Transformational mechanism(s) of neuromuscular activation and performance in human development

影响肌肉力量和力量的因素很多。拟议的研究计划侧重于神经生理因素，总体目标是建立对肌肉功能控制机制和影响它们的因素的全面了解。我们将使用一种独特的方法来检查外周、中枢和荷尔蒙因素，这是由儿童成人过渡模型所强调的，根据该模型，已知的生理和功能肌肉变化与已知的肌肉激活变化相关。 人类的成熟，尤其是青春期，涉及到广泛的变化。大小标准化的肌肉力量、速度和力量显著增加，而运动单位(MU)的利用和肌肉成分的性质似乎也发生了变化。了解决定MU激活的因素是了解肌肉功能控制和神经运动发育的核心，并将通过儿童-成人过渡模型进行检验。 在接下来的5年里，我们将研究MU激活的外周和中枢指标以及它们在成熟过程中的相互关系。这些指标将通过传统的表面肌电信号(EMG)以及最近开发的技术进行检查，该技术允许同时对多个EMG信号进行空间和时间分解。这种非侵入性的技术，在伦理上适合儿童，允许在肌肉收缩期间识别单个MU，因此，允许表征不同的MU组和激活模式。我们将探索这些模式，以及已知的MU激活的外围指标，如激活缺陷和高阈值MU招募开始，在儿童和成人中，无论性别。在儿童-成人过渡期，这些指标的相互关系的变化将阐明影响肌肉功能的外周因素和中枢因素的相对贡献。 由于荷尔蒙变化是儿童-成人过渡期的特征，并已被证明对许多成熟和性相关的功能变化负有责任，因此荷尔蒙效应(主要是性激素)也将作为肌肉激活及其控制的可能决定因素进行调查。 最后，将调查外部干预措施的潜力，例如特定形式的体育训练，以影响肌肉激活能力(例如，激活缺陷，启动更高阈值的MU招募)，以阐明相关的控制机制。 这项工作对于理解肌肉功能和代谢特征变化的基本机制非常重要，并将为了解神经运动发育的基本性质提供新的见解。由于大多数儿科调理和康复计划都是基于成人的数据，我们的工作也将为增强神经肌肉功能的适合年龄的策略提供信息。

Many factors affect muscular force and power. The proposed research program focuses on neurophysiological factors with the overall goal of establishing a comprehensive understanding of muscle functional control mechanisms and factors affecting them. We will examine peripheral, central and hormonal factors using a unique approach highlighted by the childadult transition model, whereby known physiologic and functional muscular changes are associated with known muscle activation changes. Human maturation, particularly the pubertal period, involves wide-ranging changes. Size-normalized muscle force, speed, and power increase dramatically, while the nature of motor-unit (MU) utilization and muscle composition, also appear to change. Understanding the factors determining MU activation is central to understanding muscle functional control and neuromotor development and will be examined through the child-adult transition model. During the next 5 years, we will study peripheral and central indicators of MU activation and their inter-relationship during maturation. These indicators will be examined via traditional surface electromyography (EMG) as well as by the recently-developed technology allowing for the spatial and temporal decomposition of multiple simultaneous EMG signals. This non-invasive technique, ethically suitable for children, allows for identification of individual MUs during muscle contraction and thus, allows for characterization of distinct MU groups and activation patterns. We will explore those patterns, along with known peripheral indicators of MU activation, such as activation deficit and high-threshold MU recruitment onset, in children and adults of both sexes. Changes in the inter-relationship of these indicators, during the childadult transition period, will shed light on the relative contribution of peripheral vs. central factors affecting muscle function. Since hormonal changes characterize the childadult transition period and have been shown responsible for numerous maturational- and sex-related functional changes, hormonal effects (mainly, sex hormones) will also be investigated as possible determinants of muscle activation and its control. Finally, the potential of external interventions, such as specific forms of physical training, to affect muscle activation capacity (e.g., activation deficit, onset of higher-threshold MU recruitment) will be investigated to shed light on the involved control mechanisms. This work is important for understanding the fundamental mechanisms underlying changes in muscle functional and metabolic characteristics, and will provide novel insights into the fundamental nature of neuromotor development. Since most pediatric conditioning and rehabilitation programs are based on adult-originated data, our work will also inform age-appropriate strategies to enhance neuromuscular function.