Effect of Load Levels of Subject Loading Device on Gait, Ground Reaction Force, and Kinematics during Human Treadmill Locomotion in a Weightless Environment

摘要

Prolonged exposure to weightlessness associated with spaceflight provokes profound physiological changes in humans. Two areas of significant concern are bone loss and neuromuscular deconditioning. Changes in lower-limb neuromuscular activation patterns have raised concern about the ability of astronauts to escape from their spacecraft in an emergency landing situation. Countermeasures that stimulate bone maintenance and locomotor control are vital to the success of human spaceflight. It has been hypothesized that, to help maintain the bone mineral density that an astronaut has in normal gravity, the ground reaction force (GRF) achieved during locomotion in weightlessness should mimic the GRF that occurs on Earth. Currently, a crewmember exercising on the treadmill recieves an external load by means of an upper-body harness that attaches to the SLD via extender straps or bungees. GRF is imparted as the SLD pulls the crewmember toward the treadmill surface during locomotion. The primary objective of this investigation was to determine if gait, GRF, an kinematics during locomotion at 0G, using a simulated ISS treadmill and SLD, are significantly different from those found during locomotion at 1G. The secondary objective of this investigation was to quantify the load magnitude, variability, and stiffness of the external load applied to the crewmember by the SLD during locomotion at -G.