Spinal Network Adaptability for the Control of Steady Contractions in Men and Women

随着年龄的增长，我们的功能性运动能力下降。然而，这种下降在女性中比在男性中更为明显。在接下来的5年里，将进行研究，通过举起和放下一杯饮料的任务来模拟功能运动，并通过年轻（18-25岁）和老年（50 - 75岁）男性和女性肘关节屈肌的力量或加速度变化来测量控制。调节肱二头肌运动神经元输出的脊髓输入将在功能性运动的力控制评估中被量化。肱二头肌是研究运动神经元活动的微小变化如何影响力量产生的理想场所，尤其是对功能性运动至关重要的前臂控制。实验将使用表面肌电图和留置肌电图（EMG）来测量特定肌肉和运动单元的活动，这些肌肉和运动单元调节稳定收缩的产生。通过一系列的研究，我们将首次量化功能性运动中单个运动单元的活动，以及反射反馈是如何整合和改变与产生稳定收缩相关的脊髓运动神经元输出的。这项研究将产生关于人类脊髓网络的基础知识，这些神经网络共同促进运动神经元输出调节功能运动。这项研究具有重要意义，因为确定与运动神经元输出相关的脊柱整合对于理解神经肌肉系统的可塑性是必要的，可塑性有助于性别特异性年龄相关的功能性运动衰退。与先前的调查一致，该研究计划将为大约20名高素质人员提供高级培训，使神经生理学的技术技能发展适用于基本人体运动科学的科学发现。

As we age, our functional movement declines. However, this decline is more pronounced in women than in men. Over the next 5 years, studies will be conducted where functional movement is modeled through the task of lifting and lowering a cup for drinking and control is measured through variability in force or acceleration of the elbow flexors in young (18-25 y) and old (>75 y) men and women. Spinal inputs that modulate motoneuron output in the biceps brachii will be quantified in the evaluation of force control in the functional movement. The biceps brachii muscle, through distinct anatomical and physiological compartments of the short and long head is ideal for studying how small changes in motoneuron activity impacts force production, especially forearm control that is central to functional movement. Experiments will use surface and indwelling electromyography (EMG) to measure the activity of specific muscles and motor units that regulate the production of steady contractions. Through a series of investigations we will be the first to quantify single motor unit activity during functional movement and how reflex feedback is integrated and alters spinal motoneuron output relevant to producing steady contractions in young and old men and women. This research will generate fundamental knowledge about spinal networks in humans that collectively contribute to motoneuron output in the regulation of functional movement. This research is significant as determination of spinal integration relative to motoneuron output is necessary for understanding the plasticity in the neuromuscular system that contributes to sex-specific age-related decline of functional movement. Consistent with prior investigations, this research program will result in advanced training for approximately 20 highly qualified personnel enabling technical skill development in neurophysiology applicable to scientific discovery in basic human movement science.