Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control
Brewer, Jeffrey David
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The National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. This research provides insight for maintaining the ability of astronauts to perform coordinated, bipedal locomotion activities, following transitions between gravitational acceleration fields. In addition, a unique environmental simulator has been developed which enables further research regarding the complex interactions between humans and the environments in which they move. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off-loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: (1) the environmental simulator constructed for this dissertation effort does induce locomotor adaptations following partial gravity running; (2) the precision stepping task is a sensitive test for illuminating aspects of these adaptations; and (3) musculoskeletal loading improves the locomotor adaptation process.