Kenway Leanne C, Bisset Leanne M, Kavanagh Justin J
Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
Neurobiol Aging. 2016 Jan;37:127-137. doi: 10.1016/j.neurobiolaging.2015.10.003. Epub 2015 Oct 14.
This study observed the effect of visual feedback on between-limb force variability relationships in young and older adults. Abduction force was examined in healthy young (n = 15, 25 ± 4 years) and older adults (n = 18, 71 ± 6 years) during simultaneous isometric contractions of both index fingers. Target forces ranged from 5% to 30% maximum voluntary contraction (MVC), where force variability and first dorsal interosseus activity were measured while (1) subjects viewed visual targets for both index fingers, (2) a visual target was provided for the dominant index finger only, and (3) visual targets were removed for both index fingers during bilateral isometric contractions. When subjects were provided with bilateral visual feedback during simultaneous contractions at low forces (5% and 10% MVC), older adults produced greater force variability than younger subjects (p = 0.002). However, when bilateral visual feedback was removed, age-related differences in variability were no longer present. Between-limb force variability differences existed at higher force outputs (20% and 30% MVC) when visual feedback was removed for the nondominant limb during bilateral isometric index finger abduction (p = 0.002). The control of bilateral force variability is compromised in older adults when visuomotor processes are engaged. However, age-related differences in force variability are abolished when no task-related visual feedback is available, and isometric contractions are based on internally guided feedback.
本研究观察了视觉反馈对年轻人和老年人肢体间力量变异性关系的影响。在双手食指同时进行等长收缩时,对健康的年轻人(n = 15,25±4岁)和老年人(n = 18,71±6岁)的外展力进行了检测。目标力量范围为最大自主收缩(MVC)的5%至30%,在以下三种情况下测量力量变异性和第一背侧骨间肌活动:(1)受试者观看双手食指的视觉目标;(2)仅为优势食指提供视觉目标;(3)在双侧等长收缩期间去除双手食指的视觉目标。当受试者在低力量(5%和10%MVC)同时收缩时获得双侧视觉反馈时,老年人产生的力量变异性大于年轻受试者(p = 0.002)。然而,当去除双侧视觉反馈时,变异性方面的年龄相关差异不再存在。在双侧食指等长外展过程中,当非优势肢体的视觉反馈被去除时,在较高力量输出(20%和30%MVC)时存在肢体间力量变异性差异(p = 0.002)。当涉及视觉运动过程时,老年人对双侧力量变异性的控制受到损害。然而,当没有与任务相关的视觉反馈且等长收缩基于内部引导反馈时,力量变异性方面的年龄相关差异消失。