Modeling human orthostatic responses on the Moon and on Mars

Abstract

While load of inertial resistance directly affects the magnitude of the transient blood pressure reduction and heart rate response to active standing, blood pressure stabilization is most rapidly attained during terrestrial +G. The observation might suggest that the human cardiovascular system is tuned to cope with orthostatic stress on earth.

Venous and Arterial Responses to Partial Gravity

“…We report here for the first time the heart rate and blood pressure responses across the range from 1.00-to 0.25-G z , although measures have been obtained during parabolic flight simulating lunar and Martian gravity (Widjaja et al, 2015;Beck et al, 2018). Lower mean arterial pressure has been reported previously while seated in 0-G produced by parabolic flight, likely resulting from increase in central blood volume (Lathers et al, 1989;Mukai et al, 1991), reduced sympathetic activity, and peripheral vasodilation (Iwase et al, 1999;Ogoh et al, 2015), but no similar data are available across this range of partial gravity levels.…”

Do astronauts get postural tachycardia syndrome? And other updates on recent autonomic research

“…Space medicine is an emerging subspecialty in contemporary medicine [3,12]. While it has been nearly 70 years since man first entered space, long-duration (i.e., longer than 300 days) spaceflight is still uncommon and represents a unique opportunity to study the effects of zero gravity on human physiology.…”

Extraterrestrial autonomic function

“…From their findings, Beck and colleagues [1] suggest that in some respects the haemodynamic response to active standing may not be proportional to gravitational load, but may instead be optimal under the orthostatic stress of planet Earth. The effects were modest and subject to all the limitations described above, but these preliminary findings are interesting to consider as humanity once again looks to explore other worlds.…”

“…Unlike in orbital spaceflight, where such changes of course do not exist, the unfamiliar gravitational environment on other moons or planets will naturally provoke their own version of this, which is interesting to study, not least because it could one day be relevant for astronaut explorers and eventually colonists from Earth. In work published in this issue of Clinical Autonomic Research, Dr. Beck and colleagues [1] have endeavoured to do this using parabolic flights to provide the relevant gravitational environments.…”

“…In other words, it feels like gravity is simply being switched on and off, which is incidentally a very pleasing sensation. It is also possible to fly shallower trajectories and achieve G levels between 0 G and 1 G, and Beck et al [1] made use of this to explore cardiovascular responses to active standing manoeuvres during lunar gravity (0.16 G for ~ 25 s per parabola) and Martian gravity (0.38 G for ~ 32 s) as well as hypergravity (1.8 G) during the pull-up phase.…”