title: Joint loading in the lower extremities during elliptical exercise.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Institute of Biomedical Engineering, School of Occupational Therapy, National Taiwan University, Taiwan. twlu@ntu.edu.tw
authors.forename: Tung-Wu
authors.initials: TW
authors.lastname: Lu
authors.forename: Hui-Lien
authors.initials: HL
authors.lastname: Chien
authors.forename: Hao-Ling
authors.initials: HL
authors.lastname: Chen
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000295:instrumentation*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D035002:Lower Extremity / Q000293:injuries*; D008297:Male; D010807:Physical Endurance / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D013624:Taiwan; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D014947:Wounds and Injuries / Q000517:prevention & control / Q000534:rehabilitation*