Neuromechanical properties of the triceps surae in young and older adults
Neuromechanical properties of the triceps surae in young and older adults
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DOI：
10.1016/j.exger.2013.07.007
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发表时间：
2013-11-01
影响因子：
3.9
通讯作者：
Lichtwark, Glen A.
中科院分区：
文献类型：
--
作者：
Barber, Lee A.;Barrett, Rod S.;Lichtwark, Glen A.
本研究的目的是比较自愿和不自愿的力量产生能力的小腿三头肌在健康的年轻人和老年人参与者在等长和等速收缩。超声波被用来测量内侧腓肠肌（MG）在最大自愿等长收缩和超最大等长抽搐收缩在整个可用的运动范围内，以及等速同心和离心收缩在四个踝关节的速度在五个踝关节的角度。足底屈肌的最大自主激活使用抽搐内插技术进行评估。在最大自主等长收缩、超大等长收缩和向心性收缩期间，老年人的峰值足底屈肌扭矩分别显著低于年轻参与者的42%、28%和43%。未检测到偏心扭矩产生的年龄相关差异。考虑到年龄相关的小腿三头肌肌肉体积的差异，年龄相关的峰值跖屈肌扭矩赤字的最大自愿等长，超最大抽搐，向心性收缩分别为24%，19%和24%。这些与年龄相关的扭矩差异不能用MG肌束的扭矩-长度-速度行为、被动跖屈肌扭矩-角度特性、跖屈肌神经驱动力下降或胫前肌拮抗性共激活来解释。健康老年人的等长和同心跖屈肌扭矩的残余缺陷可能涉及肌肉质量降低。在老年人离心收缩期间，检测到MG肌束长度较长以及MG肌束速度较低时的超大抽搐扭矩显著降低，这可能是老年人报告的跟腱顺应性增加的函数。(C)2013 Elsevier Inc. All rights reserved.
The aim of this study was to compare voluntary and involuntary force generating capacity of the triceps surae muscles in healthy young and older adult participants during isometric and isokinetic contractions. Ultrasound was used to measure medial gastrocnemius (MG) fascicle length during maximal voluntary isometric contractions and supra-maximal isometric twitch contractions at five ankle angles throughout the available range of motion, as well as isokinetic concentric and eccentric contractions at four ankle velocities. Maximum voluntary activation of the plantar flexors was assessed using the twitch interpolation technique. Peak plantar flexor torque was significantly lower in older adults compared to young participants by 42%, 28% and 43% during maximal voluntary isometric contractions, supra-maximal isometric twitch and concentric contractions respectively. No age-related differences in eccentric torque production were detected. When age-related differences in triceps surae muscle volume determined from MRI were taken into account, the age-related peak plantar flexor torque deficits for maximum voluntary isometric, supra-maximal twitch, and concentric contractions were 24%, 19% and 24% respectively. These age-related differences in torque were not explained by torque-length-velocity behaviour of the MG muscle fascicles, passive plantar flexor torque-angle properties, decreased neural drive of the plantar flexor muscles or antagonistic co-activation of the tibialis anterior muscle. The residual deficit in isometric and concentric plantar flexor torques in healthy older adults may involve reduced muscle quality. A significant reduction in supra-maximal twitch torque at longer MG fascicle lengths as well as a lower MG fascicle velocity during eccentric contractions in older adults was detected, which could possibly be a function of the reported increased Achilles tendon compliance in older adults. (C) 2013 Elsevier Inc. All rights reserved.