# Increasing seated reaction forces with lower body negative pressure

## TL;DR

This study shows that applying lower body negative pressure while seated increases reaction forces safely, which could help simulate Earth-like posture in space.

## Contribution

The study introduces seated LBNP as a safe method to simulate Earth-like seated posture in microgravity environments.

## Key findings

- Reaction forces increased significantly with rising LBNP levels, 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.

## Abstract

This study evaluates 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.