reduces the amount of plantar pressure deflection.(5)In the end cushioning manoeuvre,after the 3D orthotic insole intervention,the flexible flatfoot patient landed in a stiff manner: the amount of change in hip,knee and ankle joint angles was reduced,the cushioning effect of each joint became worse,and the load on each joint of the lower limb increased. |
