UC San Diego

Spaceflight Associated Neuro-ocular Syndrome, bone decalcification, and muscle atrophy are among the most prevalent risks associated with long-duration spaceflight. Implementing the lower body negative pressure (LBNP) technique is a potential countermeasure for these risks. LBNP counteracts head-ward fluid shifts and generates ground-reaction forces (GRFs). GRFs are beneficial for maintaining bones and muscles by generating gravitational-like loads we experience on Earth. Currently, LBNP devices are large/bulky and require the subject to maintain a stationary position. However, the mobile Gravity Suit I designed is relatively small, untethered, and flexible. It is hypothesized that by designing and developing a mobile Gravity Suit, we can generate greater GRFs than an LBNP chamber. Static LBNP chambers achieve only one GRF on the subject. This can be expressed as AW(LBNP) = GRF, where Aw = cross-sectional area (CSA) of waist seal. However, the mobile Gravity Suit may achieve an additional GRF using the following equation, (AF + AW)LBNP = GRF, where AF = CSA of subject’s feet. The additional force can be further expressed as F1 + F2 = AF(LBNP), where F1 = spinal loading force, F2 = waist shear force, and AF(LBNP) = the total downward foot force. While lying supine, GRF data were recorded in both devices using foot sole sensors and a weigh scale. The data show that the Gravity Suit generated a mean maximum bodyweight of 125% +/- 22% whereas the LBNP chamber generated 91% +/- 24%. The mobile Gravity Suit demonstrates higher percent of bodyweight, due to the suit's novel biomechanical design.