Dynamic creep and pre-conditioning of the Achilles tendon in-vivo
Dynamic creep and pre-conditioning of the Achilles tendon in-vivo
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DOI：
10.1016/j.jbiomech.2009.08.023
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发表时间：
2009-12-11
影响因子：
2.4
通讯作者：
Dunning, Russell
中科院分区：
文献类型：
--
作者：
Hawkins, David;Lum, Corey;Dunning, Russell
热身运动通常在剧烈运动之前被提倡，但热身持续时间和对肌肉-肌腱行为的影响没有很好的定义。对18名受试者的腓肠肌-跟腱复合体进行了研究，以量化跟腱在体内的动态蠕变反应，以及跟腱达到稳态行为所需的热身剂量。一个定制的测试室被用来确定每个受试者在等长脚踝足底屈曲努力时的最大自愿收缩(MVC)。受试者的右膝和脚踝被固定了一个小时。然后，受试者在0.75赫兹的频率下进行超过7分钟的循环等长踝关节足底屈曲，相当于他们MVC的25%-35%。在每一分钟的连续活动开始时，采集踝部足底屈曲力和位于腓肠肌-跟腱和跟骨-跟腱交界处的双超声探头的图像，时间为8秒。超声图像分析以量化25%MVC力(epsilon(25%MVC))每分钟的平均相对跟腱应变。Ep(25%MVC)从活动开始时的0.3%增加到7分钟后的3.3%，总的动态蠕变接近3.0%。Epsilon(25%MVC)在前5分钟以每分钟0.56%的速度增加，此后每分钟增加不到0.13%。因此，在一段时间的不活动之后，跟腱需要持续至少6分钟的低强度热身或产生270个负荷循环才能达到相对稳定的行为。(C)2009爱思唯尔有限公司。保留所有权利。
Warm-up exercises are often advocated prior to strenuous exercise, but the warm-up duration and effect on muscle-tendon behavior are not well defined. The gastrocnemus-Achilles tendon complexes of 18 subjects were studied to quantify the dynamic creep response of the Achilles tendon in-vivo and the warm-up dose required for the Achilles tendon to achieve steady-state behavior. A custom testing chamber was used to determine each subject's maximum voluntary contraction (MVC) during an isometric ankle plantar flexion effort. The Subject's right knee and ankle were immobilized for one hour. Subjects then performed over seven minutes of cyclic isometric ankle plantar flexion efforts equal to 25-35% of their MVC at a frequency of 0.75 Hz. Ankle plantar flexion effort and images from dual ultrasound probes located over the gastrocnemius muscle-Achilles tendon and the calcaneus-Achilles tendon junction were acquired for eight seconds at the start of each sequential minute of the activity. Ultrasound images were analyzed to quantify the average relative Achilles tendon strain at 25% MVC force (epsilon(25%MVC)) for each minute. The epsilon(25%MVC) increased from 0.3% at the start of activity to 3.3% after seven minutes, giving a total dynamic creep of similar to 3.0%. The epsilon(25%MVC) increased by move than 0.56% per minute for the first five minutes and increased by less than 0.13% per Minute thereafter. Therefore, following a period of inactivity, a low intensity warm-up lasting at least six minutes or producing 270 loading cycles is required for an Achilles tendon to reach a relatively steady-state behavior. (C) 2009 Elsevier Ltd. All rights reserved.