what happens to the muscles of astronauts who are in space for an extended period?

Curt-term missions of a month or less have relatively mild affects on an astronaut's body, just a year-long space odyssey like Scott Kelly'south carries with it more significant physiological stresses that are often only felt upon render to World.

NASA astronaut Scott Kelly gives himself a influenza shot on board the International Space Station as a office of an ongoing written report on the human immune system in infinite on Sep. 24, 2015. (NASA via Getty Images)

Ground control to Scott Kelly: you're going to experience a bit featherbrained.

Afterward spending 340 days in space — breaking an American record past 125 days — the NASA astronaut returned domicile from the International Space Station, touching down yesterday in Kazakhstan. Kelly even received a call from U.S. President Barack Obama thanking him for his service, according to the White House.

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Space missions forcefulness astronauts to live and work in tough environments human being beings aren't accepted or acclimatized to, but short-term stints of 1 calendar month or less have relatively balmy effects, according to the Canadian Infinite Bureau.

A space odyssey every bit long equally Kelly's, notwithstanding, carries with it more meaning physiological stresses that are often only felt upon return to Earth.

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"In the same mode that every organ organisation needs to adjust to weightlessness, every organ system needs to re-adapt afterwards a long menstruum of time back to an Earth environs," Canadian astronaut Bob Thirsk previously told CBC News.

Here are some of the effects space has on the human body:

Bones

Co-ordinate to the Canadian Space Bureau, astronauts can lose on average 1 to ii per cent of their bone density a month, mostly in their legs.

Bones are constantly reshaping themselves in relation to the stress put upon them, and loss occurs in infinite'southward weightless surround because your trunk devotes less free energy to build a tougher bone structure to fight gravity if it doesn't seem necessary.

"Your basic are ... beingness continually eaten away and replenished," Bjarni Tryggvason, i of Canada's first astronauts, told CBC in 2013.

"The replenishment depends on the actual stresses in your bones and information technology'south mainly ... bones in your legs where the stresses are suddenly reduced [in infinite] that you lot encounter the major bone loss," he said.

Canadian astronaut Bob Thirsk said information technology took about a year for his bone calcium levels to return to normal post-obit a half dozen-month space mission. (Canadian Space Agency via Canadian Press)

The excess os affair is discharged from your torso via your urine, said Chris Hadfield.

"The outset time you pee in space, your urine is total of your skeleton," he said during a 2011 presentation to the Royal Astronomical Society of Canada.

Astronauts are told to work out for a couple of hours a day, and accept nutritional supplements and medication prescribed to mail-menopausal women to try and counter the bone loss, but rehab is still needed.

Thirsk, who underwent a six-month space mission in 2009, said it took nearly a yr for his bone calcium levels to return to pre-flight levels.

"The rule of thumb is for every month in infinite, it takes two months for the bones to recover," he said.

Muscles and joints

Long-term space missions can reduce muscle mass and forcefulness, again caused past reduced gravity and again affecting largely the legs.

Similar the reverse of wearing a weighted exercise vest, low gravity means less strain to your muscles causing them to weaken.

Astronauts tin lose as much as xx to 40 per cent muscle size and role during long trips in infinite, according to NASA.

The two hours they spend exercising mitigates the deterioration to a degree, but, like with bone loss, astronauts become through a rehab programme when they're back on Earth to regain their muscle mass and force.

Muscle resistance exercises "don't stop the deterioration in our trunk, but it slows it down," said Thirsk.

He also said inside six weeks of return to Globe, he was able to get his muscles back to pre-flight condition.

NASA astronaut Sunita Williams performs an extravehicular activity, or EVA, on Sep. five, 2012. Astronauts can become 'the bends' if they do not take proper precautions before EVAs. (NASA via Getty Images)

Astronauts can also go through decompression sickness.

DCS — or "the bends" if you're familiar with scuba diving or early on Radiohead — occurs when the body goes through rapid and tremendous decreases in atmospheric pressure, such equally resurfacing too quickly in water.

It creates tiny nitrogen bubbling in the bloodstream and tissues, which causes symptoms ranging from numbness to joint pain.

Astronauts tin can get DCS by going from normal cabin pressure — the ISS is pressurized to 14.7 psi, the equivalent to the atmospheric pressure at bounding main level — to a lower atmospheric force per unit area, like when they go on extravehicular activities (EVA).

To reduce risks of DCS, astronauts breathe 100 per cent pure oxygen for one to two hours at normal cabin pressure, and and then reduce the pressure from 14.7 to 10.21 psi for 12 hours. Then, after wearing the EVA mobility suit, they breathe 100 per cent oxygen for i more hour before going outside.

Cardiovascular

Soon after being launched into space, an astronaut's claret moves upward from the legs to the upper body and head.

The torso's natural reaction is to decrease the amount of claret in the body, and when an astronaut goes from zero gravity to normal or partial gravity — such as coming dorsum to Earth from space — the decreased amount can result in temporary depression blood pressure.

This affects the astronauts' motor skills and can hinder their ability to do everyday things, like walking or driving a automobile, and some astronauts may faint later space flights.

"I had problem maintaining blood force per unit area to my head and therefore I felt pretty faint and empty-headed," said Thirsk. "In fact, I needed to take a transfusion of normal saline to get my blood pressure up shortly after I got back."

Astronauts can also experience heart and blood vessel bug down the line, such as artery stiffness, according to University of Waterloo professor Richard Hughson.

"The astronauts came back from space with carotid arteries that were about 20 to xxx years stiffer equivalent than what happens with normal crumbling," said Hughson.

Increased stiffness of the arteries is associated with increased risks of eye disease and stroke.

Eyes

A 2012 report linked prolonged periods in the zilch gravity of space with middle abnormalities.

Astronauts have complained for decades virtually vision problems such as blurriness post-obit trips into space, and a NASA survey of 300 astronauts found correctable near and altitude vision bug in 48 per cent of those who had brief missions.

Scott Kelly snaps a quick selfie during a spacewalk on Dec. 21, 2015. Astronauts take complained for decades about vision problems following trips into space. (Scott Kelly/NASA/Getty Images)

In some cases, the vision problems lasted for years afterwards the astronauts returned to Earth.

The study suggested the bug might exist due to fluid shifting toward the head during extended periods of fourth dimension in microgravity.

This could outcome in aberrant flow of spinal fluid around the optic nerve, changes in claret flow in the vessels at the dorsum of the heart or chronic depression pressure within the eyes, the researchers said.

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Source: https://www.cbc.ca/news/science/astronauts-space-body-physical-effect-1.3474101

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