Yoshioka Shinsuke, Nagano Akinori, Himeno Ryutaro, Fukashiro Senshi
Department of Life Sciences (Sports Sciences), University of Tokyo, Japan.
Biomed Eng Online. 2007 Jul 3;6:26. doi: 10.1186/1475-925X-6-26.
A sit-to-stand (STS) movement requires muscle strength higher than that of other daily activities. There are many elderly people, who experience difficulty when standing up from a chair. The muscle strength required (or the load on the joints) during a STS task is determined by the kinematics (movement pattern). The purpose of this study was to evaluate the kinematics and resultant joint moments of people standing up from a chair in order to determine the minimum peak joint moments required for a STS task.
This study consisted of three steps. In the first step, kinematic data of lower extremity joint angles (hip, knee and ankle) during STS movements were experimentally collected from human subjects. Eighty-five sets of STS kinematic data were obtained. In the second step, the experimentally collected kinematic data and a link segment model of the human body were used to generate more than 5,000,000 computed STS movements. In the third step, using inverse dynamics method, joint moments of the lower extremity were calculated for all movements obtained through the preceding steps. From the outputs of the third step, the optimal kinematics (movement pattern) in terms of minimized peak joint moment for the hip, knee and ankle was determined.
The peak hip joint moment ranged from 0.24 to 1.92 N.m/kg. The peak knee joint moment ranged from 0.51 to 1.97 N.m/kg, and the peak ankle joint moment ranged from -0.11 to 1.32 N.m/kg. The optimal movement patterns differed depending on which minimized joint moment index was selected (hip, knee or ankle). However, the sum of the peak hip joint moment and peak knee joint moment was always approximately 1.53 N.m/kg regardless of which minimized joint moment index was selected.
The most important finding of this study was that the relation between the peak joint moments at the hip and knee joints was complementary and the sum of those moments needed to be greater than 1.53 N.m/kg in order to perform a successful STS. A combined hip-knee value of 1.5 N.m/kg or lower may indicate the need for physical rehabilitation and/or exercise to increase muscular force.
从坐到站（STS）的动作所需肌肉力量高于其他日常活动。有许多老年人在从椅子上站起来时会遇到困难。STS任务期间所需的肌肉力量（或关节上的负荷）由运动学（运动模式）决定。本研究的目的是评估从椅子上站起来的人的运动学和合成关节力矩，以确定STS任务所需的最小峰值关节力矩。
本研究包括三个步骤。第一步，通过实验收集人类受试者在STS动作过程中下肢关节角度（髋、膝和踝）的运动学数据。获得了85组STS运动学数据。第二步，将实验收集的运动学数据和人体环节模型用于生成超过500万个计算得到的STS动作。第三步，使用逆动力学方法，为通过前几步获得的所有动作计算下肢的关节力矩。从第三步的输出结果中，确定了髋、膝和踝在最小化峰值关节力矩方面的最佳运动学（运动模式）。
髋部峰值关节力矩范围为0.24至1.92N·m/kg。膝部峰值关节力矩范围为0.51至1.97N·m/kg，踝部峰值关节力矩范围为-0.11至1.32N·m/kg。最佳运动模式因选择的最小化关节力矩指标（髋、膝或踝）而异。然而，无论选择哪个最小化关节力矩指标，髋部峰值关节力矩和膝部峰值关节力矩之和始终约为1.53N·m/kg。
本研究最重要的发现是，髋膝关节的峰值关节力矩之间的关系是互补的，为了成功完成STS动作，这些力矩之和需要大于1.53N·m/kg。髋膝联合值为1.5N·m/kg或更低可能表明需要进行身体康复和/或锻炼以增加肌肉力量。
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