Collapsing Astronaut Gives Healthy Reminder

On Friday, a day after the shuttle Atlantis returned after 12 days at reduced gravity, one of the astronauts collapsed twice during the welcome home ceremony. The reasons are the same as what happens here on Earth.

When you stand and sit on Earth, some of your blood pools in the veins of your legs because of the pull of gravity. In space, the pull of gravity is weak so blood does not pool. Blood floats upward. Astronauts and mission control scientists refer to the upward shift of blood during space flight in a technical manner. They call it the "Fat-Face-Chicken-Legs-Effect."

Upon return to the gravity of Earth, blood is again pulled downward. More pooling than usual occurs and not enough blood may be able to get to the brain. It is not uncommon for astronauts to feel weak and dizzy.

You may notice the same venous pooling on land in several situations: Sometimes when you stand suddenly, the rush of pooling in legs briefly lowers blood supply and blood pressure to your head. You may feel light headed. When this happens you just need to bend over and get your head down. Lowering your head allows gravity to restore blood, relieving dizziness. Extreme pooling has caused occasional cases of fainting when standing suddenly, when standing long periods at attention, and when climbing out of the water, especially hot water in spas and hot tubs. Pooling has been fatal to beached whales.

In space, the human body quickly gets badly out of shape without the pull of gravity. Muscles do not have to work to pull bones and quickly weaken. Bones do not have the muscular pull they need to stay dense and lose much calcium and bone mineral. Astronauts lose bone in space no matter how much calcium they eat. The cardiovascular system does not have to work as much to pump blood. This is why astronauts must exercise so much during missions.

Here on Earth you need regular activity that contracts leg and other muscles to squeeze the vessels to keep blood moving. After sitting for long periods at work and on a plane, your feet may swell with pooling fluids. Contracting your leg muscles while sitting, and by getting up and moving around pumps blood upward, reducing pooling and your risk of clots. For daily life, you need activity to keep muscles and bones from weakening. Even if you are sick it is crucial to get up and out of bed every day to stop the huge health losses that occur. Being sedentary is so devastating to health that bed rest is used as a model in scientific studies for loss of many health benchmarks in the microgravity of space. Stand to exercise, get outside, and enjoy some fun activity every day. Smile - another way to exercise against gravity.

Gravity and activity are important for health. Thank the astronaut, Heidemarie Stefanyshyn-Piper, for reminding us.

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Labels: aerospace, aging, blood pressure, circulation, leg strength, osteoporosis

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