title: Effects of acceleration in the Gz axis on human cardiopulmonary responses to exercise.
abstract: 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.
authors: Département de Neurosciences Fondamentales, Université de Genève, Rue Michel Servet 1, 1211, Geneve 4, Switzerland.
authors: Julien
authors: J
authors: Bonjour
authors: Aurélien
authors: A
authors: Bringard
authors: Guglielmo
authors: G
authors: Antonutto
authors: Carlo
authors: C
authors: Capelli
authors: Dag
authors: D
authors: Linnarsson
authors: David R
authors: DR
authors: Pendergast
authors: Guido
authors: G
authors: Ferretti
mesh_terms: D000054:Acceleration; D000328:Adult; D018480:Astronauts; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D006112:Gravitation; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008168:Lung / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D013026:Space Flight; D013318:Stroke Volume / Q000502:physiology