Differences of Fatigability in Human Skeletal Muscles

本文研究了5~7名男性肩外展肌、肘屈肌、伸肘肌、屈膝肌、伸膝肌、足底屈肌和背屈肌的等长收缩力值与达到三个肌肉疲劳指数的时间的关系。耐力任务是在最大自愿收缩(MVC)的5、10、15、20、30、40和50%的收缩水平下进行的。相对力量(F%MVC)与耐力时间或疲劳时间(“Darui”)和疼痛(“Itai”)出现时间(Tmin)的曲线符合下列方程：logT=a+Blog(F-k)，0&lt；=k&lt；=30。在耐力时间上，最拟合方程式中的常数k、a和b分别为3、2.02和-1.22，肘屈肌为0、4.33和-2.52，肘伸肌为2、3.05和-1.81，膝屈肌为0、3.05和-1.63，膝伸肌为8、1.96和-1.23，足底屈肌为0、4.53和-2.47，背屈肌为0、4.51和-2.48。疼痛出现时间：肩外展肌分别为2、1.64和-1.09，肘屈肌分别为0、3.33和-1.99，伸肘肌分别为2、2.25和-1.43，屈膝肌分别为0、2.94和-1.78，伸膝肌分别为8、1.35和-0.96，足底屈肌分别为0、3.88和-2.16，背屈肌分别为0、3.90和-2.24。在被检查的肌肉群中，肩部外展肌是最容易疲劳的。最不容易疲劳的是足底屈肌和背屈肌，其次是肘屈肌。膝关节伸肌在较高的收缩水平下是疲劳的，而在非常低的收缩水平下相对不疲劳。膝关节屈肌在较高的收缩水平时相对无疲劳性，在较低的收缩水平时变得容易疲劳，并表现出与肘部伸肌相似的疲劳性。

The relationship between force level of isometric contraction and time until three indices of muscular fatigue was studied for the shoulder abductors, elbow flexors, elbow extensors, knee flexors, knee extensors, plantar flexors and dorsiflexors in 5-7 males. Endurance tasks were performed at the contraction levels of 5, 10, 15, 20, 30, 40 and 50% of the maximal voluntary contraction (MVC). The relative force (F %MVC) versus the endurance time or the time of tiredness("darui") and pain("itai") appearance (T min) curves were fitted to the following equation; logT=a+blog(F-k), 0<=k<=30. In the endurance time the constants k, a and b in the most fitted equation were 3, 2.02 and -1.22 for the shoulder adbuctors, 0, 4.33 and -2.52 for the elbow flexors, 2, 3.05 and -1.81 for the elbow extensors, 0, 3.05 and -1.63 for the knee flexors, 8, 1.96 and -1.23 for the knee extensors, 0, 4.53 and -2.47 for the plantar flexors, and 0, 4.51 and -2.48 for the dorsiflexors, respectively. In the time of pain appearance these values were 2, 1.64 and -1.09 for the shoulder abductors, 0, 3.33 and -1.99 for the elbow flexors, 2, 2.25 and -1.43 for the elbow extensors, 0, 2.94 and -1.78 for the knee flexors, 8, 1.35 and -0.96 for the knee extensors, 0, 3.88 and -2.16 for the plantar flexors, and 0, 3.90 and -2.24 for the dorsiflexors, respectively. In the examined muscle groups, the shoulder abductors were the most fatigable. The least fatigable were the plantar flexors and dorsiflexors, followed by the elbow flexors. The knee extensors were fatigable at higher contraction levels, and relatively fatigueless at very low contraction levels. The knee flexors, which were relatively fatigueless at higher contraction levels, became fatigable at lower contraction levels, and showed similar fatigability as the elbow extensors.