Last Updated on Jan 09, 2020

Puffy-face and Bird-legs Syndrome

A progressive shift of body fluids and blood from the lower extremities to the upper body occurs in the absence of Earth’s gravitational force.

Initially, this headward shift increases the central fluid volume, cardiac size (around 20%) and cardiac output. It then leads to a negative fluid balance and reduction of 12-20% in the circulating blood volume, which causes a decreased resting stroke volume of 10-20% and a reduced cardiac output with an average of 1.5L.min-1 lower than pre-flight values. These changes are secondary to the reduction in circulating blood volume. This condition has been nicknamed the puffy-face and bird-legs syndrome, as the face of the astronaut becomes rounded, redder and more swollen, while the legs become thinner, due to the redistribution of fluids and blood from the lower to upper body.(3) The situation is reversed when the astronaut is once more subject to the gravitational force of the Earth, which distributes the fluid and blood back to its original position.

Puffy-face and Bird-legs Syndrome


  1. What is microgravity? - (
  2. Human Pathophysiological Adaptations to the Space Environment - (
  3. Astronaut Lingo: What Is Puffy Head Bird Legs? - (
  4. Recent Findings in Cardiovascular Physiology with Space Travel - (
  5. Spaceflight-Induced Intracranial Hypertension and Visual Impairment - Pathophysiology and Countermeasures - (
  6. Emergencies in Space - (
  7. Artificial gravity as a countermeasure for mitigating physiological deconditioning during long-duration space missions - (

Most Popular on Medindia