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。拟建的研究项目以神经生理因素为重点，总体目标是建立对肌肉功能控制机制及其影响因素的全面了解。我们将使用儿童-成人过渡模型强调的独特方法来检查外周，中枢和激素因素，其中已知的生理和功能性肌肉变化与已知的肌肉激活变化相关。人的成熟，特别是青春期，涉及广泛的变化。尺寸标准化的肌肉力量、速度和力量急剧增加，同时运动单元（MU）利用的性质和肌肉成分也发生了变化。了解决定MU激活的因素对于理解肌肉功能控制和神经运动发育至关重要，并将通过儿童-成人过渡模型进行检验。在接下来的5年中，我们将研究成熟过程中MU激活的外周和中枢指标及其相互关系。这些指标将通过传统的表面肌电图（EMG）以及最近开发的技术进行检查，该技术允许对多个同时发生的EMG信号进行空间和时间分解。这种非侵入性技术在伦理上适用于儿童，可以在肌肉收缩过程中识别单个MU，从而可以表征不同的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募集的开始，在儿童和成人中都是如此。在儿童-成人过渡期间，这些指标相互关系的变化将揭示影响肌肉功能的外围因素和中枢因素的相对贡献。由于激素变化是儿童-成人过渡期的特征，并已被证明对许多成熟和性别相关的功能变化负责，激素效应（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研究。最后，外部干预的潜力，如特定形式的体育训练，影响肌肉激活能力（例如，激活缺陷，高阈值MU招募的开始）将被调查，以阐明所涉及的控制机制。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，并将为神经运动发育的基本性质提供新的见解。由于大多数儿童调节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龄策略提供信息。

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 child-adult 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 child-adult transition period, will shed light on the relative contribution of peripheral vs. central factors affecting muscle function. Since hormonal changes characterize the child-adult 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.