The primary purpose of this investigation was to determine the similarities and differences between locomotion on the eZLS, in microgravity, and in normal gravity. The secondary purpose was to determine how the external load (EL) mechanism affected locomotion on the eZLS. The results of this investigation will help to determine how accurately locomotion in microgravity is replicated on the eZLS, and the important external loading mechanism characteristics that affect locomotion on the eZLS. Two hypotheses were tested during this investigation: (1) When walking and running (controlling for static external load magnitude), locomotion kinematics, ground reaction force (GRF), and lower extremity muscle activation patterns will differ between eZLS and microgravity environments. (2) When walking and running on the eZLS (controlling for static external load magnitude), locomotion kinematics, GRF, and lower extremity muscle activation patterns will differ between external load delivered by bungees and a linear motor subject loading device (LM-SLD).
Subjects attained greater amounts of hip flexion during walking and running in microgravity. During running, subjects had greater hip range of motion. Trunk motion was significantly less on the eZLS than in microgravity. Peak impact forces, loading rate, and impulse were greater on the eZLS than in microgravity during walking with a low EL and running with a high EL. Activation timing differences existed between locations in all muscles except for the rectus femoris. The tibialis anterior and gluteus maximus were active for longer durations on the eZLS than in microgravity during walking. GRFs were greater with the LM-SLD than with bungees during eZLS locomotion.
Discussion and Operational Relevance:
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