# Postural Strategies Used While Donning a Simulated xEMU Spacesuit
## 4 Discussion  
Here, we were able to determine how COG shifts, due to the xEMU Vest and HUT, affect postural strategies during gait. According to the AAD results, the xEMU Vest does not significantly affect the following four body segments: head, thorax, lumbar, and pelvis. The xEMU Vest does not significantly influence how the body segments move with each other or in space. The body segments follow the same path of motion regardless of whether the xEMU Vest is donned, but this is not the case for the HUT. The HUT significantly influences how body segments move with each other. The postural strategy employed by the participants may have been similar between unsuited and the xEMU Vest. However, the xEMU Vest does significantly impact how the body segments balance during gait. There were significant differences in both the forward- and the backward-walking trials AIs. The xEMU Vest significantly decreased the independent stability of the head and further deepened the dependability of the thorax on the lower body segment. The head and thorax body segments, in turn, started to rely on the inferior anatomical body segments to balance during gait. Previous studies with healthy adults [5] demonstrated that in healthy adults with eyes opened walking forward on hard ground, the head roll and pitch AI is just slightly above 0, meaning it does not rely on the anatomical body segment below it. We found similar results: walking forward on the hard ground surface while unsuited resulted in head roll and pitch AIs just slightly below 0. We believe this difference to be within the margin of error between the two independent studies. However, with the xEMU Vest, the pitch and yaw AI decreased significantly and made the head reliant on the thorax, the inferior anatomical body segment below it for both the walking conditions. Past studies conducted on adults and children [5,6] suggested that the head will become more independently stable, with a positive AI approaching +1, when the difficulty of equilibrium during gait is increased; this was what was observed for the HUT AIs. If increasing the difficulty in balancing during gait leads to a head AI approaching +1, then a head AI approaching -1 equates to a decrease in difficulty in balancing during gait. The xEMU Vest does not make balancing during gait more difficult, but instead it does the opposite, it makes it easier. The HUT AIs did follow the findings of previous studies in that the head increased in independent balance. However, the AIs only increased in the pitch and yaw directions, while the AI decreased in the roll. The decrease in AI, or the increased dependency on the lower body segment in the roll direction, is an indication that a different postural strategy is deployed when donning the HUT. The AAD values indicate that the outcome of the implemented postural strategy was the same with/without the xEMU Vest, but the AIs show that the postural strategies chosen by the 17 participants were indeed different. Humans are conditioned to walk in a certain way: [PERSON] and [PERSON] [6] concluded that children aged seven and above started to implement the head stabilization strategy in space. The head is stabilized independently from the body during gait. The xEMU Vest changes this and makes the head reliant on the thorax (inferior anatomical body segment) to balance in space, which is similar to what occurs in children aged 6 and under. With the participants donning the xEMU Vest, their COG shifted superior and created a \"top-heavy\" balance point. Children who are 6 years old and under also have a \"top-heavy\" balance point, or superiorly shifted COG, since children's bodies need to grow to be able to support their heads.