Elsevier/North-Holland Biomedical Press COMPARISON OF THE RECRUITMENT AND DISCHARGE PROPERTIES OF MOTOR UNITS IN H U M A N BRACHIAL BICEPS AND A D D U C T O R POLLICIS D U R I N G ISOMETRIC CONTRACTIONS
Elsevier/North-Holland Biomedical Press COMPARISON OF THE RECRUITMENT AND DISCHARGE PROPERTIES OF MOTOR UNITS IN H U M A N BRACHIAL BICEPS AND A D D U C T O R POLLICIS D U R I N G ISOMETRIC CONTRACTIONS
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发表时间：
2018
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通讯作者：
C. Kukulka;H. Clamann
中科院分区：
文献类型：
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作者：
C. Kukulka;H. Clamann
实验旨在评估速率编码和运动单元募集对不同纤维组成和功能的两种肌肉产生力的相对贡献。在稳定的等长收缩过程中，在肱二头肌，一个大的近端肢体肌肉的混合纤维成分，和拇收肌，一个小的手肌肉主要由I型肌纤维，记录单个运动单位动作电位。在每个肌肉的整个力范围内获得动作电位尖峰序列。结果表明，这两块肌肉以不同的方式控制。在肱二头肌中，从0到88 ~最大自主收缩（MVC）观察到募集。在拇收肌中，在大于50 ~ MVC的力下没有观察到运动单位的募集，大多数募集发生在30 ~ MVC以下。平均而言，与肱二头肌相比，拇收肌运动单位的放电速率更高，规律性较差，且短峰间间期（间期_< 20毫秒）的出现频率更高。这些发现表明，率编码在拇收肌的力调制中起着更突出的作用，而募集在肱二头肌的整个收缩力范围内起着更重要的作用。
Experiments were designed to assess the relative contribution of rate coding and motor unit recruitment to force production in two muscles of different fiber composition and function. Single motor unit action potentials were recorded during steady isometric contraction in biceps brachii, a large proximal limb muscle of mixed fiber composition, and adductor pollicis, a small hand muscle comprised mainly of type I muscle fibers. Action potential spike trains were obtained over the entire force range in each muscle. The results suggest that these two muscles are controlled in different ways. In biceps brachii, recruitment was observed from 0 to 88 ~ maximum voluntary contraction (MVC). In adductor pollicis, no motor unit was observed to be recruited at forces greater than 50 ~ MVC, with the majority of recruitment occurring below 30 ~ MVC. On the average, motor units in adductor pollicis discharged at higher rates, with less regularity, and with a greater frequency of occurrrence of short interspike intervals (intervals _< 20 msec) than those in biceps brachii. Such findings suggest that rate coding plays a more prominent role in force modulation in adductor pollicis, while recruitment plays a more important role throughout the contractile force range in biceps brachii.