The Effects Of The Functional Foot Exercise On The Arch Shape And Running Biomechanics

Objective:In the analysis of the longitudinal arch muscles strength of runners,the cushioning running shoes and rear-foot strike running pattern are two important factors.However,the negative effect of these two factors on the longitudinal arch muscle strength need to be explored.In addition,regarding the plantar muscle strength training,many studies only use foot muscle strength training or shoes as an intervention method.There is a lack of combining local foot muscle training and global foot functional exercises,which cannot guarantee the diversified development of foot muscle function.This research aimed to explore whether the rear-foot strike running with cushioning shoes could affect the muscle strength of the longitudinal arch.Then,investigated the effect of the 12-week functional foot exercise(foot muscle strength training + forefoot running)on the arch morphology,toes flexion strength,arch kinematics during rear-foot strike running & forefoot strike running,and lower limb biomechanical changes during forefoot strike running.Method:In study one,13 nonhabitual running subjects and 13 habitual rear-foot strike with wearing modern running shoes runners were all required to test the hallux flexion,the lesser toe flexion strength and the metatarsophalangeal joints strength.In study two,26 runners who exhibited habitual rear-foot strike with modern running shoes were divided into intervention group and control group.The intervention group and the control group performed foot morphological test,foot muscle strength test,foot kinematics test,and running biomechanical analysis before and after the intervention.The intervention group performed a 12-week functional foot exercise which included foot muscle strength training and forefoot running.The control group did not change the original exercise habit.The vernier caliper,modified dynamometer,and self-made foot-metatarsophalangeal joint strength tester were used to measure the foot morphological characteristics,hallux flexion,and lesser toe flexion strength,metatarsophalangeal joints plantar muscle group strength.The foot kinematics data during rear-foot strike and forefoot strike running gait,and lower limb joints kinematic and kinetic data during forefoot strike running gait were synchronously collected using a motion capture system and Kistler 3D force platforms.Results:1.The absolute and relative strength of the metatarsophalangeal joints plantar muscles showed a decreased trend in the rear-foot strike runners group compared with the nonhabitual running group(P = 0.050;P = 0.077).2.After 12-week functional foot exercises compared with the control group: 1)the normalized navicular heights of the intervention group increased significantly during standing(P = 0.027);2)the absolute and normalized forces of hallux flexion(P = 0.001;P = 0.001)and absolute lesser toe flexion(P = 0.002)were increased significantly in the intervention group;3)during the rear-foot strike running for the intervention group,the maximum arch angle was decreased significantly(P < 0.001),the arch height at touch down(P < 0.001)and the amount of arch height variation were increased obviously(P = 0.027);4)during the forefoot strike pattern,the velocity of the hip at touchdown was decreased(P = 0.001),the amount of knee range of motion variation(P = 0.041)and the velocity of the knee joint at touch down increased significantly(P = 0.009).Conclusion:1.Compared with nonhabitual running subjects,the rear-foot strike runners showed strength decreased trend in the flexor muscles of the metatarsophalangeal joint.2.12-week functional foot exercise increased the normalized navicular height during standing.3.12-week functional foot exercise improved the strength of the plantar flexors effectively.4.12-week functional foot exercise decreased the maximum arch angle,increased the arch height at touchdown and the amount of arch height variation,which meant that the arch showed an adaptive change.5.After a 12-week functional foot exercise,during the forefoot strike pattern,the velocity of the hip at touchdown was decreased,the amount of knee ROM variation and the velocity of the knee joint at touchdown were increased.These changes showed that the landing strategy of the intervention group transitioned from the hip joint to the knee joint,and mainly depended on the knee joint compliance improvement to achieve the cushioning effect.