The Effects of Varying Gravito-inertial Stressors on Grip Strength and Hemodynamic Responses Across Gender

The body behaves as a global system with many interconnected subsystems. While the effects of a gravitational change on body responses have been extensively studied in isolation, we are not aware of any study that examined two types of body responses concurrently. Here, we examined how the neurocognitive and cardiovascular systems interact in this singular context and whether these combined responses are influenced by gender. Ten women and nine men underwent three 5-minute centrifugation sessions (2.4g at the feet, 1.5g at the heart) in which participants rhythmically moved a hand-held object for 20 seconds. Grip force and hemodynamic responses were continuously measured during centrifugation and rest periods. Our results show that men optimize the modulation between grip force and the destabilizing load force, but not women. Exposure to artificial gravity induced higher heart rate and mean arterial pressure in both genders compared to baseline. However, during exposure, only women decreased heart rate across sessions. Interestingly, we found that Finishers (N=13, mostly men) and Non-Finishers (N=6, mostly women) exhibited divergent patterns of hemodynamic responses. We also suggest that the lack of grip force adaptation reported in women can be linked to challenged hemodynamic responses in that population. Finally, by deriving a simple model to predict failure to complete the experiment, we found that mean arterial pressure was the most relevant dimension, and not gender. As artificial gravity is being proposed as a countermeasure in long-term manned missions, our results are particularly important but also deserve follow-up studies.