The dependence of force enhancement on activation in human adductor pollicis
The dependence of force enhancement on activation in human adductor pollicis
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人类拇内收肌的力量增强对激活的依赖性
DOI：
10.1007/s00421-006-0170-4
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发表时间：
2006
影响因子：
3
通讯作者：
W. Herzog
中科院分区：
文献类型：
--
作者：
Ali E Oskouei;W. Herzog
人们已经充分认识到，主动肌肉/纤维拉伸后的稳态等长力大于电刺激肌肉和最大随意收缩（MVC）的相应等长力。然而，最近获得的证据表明，子MVC的力增强性能是从电诱导和MVC观察到的不同。具体来说，它似乎是力增强激活依赖，并有一个特定的主题阈值的力增强在子MVC。为了解决这些建议，在拉伸过程中的力量增强和自愿激活之间的关系进行了调查，在11名健康受试者。研究了人类拇收肌，并测量了力量增强，同时将稳态等长阶段期间的肌肉激活控制在MVC的30%的水平。为了研究激活对力增强的影响，受试者在0，10，30，60和100%的最大自愿努力进行拉伸收缩，而在所有情况下，在30%的激活获得的拉伸后的稳态等长力，进行了比较，在等长参考收缩中测量的相应值。如果被动进行肌肉拉伸，则不会出现力量增强，但当肌肉拉伸以最大自愿努力进行时，所有受试者都表现出力量增强。当在拉伸阶段增加激活水平时，力量增强增加，表现出力量增强的受试者数量也增加。我们从这些结果中得出结论，自愿收缩过程中的力增强是激活依赖的阈值是受试者特异性的。
It has been well recognized that the steady-state isometric force after active muscle/fiber stretch is greater than the corresponding isometric force for electrically stimulated muscles and maximal voluntary contractions (MVC). However, recent evidence obtained for sub-MVC suggests that force enhancement properties are different from those observed for electrically induced and MVC. Specifically, it appears that force enhancement is activation-dependent and that there is a subject-specific threshold for force enhancement in sub-MVC. To address these suggestions, the relationship between force enhancement and voluntary activation during stretch was investigated in 11 healthy subjects. Human adductor pollicis muscles were studied and force enhancement was measured while muscle activation during the steady-state isometric phase was controlled at a level of 30% of MVC. In order to study the effects of activation on force enhancement, subjects performed stretch contractions at 0, 10, 30, 60, and 100% of maximal voluntary effort while the steady-state isometric force after stretch, obtained at 30% of activation in all cases, was compared to the corresponding values measured in the isometric reference contractions. There was no force enhancement if muscle stretching occurred passively but all subjects showed force enhancement when muscle stretching occurred at maximal voluntary effort. When increasing the level of activation during the stretch phase, force enhancement increased, and the number of subjects who showed force enhancement increased as well. We conclude from these results that force enhancement during voluntary contractions is activation-dependent with a threshold that is subject-specific.