超等长阻力训练对足踝屈肌肌构筑学及生物力学特征影响的研究

Effects of plyometric resistance training on flexors’muscle architecture and their biomechanics in foot&ankle

目的:探讨超等长阻力训练对足踝屈肌横截面积、体积、羽状角等的影响,观察足底肌力迁移和跖屈肌三元素应变、刚度、做功等的变化,为深入理解训练引起肌-腱复合体构筑和生物力学特征变化的机制及意义提供新的思路。方法:将18名健康男性青年高级花样跳绳运动员随机分成实验组和对照组,对实验组实施跖、趾屈肌超等长阻力训练。于训练前、后对小腿三头肌、跟腱和足底固有肌做影像学测量,计算肌纤维厚度、横截面积、体积等;测试趾屈肌力,计算肌力增加率及肌力/横截面积比值;测试踝单关节活动和下肢多关节活动运动学、动力学及小腿三头肌影像学,计算腓肠肌外侧头各弹性元成分的应变、刚度、做功等参数。结果:训练后实验组小腿三头肌厚度、羽状角和足底固有肌横截面积均明显增加(P<0.05),跟腱横截面积没有明显变化(P>0.05);2~5趾屈力增加率明显大于1~5趾屈力增加率(P<0.01),2~5趾屈力/趾短屈肌横截面积的比值明显提高(P<0.05)。不同条件下腓肠肌外侧头肌-腱复合体各成分的被动刚度均未发生明显变化(P>0.05),主动刚度均明显提高(P<0.05),以大负荷(P<0.01)和快速应变(P<0.01)时提高最显著。肌纤维拉长应变明显降低(P<0.05),大负荷时降低最显著(P<0.05)。腱膜应变和滞后均未发生明显变化(P>0.05)。肌腱拉长速度未发生明显改变(P>0.05),缩短速度明显升高(P<0.05),弹性回缩率明显提高(P<0.05)。结论:超等长阻力训练能优化肌-腱复合体的构筑,较小的肌纤维体积增加即可获得较大的力量增幅;能增强支撑后期推进力,并稳固内侧纵弓;能增加肌-腱复合体的弹性,对大负荷和快速拉长-缩短周期运动表现更加有利。超等长阻力训练具有易化肌-腱复合体能量吸收和促进能量快速转化的双效性作用。

Objective:To explore effects of plyometric resistance training on plantar muscles cross-sectional area,thickness and pinnate angle and examine the changes in foot force transfer and strain,stiffness,work in flexor muscle.By this study we will present a newer researching way for insighting into the mechanism and significance of training-induced changes in muscle-tendon complex architecture and biomechanics.Methods:18 male health young elite figure rope skipping athletes were randomly divided into experimental and control groups.Plyometric resistance training program was used in plantar and toe flexor muscles of experimental group subjects.Imageology of triceps surae muscle,achilles tendon,intrinsic foot muscles were measured before/after training and parameters of muscle thickness,cross-sectional area,volume etc.were calculated.Toe flexion force was tested for calculating the increasing rate of force and the force/cross-sectional area rate.Dynamics,kinetics,triceps surae muscle imageology during single-joint test in ankle and multi-joint test in leg were tested for calculating strain,stiffness,work etc.of each elastic element in lateral gastrocnemius.Results:After training,thickness and pinnate angle of triceps surae muscle and cross-sectional area of intrinsic foot muscles were all significantly increased(P<0.05).There’s no obvious change in tendon cross-sectional area(P>0.05).Increasing rate()of toe flexion force was more obviously in 2~5 than in 1~5(P<0.01).2~5 toe flexion force/flexor digitorum brevis cross-sectional area rate was significantly increased(P<0.05).Passive stiffness of each element in lateral gastrocnemius was not significantly changed when tested under different conditions(P>0.05)but their active stiffness were significantly increased(P<0.05),the most obvious exhibition were under heavy load(P<0.01)and fast strain(P<0.01)conditions.Fascicle elongation was significantly decreased(P<0.05),the most obvious exhibition was under heavy load(P<0.05)condition.There’re no significant changes in aponeurosis strain and hysteresis(P>0.05).There’s no significant change in tendon elongating velocity(P>0.05)but there were significant elevation in shortening velocity(P<0.05)and in elastic recoil rate(P<0.05).Conclusion:Architecture of muscle-tendon complex can be optimized through plyometric resistance training,moreover smaller increasing in volume can bring about greater force.Also propulsive force during later contact phase can be improved and medial longitudinal arch can be stabilized.Elasticity of muscle-tendon complex can be enhanced,which would be more advantageous to stretch-shortening cycle sport performance under heavy-loaded and fast conditions.Plyometric resistance training has double effect in facilitating energy absorption and expediting energy transformation.