Lu Tung-Wu, Chien Hui-Lien, Chen Hao-Ling
Institute of Biomedical Engineering, School of Occupational Therapy, National Taiwan University, Taiwan.
Med Sci Sports Exerc. 2007 Sep;39(9):1651-8. doi: 10.1249/mss.0b013e3180dc9970.
To determine the joint loading during elliptical exercise (EE) by a detailed three-dimensional dynamic analysis, and to compare the results with those during level walking.
Fifteen male adults performed level walking and EE while 3D kinematic data, right pedal reaction forces (PRF), and ground reaction forces (GRF) were measured. Pedal rate (cadence) and step length during EE without workload were set according to those measured during level walking for each subject. The motion of the body's center of mass, lower-limb-joint angles and moments were obtained.
Pedal rates and step lengths were 52.20 rpm (SD=2.34) and 50.56 cm (SD=2.14), respectively. During early stance the vertical PRF was smaller than the GRF, and the medial and posterior shear components were greater. PRF also occurred during swing. Loading rates around heelstrike during EE were all smaller than those during walking. During EE, the peak flexion angles of the hip, knee and ankle were greater. Peak hip flexor and knee extensor moments were also greater, whereas peak ankle plantarflexor moments and all abductor moments were smaller.
Different lower-limb kinematics and kinetics were found between EE and level walking. Smaller vertical PRF and loading rates during EE were achieved at the expense of greater hip flexor and knee extensor moments. Use of the elliptical trainer for athletic and rehabilitative training would have to consider users' joint function and muscle strength, especially at the knee, to avoid injuries.
通过详细的三维动态分析确定椭圆运动（EE）过程中的关节负荷，并将结果与平地上行走时的结果进行比较。
15名成年男性进行平地上行走和椭圆运动，同时测量三维运动学数据、右踏板反作用力（PRF）和地面反作用力（GRF）。根据每个受试者在平地上行走时测得的踏板频率（步频）和步长，设定无负荷椭圆运动时的踏板频率和步长。获得身体重心的运动、下肢关节角度和力矩。
踏板频率和步长分别为52.20转/分钟（标准差=2.34）和50.56厘米（标准差=2.14）。在初始站立阶段，垂直PRF小于GRF，内侧和后侧剪切分量更大。摆动阶段也会出现PRF。椭圆运动过程中足跟触地时的负荷率均小于行走时。在椭圆运动过程中，髋、膝和踝关节的最大屈曲角度更大。髋部屈肌和膝部伸肌的最大力矩也更大，而踝关节跖屈肌的最大力矩和所有外展肌力矩均较小。
椭圆运动和平地行走之间存在不同的下肢运动学和动力学特征。椭圆运动过程中垂直PRF和负荷率较小，但代价是髋部屈肌和膝部伸肌力矩更大。使用椭圆训练机进行运动和康复训练时，必须考虑使用者的关节功能和肌肉力量，尤其是膝关节，以避免受伤。
