Effects of acceleration in the Gz axis on human cardiopulmonary responses to exercise

Eur J Appl Physiol. 2011 Dec;111(12):2907-17. doi: 10.1007/s00421-011-1917-0. Epub 2011 Mar 25.


The aim of this paper was to develop a model from experimental data allowing a prediction of the cardiopulmonary responses to steady-state submaximal exercise in varying gravitational environments, with acceleration in the G(z) axis (a (g)) ranging from 0 to 3 g. To this aim, we combined data from three different experiments, carried out at Buffalo, at Stockholm and inside the Mir Station. Oxygen consumption, as expected, increased linearly with a (g). In contrast, heart rate increased non-linearly with a (g), whereas stroke volume decreased non-linearly: both were described by quadratic functions. Thus, the relationship between cardiac output and a (g) was described by a fourth power regression equation. Mean arterial pressure increased with a (g) non linearly, a relation that we interpolated again with a quadratic function. Thus, total peripheral resistance varied linearly with a (g). These data led to predict that maximal oxygen consumption would decrease drastically as a (g) is increased. Maximal oxygen consumption would become equal to resting oxygen consumption when a (g) is around 4.5 g, thus indicating the practical impossibility for humans to stay and work on the biggest Planets of the Solar System.

MeSH terms

  • Acceleration*
  • Adult
  • Astronauts
  • Blood Pressure / physiology
  • Cardiac Output / physiology
  • Exercise / physiology*
  • Exercise Test / methods
  • Gravitation
  • Heart / physiology*
  • Heart Rate / physiology
  • Humans
  • Lung / physiology*
  • Male
  • Oxygen Consumption / physiology
  • Space Flight
  • Stroke Volume / physiology