Effects Of Gait Retraining On In Vivo Kinematics Of The Foot Arch,Metatarsophalangeal Joint And The Length Of Plantar Fascia During Running

Purpose:Plantar fasciitis is one of the most common running injury.Most studies indicated that repeated overload/impact of v GRF and insufficient foot muscle strength are important causes of plantar fasciitis,so does switching from reafoot strike(RFS)to forefoot strike(FFS)running reduce the risk of plantar fasciitis injury? In addition,studies have found that forefoot running will increase foot muscle strength,so is the forefoot running action itself or caused by it,such as foot muscle strength,which has a positive effect on the plantar fascia(PF)? Therefore,it is necessary to explore the effect of FFS running.At present,the traditional rehabilitation methods for plantar fasciitis mainly include foot strength training and PF stretching.Therefore,from the causes of plantar fasciitis,whether running posture transformation combined with foot function training can reduce the plantar fasciitis risk? In addition,the close relationship among the MLA,first MTPJ,and PF during running.Current research methods such as traditional motion capture,ultrasound,cadaver experiments,and single-plane fluoroscopy systems are difficult to accurately explore the motion of the PF,arch,and metatarsophalangeal joint.In recent years,the dual fluoroscopic imaging system(DFIS)has emerged as a viable tool to capture in vivo bone motion in sports analysis and medical rehabilitation.The system can noninvasively analyze individual joints with high reproducibility without being affected by the errors caused by skin and soft tissues.Therefore,the purpose of this study is: 1)To explore the influence of different strike patterns on the kinematics of the arch,metatarsophalangeal joint and PF,as well as the relationship between the three movements by high-speed DFIS;2)Is gait retraining possible to strengthen the mechanical properties of PF? 3)To explore the changes in the arch,metatarsophalangeal joint and PF after gait retraining combined with foot functional training,whether it is conducive to strengthening its mechanical properties?Methods:Study 1,the high-speed DFIS(100Hz)and a 3D force platform(2000Hz)were used to acquire X-ray images and GRF data of the foot bones of 30 healthy male runners(15 rearfoot strikers and 15 forefoot strikers)during the running support phase with their self-selected strike simultaneously(3m/s).Then establishing a 3D bone model and coordinate system from the CT image of the bones,as well as the starting and ending points of the PF and the contact points of the sesamoid,combined with3D-2D registration techniques to obtain the six degrees of freedoms data of the arch(the first metatarsal relative to the calcaneus),first metatarsophalangeal joint(the first phalanx relative to the first metatarsal)and the length of PF.Study 2,the high-speed DFIS and a 3D force platform(2000Hz)were used to acquire X-ray images and ground reaction force data of the foot bones of 15 healthy male runners(rearfoot strikers)during running with RFS and FFS strike patterns simultaneously.Study 3,the high-speed DFIS(100Hz)and a 3D force platform(2000Hz)were used to acquire X-ray images and ground reaction force data of the foot bones of 32 healthy male rearfoot striker(16 in the experimental group and 16 in the control group)during running(3m/s)with their self-selected strike patterns before and after12-week gait retraining simultaneously.The experimental group wore uniformly distributed five-finger minimal shoes for running with FFS,and at the same time performed foot strength and plantar fascia stretching training with gradually increasing load,while the control group did not do any changes maintained the original foot strike pattern and running miles.Two-way ANOVA with repeated measures was used to compare the effects of 12-week gait retraining on the vivo kinematics of arch,metatarsophalangeal joint and PF.Results:1.Compared with habitual RFS runners,1)the range of motion(ROM)of medical/lateral,anterior/posterior,plantarflexion /dorsiflexion,adduction/abduction of the arch increased for FFS runners(P < 0.05);2)the ROM of anterior/posterior,superior/inferior,plantarflexion/dorsiflexion,adduction /abduction of the first metatarsophalangeal joint increased for FFS runners(P < 0.05);3)the maximum strain,maximum length and the power of PF increased for FFS runners(P < 0.05).2.There are some similar results between the immediate FFS and habitual FFS running: compared with RFS 1)the ROM of the medical/lateral,anterior/posterior,plantarflexion /dorsiflexion,adduction/abduction of the arch,and the ROM of anterior/posterior,superior/inferior,plantarflexion/ dorsiflexion of the first metatarsophalangeal joint,the length changes of PF increased significantly during running with immediate FFS;there are also some differences between the immediate FFS and the habitual FFS running.2)the ROM of the superior/inferior,adduction/abduction,and maximum eversion angle of the arch,the ROM of the anterior/posterior of the first metatarsophalangeal joint,and the maximum length of PF increased significantly during FFS running(P < 0.05);the ROM of plantarflexion/dorsiflexion during propulsion phase of the arch,and the abduction angle of the first metatarsophalangeal joint reduced significantly during FFS running(P < 0.05).3.1)The conversion ratio of the forefoot strike running was 53.3%,and no runners were injured after 12-week gait retraining;2)the 12-week training improved the toe flexor muscle strength,which increased by 36.1% in the experimental group and 21.8% in the control group;3)the 12-week gait training increased the ROM of the anterior/posterior,plantarflexion /dorsiflexion of the arch,decreased the ROM of adduction/abduction of the first metatarsophalangeal joint,and the change in the length of PF and average strain during the entire stance phase also increased significantly(P < 0.05).Conclusion:1.Running with FFS may increase the energy storage and release of the arch and plantar fascia,as well as the push-off effect of the metatarsophalangeal joint.Meanwhile,FFS enhances the mechanical properties of the plantar fascia potentially.In addition,FFS runners had greater toe flexor strength.2.Immediate FFS running potentially strengthens the cushioning capacity of the arch and the energy storage and release,improved the push off role of metatarsophalangeal joints.Meanwhile,PF stored and released more elastic energy,which strengthened the mechanical properties of PF.It further shows that the effect of immediate FFS running on the arch,metatarsophalangeal joint and PF is similar to that of habitual FFS running,but there are also some differences that may be caused by the incompatibility of RFS runners for immediate FFS running.Therefore,an appropriate and long-term gait retrainning would be used by RFS runners to transform to run with FFS.3.The 12-week gait retraining is effective and safe to strengthen foot muscles of runners.The gait retraining strengthens the foot muscle strength,increases the deformation of the foot arch and the length of PF,and further indicates that the effect of gait retraining tends to be the FFS running.