Del Valle Alejandro, Thomas Christine K
Department of Neurological Surgery, The Miami Project to Cure Paralysis, Lois Pope Life Center, 1095 NW 14th Terrace (R-48), PO Box 016960, Miami, FL 33136, USA.
Can J Physiol Pharmacol. 2004 Aug-Sep;82(8-9):769-76. doi: 10.1139/y04-084.
Firing rates of motor units and surface EMG were measured from the triceps brachii muscles of able-bodied subjects during brief submaximal and maximal isometric voluntary contractions made at 5 elbow joint angles that covered the entire physiological range of muscle lengths. Muscle activation at the longest, midlength, and shortest muscle lengths, measured by twitch occlusion, averaged 98%, 97%, and 93% respectively, with each subject able to achieve complete activation during some contractions. As expected, the strongest contractions were recorded at 90 degrees of elbow flexion. Mean motor unit firing rates and surface EMG increased with contraction intensity at each muscle length. For any given absolute contraction intensity, motor unit firing rates varied when muscle length was changed. However, mean motor unit firing rates were independent of muscle length when contractions were compared with the intensity of the maximal voluntary contraction (MVC) achieved at each joint angle.
在覆盖肌肉长度整个生理范围的5个肘关节角度进行短暂的次最大和最大等长自主收缩期间，测量了健全受试者肱三头肌的运动单位放电频率和表面肌电图。通过抽搐阻滞测量，在最长、中等长度和最短肌肉长度时的肌肉激活率分别平均为98%、97%和93%，每个受试者在某些收缩过程中能够实现完全激活。正如预期的那样，在肘关节屈曲90度时记录到最强的收缩。在每个肌肉长度下，平均运动单位放电频率和表面肌电图随收缩强度增加。对于任何给定的绝对收缩强度，当肌肉长度改变时，运动单位放电频率会发生变化。然而，当将收缩与在每个关节角度实现的最大自主收缩（MVC）强度进行比较时，平均运动单位放电频率与肌肉长度无关。
