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Increasing seated reaction forces with lower body negative pressure
Suhas Rao Velichala1, Jonathan Kim2, Alan R Hargens3
1Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, USA. suhasraov@gmail.com.
Abstract:
This study evaluates ground reaction forces and cardiovascular responses during seated lower body negative pressure (LBNP). Ten healthy subjects were exposed to randomized LBNP levels (-10 to -40 mmHg) while seated in a sealed chamber. Gluteal, foot, and total reaction forces, along with heart rate and blood pressure, were measured at each level. Reaction forces increased significantly with rising LBNP (P < 0.05), exceeding baseline at 10 mmHg and doubling by 30 mmHg. Cardiovascular parameters remained stable, indicating no acute hemodynamic risk. Force generation was dependent on LBNP amplitude and waist cross-sectional area. These findings suggest that seated LBNP is a safe and effective method to simulate Earth-like seated posture in microgravity, offering a promising countermeasure to mitigate musculoskeletal deconditioning and support gravitational adaptation during long-duration spaceflight.
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