The gravity loading countermeasure skinsuit : a passive countermeasure garment for preventing musculoskeletal deconditioning during long-duration spaceflight

Abstract

One of the hallmarks of long-duration spaceflight is physiological deconditioning seen in the absence of gravity. Negative changes in bone, muscle, and other physiological systems occur rapidly in space, and have the potential to severely limit the human space exploration program. The deficits in bone are mostly seen in the weight-bearing areas of the skeleton, highlighting the influence of gravity. Current countermeasures employed on the International Space Station are vastly improved over previous countermeasures equipment, however, with long duration exploration missions, there is a need to optimize countermeasures to adequately combat these physiological changes. One countermeasure concept that may aid in helping prevent deconditioning is the Gravity Loading Countermeasure Skinsuit, which uses elastic materials to provide bodyweight loading similar to that seen in the presence of gravity via compression along the cephalocaudal (head to toe) axis of the body. Preliminary work performed in our lab produced prototype garments that were characterized for comfort and wearability, but had design deficiencies that prevented them from providing full bodyweight loading to the subjects. In order to create an effective countermeasure garment we first developed a model of suit-body interactions through computational simulations to inform suit design. We then built and characterized prototype suits, and evaluated the potential of the suit for efficacy in ameliorating musculoskeletal deconditioning in earth-based analogs of unloading. Modeling efforts showed that the GLCS could provide bodyweight-like loading to the subjects in simulated microgravity, and in some cases provided higher loads to the muscles and joints than those seen during unsuited movements in Earth gravity. Prototype suits were constructed that provided 76-84% bodyweight loading to the subjects. During exercise testing on a vertical treadmill, the subjects were able to run and walk normally, and the suit was shown to increase physiological workload, as well as joint and muscle loading, during running in simulated microgravity.