Image Credit: The European Space Agency
I have often wondered about how males and females would respond differently to microgravity and how each gender would individually adapt to stressors, changing environments and the body's ability to adapt during a space mission. With space agencies preparing for future missions that will require both increased length of time in space and higher demand on the human body, it is becoming increasingly important for scientists, researchers, and space agencies to have an understanding of the effects of long-term exposure to microgravity on men and women.
The European Space Agency ran a series of studies called VIVALDI to see how men's and women's bodies react differently to the weightlessness of space. To simulate microgravity here on Earth, they used a technique called "dry immersion". Participants were gently suspended in a tank of water for five days, completely weightless but kept dry inside a special waterproof suit. It's one of the best ways scientists have found to mimic the feeling of floating in space without actually leaving the planet.
This type of research helps us understand how the human body adapts (or struggles) in space and why men and women might respond differently.
This method recreates several important effects of microgravity, including the upward shift of fluid from the body to the head (as occurs in space), the reduction of weight-bearing load on the muscles and bones, and the restriction of movement.
A total of 18 females participated in the VIVALDI-1 study and 19 males participated in the VIVALDI-2 study. Extensive physiological data were collected pre-, during and post-dry immersion in order to assess how the participants' bodies were responding. The results showed that dry immersion induces multi-system deconditioning in both men and women, affecting cardiovascular, metabolic, and musculoskeletal systems. Both sexes experienced fluid redistribution, reduced orthostatic tolerance, altered lipid profiles, and early markers of bone resorption. However, women exhibited a lower level of orthostatic tolerance compared to men, which suggests a greater degree of difficulty in adapting to the challenge of gravity-like stress. In addition, women also had relatively greater increases in their atherogenic indices and more prominent markers of bone resorption compared to men, which could mean that women may be more prone to developing cardiovascular, metabolic and skeletal problems during long spaceflight.
The authors concluded immersion is a valuable ground-based analogy for evaluating the physiological effects of exposure to microgravity. To protect astronauts’ health during long-duration spaceflight, it is important to consider the differences between male and females when developing strategies to prevent cardiovascular, metabolic, and skeletal issues. The findings from the VIVALDI Studies will help guide the development of better methods for maintaining astronaut health during and after extended periods in microgravity.
References
Robin, A., Custaud, M.-A., Navasiolava, N., Goswami, N., & collaborators. (2026). Sex‑specific cardiometabolic responses during microgravity simulation in European Space Agency VIVALDI dry immersion. Communications Medicine. https://doi.org/10.1038/s43856-026-01540-7
Contextual reference: Moser, D., et al.m (2026). Fluid shifts are main drivers for microgravity simulation - induced immune‑physiological changes: findings from the VIVALDI studies. npj Microgravity, 12, 15. https://www.nature.com/articles/s41526-025-00555-z
