Background Clinical tests for detecting central and peripheral shoulder fatigue are limited. The discrimination of these two types of fatigue is necessary to better adapt recovery intervention. The Kinematic Theory of Rapid Human Movements describes the neuromotor impulse response using lognormal functions and has many applications in pathology detection. The ideal motor control is modeled and a change in the neuromuscular system is reflected in parameters extracted according to this theory. Objective The objective of this study was to assess whether a shoulder neuromuscular fatigue could be detected through parameters describing the theory, if there is the possibility to discriminate central from peripheral fatigue, and which handwriting test gives the most relevant information on fatigue. Methods Twenty healthy participants performed two sessions of fast stroke handwriting on a tablet, before and after a shoulder fatigue. The fatigue was in internal rotation for one session and in external rotation during the other session. The drawings consisted of simple strokes, triangles, horizontal, and vertical oscillations. Parameters of these strokes were extracted according to the Sigma–Lognormal model of the Kinematic Theory. The evolution of each participant was analyzed through a U-Mann–Whitney test for individual comparisons. A Hotelling’s T2-test and a U-Mann–Whitney test were also performed on all participants to assess the group evolution after fatigue. Moreover, a correlation among parameters was calculated through Spearman coefficients to assess intrinsic parameters properties of each handwriting test. Results Central and peripheral parameters were statistically different before and after fatigue with a possibility to discriminate them. Participants had various responses to fatigue. However, when considering the group, parameters related to the motor program execution showed significant increase in the handwriting tests after shoulder fatigue. The test of simple strokes permits to know more specifically where the fatigue comes from, whereas the oscillations tests were the most sensitive to fatigue. Conclusion The results of this study suggest that the Sigma–Lognormal model of the Kinematic Theory is an innovative approach for fatigue detection with discrimination between the central and peripheral systems. Overall, there is a possibility to implement the setting for clinics and sports personalized follow-up.

中文翻译：

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使用 Sigma-Lognormal 模型进行中枢和外周肩部疲劳预筛查：概念验证

背景 用于检测中枢和外周肩部疲劳的临床试验是有限的。区分这两种类型的疲劳对于更好地适应恢复干预是必要的。快速人体运动的运动学理论描述了使用对数正态函数的神经运动脉冲响应，并在病理学检测中具有许多应用。理想的运动控制被建模，神经肌肉系统的变化反映在根据该理论提取的参数中。目的 本研究的目的是评估是否可以通过描述理论的参数检测肩部神经肌肉疲劳，是否有可能区分中枢疲劳和外周疲劳，以及哪种笔迹测试提供了与疲劳最相关的信息。方法 20 名健康参与者在肩部疲劳之前和之后在平板电脑上进行了两次快速笔迹书写。疲劳在一个会话中处于内旋状态，在另一会话中处于外旋状态。图纸由简单的笔划、三角形、水平和垂直振荡组成。这些笔画的参数是根据运动学理论的 Sigma-Lognormal 模型提取的。通过 U-Mann-Whitney 检验分析每个参与者的演变，以进行个体比较。还对所有参与者进行了霍特林 T2 测试和 U-Mann-Whitney 测试，以评估疲劳后的群体演变。此外，通过斯皮尔曼系数计算参数之间的相关性，以评估每个笔迹测试的内在参数特性。结果 疲劳前后中枢和外周参数在统计学上存在差异，有可能对其进行区分。参与者对疲劳有不同的反应。然而，在考虑该组时，与运动程序执行相关的参数显示，肩部疲劳后的手写测试显着增加。简单的笔画测试可以更具体地了解疲劳的来源，而振动测试对疲劳最敏感。结论 这项研究的结果表明，运动学理论的 Sigma-Lognormal 模型是一种创新的疲劳检测方法，可区分中央系统和外围系统。总体而言，有可能实施诊所和运动个性化随访的设置。