The Mk-7 Gravity Loading Countermeasure Skinsuit: Evaluation of Insole Pressure and Load Distribution

The Gravity Loading Countermeasure Skinsuit (GLCS or “Skinsuit”) is an intravehicular activity suit for astronauts that simulates the effects of Earth’s gravity to combat muscle atrophy and spinal elongation through the application of axial load on the body using material tension. Currently, the Mark (Mk)-7 GLCS provides approximately 30% bodyweight loading, and a quantitative analysis was performed to understand and characterize the loading profiles. In this study, the pressure distributed across the insole was analyzed during locomotion in suited and unsuited conditions. The spatial load distribution over the sole of the foot was measured to identify any over- or under-pressurization compared to typical 1 g insole loading, which provides crucial sensorimotor feedback to foot mechanoreceptors. A pilot study was conducted on one participant wearing the Skinsuit on the Moonwalker, a partial gravity simulator, to investigate the load generated by the GLCS while running for 60-second intervals in 0.17 g, 0.38 g, and 1 g. An insole pressure-sensing system measured insole pressure distribution across multiple gait cycles, separated by heel strikes. To examine foot profile loading, pressure on the toes, metatarsals, midfoot, and heel were extracted from recorded insole data measurements. While this study is limited to one participant, the initial results show that the GLCS increases insole loading compared to unsuited conditions, supporting the goal of reloading the body towards 1 g loading conditions. The results of this study assess the Skinsuit’s ability to return some load onto the participant when experiencing differing partial gravities and determine how close the GLCS is to approaching a load equivalent to Earth’s gravity.