Examining the intrinsic foot muscles'capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping  

作　　者：Ross Smith Glen Lichtwark Dominic Farris Luke Kelly 

机构地区：[1]School of Human Movement and Nutrition Sciences,The University of Queensland,Brisbane,QLD 4072,Australia [2]Sport and Health Sciences,College of Life and Environmental Sciences,The University of Exeter,Exeter,EX12LU,United Kingdom

出　　处：《Journal of Sport and Health Science》2023年第5期639-647,F0003,共10页运动与健康科学（英文）

基　　金：funded by an Australian Research Council Linkage Grant(LP160101316),in collaboration with Asics Oceania and The Australian Sports Commission。

摘　　要：Background:During human locomotion,a sufficiently stiff foot allows the ankle plantar flexors to generate large propulsive powers.Increasing foot stiffness(e.g.,via a carbon plate)increases the ankle’s external moment arm in relation to the internal moment arm(i.e.,increasing gear ratio),reduces plantar flexor muscles’shortening velocity,and enhances muscle force production.In contrast,when activation of the foot’s intrinsic muscles is impaired,there is a reduction in foot and ankle work and metatarsophalangeal joint stiffness.We speculated that the reduced capacity to actively control metatarsophalangeal joint stiffness may impair the gearing function of the foot at the ankle.Methods:We used a tibial nerve block to examine the direct effects of the intrinsic foot muscles on ankle joint kinetics,in vivo medial gastrocnemius’musculotendinous dynamics,and ankle gear ratio on 14 participants during maximal vertical jumping.Results:Under the nerve block,the internal ankle plantar flexion moment decreased(p=0.004)alongside a reduction in external moment arm length(p=0.021)and ankle joint gear ratio(p=0.049)when compared to the non-blocked condition.Although medial gastrocnemius muscle-tendon unit and fascicle velocity were not different between conditions,the Achilles tendon was shorter during propulsion in the nerve block condition(p<0.001).Conclusion:In addition to their known role of regulating the energetic function of the foot,our data indicate that the intrinsic foot muscles also act to optimize ankle joint torque production and leverage during the propulsion phase of vertical jumping.

关 键 词：Ankle biomechanics Ankle gearing Foot biomechanicsTagedEnd 

分 类 号：R87[医药卫生—运动医学]