Effects of spaceflight on human calf hemodynamics

Donald E. Watenpaugh, Jay C. Buckey, Lynda D. Lane, F. Andrew Gaffney, Benjamin D. Levine, Willie E. Moore, Sheryl J. Wright, C. Gunnar Blomqvist

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


Chronic microgravity may modify adaptations of the leg circulation to gravitational pressures. We measured resting calf compliance and blood flow with venous occlusion plethysmography, and arterial blood pressure with sphygmomanometry, in seven subjects before, during, and after spaceflight. Calf vascular resistance equaled mean arterial pressure divided by calf flow. Compliance equaled the slope of the calf volume change and venous occlusion pressure relationship for thigh cuff pressures of 20, 40, 60, and 80 mmHg held for 1, 2, 3, and 4 min, respectively, with 1-min breaks between occlusions. Calf blood flow decreased 41% in microgravity (to 1.15 ± 0.16 ml·100 ml-1·min-1) relative to 1-G supine conditions (1.94 ± 0.19 ml·100 ml-1·min-1, P = 0.01), and arterial pressure tended to increase (P = 0.05), such that calf vascular resistance doubled in microgravity (preflight: 43 ± 4 units; in-flight: 83 ± 13 units; P < 0.001) yet returned to preflight levels after flight. Calf compliance remained unchanged in microgravity but tended to increase during the first week postflight (P > 0.2). Calf vasoconstriction in microgravity qualitatively agrees with the "upright set-point" hypothesis: the circulation seeks conditions approximating upright posture on Earth. No calf hemodynamic result exhibited obvious mechanistic implications for postflight orthostatic intolerance.

Original languageEnglish (US)
Pages (from-to)1552-1558
Number of pages7
JournalJournal of applied physiology
Issue number4
StatePublished - 2001


  • Blood flow
  • Gravity
  • Leg
  • Vascular resistance
  • Venous compliance
  • Weightlessness

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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