Effects Of Neuromuscular Fatigue On The Strategies Of Men And Women Athletes' Feet Landing

PURPOSE:The purpose of this study is to analysis the kinematics and kinetics of landingmovement, and then discusses the influence of neuromuscular fatigue process onlower limb kinematics and kinetics, and then discusses the gender difference oflanding strategy under the similar level of neuromuscular fatigue with natural landingof lower limb, in order to analyze the biomechanics under the different levels offatigue state down the influence of the strategy for lower limb mechanics.METHODS:Ten male and10female Shanghai University of sport athletes had3Dlower-limb-joint kinematics and kinetics recorded during3landings, both before、under and after fatigue. Mean subject-based initial-contact and peak stance-phasekinematic and normalized (mass x height) kinetic parameters were quantified beforeand after fatigue and submitted to a two-way Repeated measures to determine for themain effects of gender and fatigue. A Bonferroni corrected alpha level of0.05wasadopted for all statistical comparisons.RESULTS:1) The initial-contact hip flexion and ankle plantar flexion angle had a significantdifference of gender. Male had a larger initial-contact hip flexion angle comparedwith female. Female had a larger initial-contact ankle plantar flexion anglecompared with male.2) Female landed with more knee abduction angle compared with male.3) There is a gender differences in the timing of stance-phase peak vertical groundreaction force, for female, peak vertical ground reaction force consistentlyoccurred at the end of stance compared with male, a noticeable temporal shift inVGRF was evident in females after fatigue.4) The peak vertical ground reaction force had a significant difference of gender.Female lander with more VGRF compared with male,5) The peak knee extension moment had a significant difference of gender.Femalelander with great peak knee extension moment compared with maleCONCLUSIONS:Fatigue-induced modifications in lower-limb control may increase the risk of ninjury during landings.1）Female landed with less hip and knee flexion ROM compared with men. increase the stiffness of lower limbs in the process of landing, caused by a lack of femaleathletes on muscle strength, this strategy may help to prevent to fall to the ground,but on the other hand the increase of the stiffness also can increase the tension ofligament; male tend to adopt when be born larger hip knee touchdown point ofview, because in this way can make better use of muscle to buffer the groundimpact to reduce the stress of the ligament.2）Female`s landing strategies are more dependent on the ankle ROM to buffer, butrestricted its ankle mobility will cause ankle buffering capacity decline, moreenergy transfer to the knee and hip joint, and the knee and hip joint is in a state ofmore straight (compared to men), therefore more likely to cause the risk of kneeand hip injury.3） Fatigue-induced modifications in lower-limb make female landed with the verticalground reaction force of the presence of the peak moment of time will haveobvious moved forward, while men appear time of the peak time will not beaffected by the significance of fatigue.Due to the presence of the non-contact ACLinjuries are usually relatively early in the support phase, so we can think of fatiguecaused by the offset of the peak time of ACL injury risk in women may be animportant factor.