title: Cardiovascular autonomic adaptation in lunar and martian gravity during parabolic flight.
abstract: OBJECTIVE
  Weightlessness has a well-known effect on the autonomic control of the cardiovascular system. With future missions to Mars in mind, it is important to know what the effect of partial gravity is on the human body. We aim to study the autonomic response of the cardiovascular system to partial gravity levels, as present on the Moon and on Mars, during parabolic flight.
  
  
  METHODS
  ECG and blood pressure were continuously recorded during parabolic flight. A temporal analysis of blood pressure and heart rate to changing gravity was conducted to study the dynamic response. In addition, cardiovascular autonomic control was quantified by means of heart rate (HR) and blood pressure (BP) variability measures.
  
  
  RESULTS
  Zero and lunar gravity presented a biphasic cardiovascular response, while a triphasic response was noted during martian gravity. Heart rate and blood pressure are positively correlated with gravity, while the general variability of HR and BP, as well as vagal indices showed negative correlations with increasing gravity. However, the increase in vagal modulation during weightlessness is not in proportion when compared to the increase during partial gravity.
  
  
  CONCLUSIONS
  Correlations were found between the gravity level and modulations in the autonomic nervous system during parabolic flight. Nevertheless, with future Mars missions in mind, more studies are needed to use these findings to develop appropriate countermeasures.
authors: Department of Electrical Engineering (ESAT)-STADIUS, iMinds Medical Information Technologies, KU Leuven, Kasteelpark Arenberg 10, box 2446, 3001, Leuven, Belgium, devy.widjaja@esat.kuleuven.be.
authors: Devy
authors: D
authors: Widjaja
authors: Steven
authors: S
authors: Vandeput
authors: Sabine
authors: S
authors: Van Huffel
authors: André E
authors: AE
authors: Aubert
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure; D002319:Cardiovascular System / Q000294:innervation; D006339:Heart Rate; D006801:Humans; D008297:Male; D014893:Weightlessness