A Rigid Body Database On Human Movement

通过研究净关节力矩和个人肌肉力量如何有助于控制人类的运动，我们打算将身体残疾人士的能力与他或她执行日常生活活动的能力联系起来。测量这些贡献对于确定自适应运动控制策略、了解选择和实施行走、站立和从坐姿站起等活动的运动控制策略的过程以及确定辅助技术在增强功能方面所起的作用至关重要。我们扩展了现有的运动分析方法，这些方法估计关节力矩或肌肉力对单个关节和身体部分的运动的影响，以及它们对整体任务性能的贡献。 早期确定净肌肉关节力矩和单个肌力对人体运动控制的贡献的努力受到以下假设的限制：肌肉努力对运动控制的相对贡献与身体部分的位置无关。运动方程的广义坐标公式表明，这一假设是不正确的，并可能导致解释人体运动分析数据的错误。我们过去的研究表明，正常步态中前进速度的产生主要来自踝关节足底屈肌的推离，而不是通过受控的下落。我们发现，踝关节足底屈肌群在同一肌群的偏心动作期间会产生上半身的向前加速。我们考察了下肢关节力矩对保持直立姿势(支撑)的相对贡献，发现在单肢支撑阶段，踝关节力矩对支撑的贡献最大。我们还检查了关节加速度对平足步态阶段关节力矩的相对敏感度，发现踝关节、膝关节和髋关节加速度对膝关节产生的力矩的敏感度几乎是对任何其他下肢关节力矩的敏感度的两倍。在步态的后跟离开阶段，踝关节和髋关节的加速度敏感度随着各自关节处的力矩的增加而增加。从这些数据可以清楚地看出，在控制站立肢体的运动方面存在显著的冗余。该模型在患有严重肌肉无力的患者中的应用表明，他们可以利用这种冗余来开发步态和坐立运动中的各种替代运动控制策略，以补偿肌肉功能的薄弱或丧失。我们进一步扩展了这些分析中使用的模型，以估计节段之间的机械能量交换的来源，并使用它来确定在步态过程中负责节间机械能量转移的肌群。我们发现，能量传递依赖于关节力矩的符号，而不是关节功率的符号，并且在正常步态中，成对的净关节力矩组合起到平衡腿部和躯干部分的能量流动的作用。

By studying how net joint moments and individual muscle forces contribute to the control of human movement, we intend to link the capabilities of a physically challenged person to his or her ability to perform activities of daily living. Measuring these contributions is critical for defining adaptive movement control strategies, understanding the process by which movement control strategies for activities like walking, standing and rising from a seated position are selected and implemented, and determining the contribution that assistive technologies play in enhancing function. We have extended existing movement analysis methodologies that estimate the influence of joint moments or muscle forces on the motion of individual joints and body segments, as well as their contribution to overall task performance. Earlier efforts to determine the contribution of net muscular joint moments and individual muscle forces to human movement control have been limited by the assumption that the relative contribution of muscular effort to the control of movement is independent of the position of the body segments. A generalized coordinate formulation of the equations of motion shows that this assumption is incorrect and can lead to errors in interpreting human movement analysis data. Our past research revealed that the generation of forward velocity during normal gait arises primarily from ankle joint plantar flexor push-off, rather than through a controlled fall. We found that the ankle joint plantar flexor muscle group produces forward acceleration of the upper body during periods in which the same muscle group acts eccentrically. We examined the relative contribution of the lower extremity joint moments to the maintenance of upright posture (support) and found that, during the single limb support phase, ankle moments generate the greatest contribution to support. We also examined the relative sensitivity of the joint accelerations to the joint moments during the foot-flat phase of gait and found that the ankle, knee and hip joint accelerations are almost twice as sensitive to moments generated at the knee than to the moments at any other lower extremity joint. During the heel-off phase of gait, the acceleration sensitivities at both the ankle and hip joints increase in response to moments at their own joint. It is clear from these data that there is significant redundancy in controlling the motion of the stance limb. Application of the model to patients with severe muscle weakness has shown how they can exploit this redundancy to develop a variety of alternative movement control strategies during gait and sit-to-stand movements to compensate for weak or lost muscle function. We have further extended the model used in these analyses to estimate the sources of mechanical energy exchange between segments, and have used it to determine the muscle groups responsible for the inter-segment transfer of mechanical energy during gait. We found that the energy transfer depends on the sign of the joint moment, rather than on the sign of the joint power, and that pairs of net joint moments function in combination to balance energy flow through the leg and trunk segments during normal gait.