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On March 18, a watery landing by NASA astronauts Sunita Williams and Butch Wilmore ended an unexpected nine-month stay in space. Though likely ready to jump for joy on land, the astronauts were carried out of their SpaceX crew capsule and loaded onto stretchers. Why? Two С��Ƭ��Ƶ professors walk us through the out-of-this-world impact that an extended stay away from gravity can have on the human body.

Ellen Glickman, Ph.D., professor of health sciences, told С��Ƭ��Ƶ Today that astronauts must be in great shape to tolerate the physical pressure of microgravity.  

“When an astronaut goes into space, the individual is placed under an enormous amount of stress,” Glickman said. “Their plasma volume is reduced and shifted and, consequently, their whole aerobic metabolic rate will change.”

С��Ƭ��Ƶ College of Podiatric Medicine professor and division head of clinical medicine and surgery, Joshua Moore, DPM, FACFAS, said bone loss and muscle atrophy are also some of the biggest physical concerns of being in space.  

“Space travel subjects the human body to microgravity, which is known to enhance bone loss compared to normal age-related bone loss here on Earth,” Moore said.

Astronauts often engage in a space exercise regimen to counteract bone loss and muscle atrophy. However, Glickman said the exercise is not as effective while under microgravity, and this drastic deconditioning can have a ripple effect on other physiological systems.

“Even though they’re trying to exercise, their lean body mass is reduced,” Glickman said. “They can’t exercise as intensely to maintain their aerobic metabolic rate, so every system is aging at a greater rate when under microgravity.”

Studies suggest bone loss occurs between 1-2% per month in space, which increases risk of fracture and fatigue of muscle groups. Moore says astronauts need to engage in normal and more aggressive musculoskeletal-related activity in order to prevent these fractures.

Moore and Glickman added cardiovascular and immune impairment to the list of potential complications that microgravity can have on the health of the astronauts.

“Heart rate becomes reduced due to the shift of bodily fluids under microgravity,” Glickman said. “This also causes orthostatic intolerance, which is when you get dizzy after quickly standing up.”

The pair’s reunion with Earth has just begun. Moore and Glickman said Williams and Wilmore will likely be assessed and followed by a well-trained medical team before undergoing a controlled exercise and therapy model to rebuild their bone and muscle mass.

“They came back to Earth on stretchers because they had been under so much stress for so long,” Glickman said. “Because the astronauts are in spectacular shape, they will recondition sooner, but it's a long-term process.”  

Glickman added that because of the combination of effects from the shift of fluids, the astronauts will need to focus on preserving their overall strength and balance, which includes adjusting to walking under Earth’s gravity.  

“It can take months, if not years, to recondition the body physiologically,” Glickman said. “During this long space exploration, it has been amazing to watch these wonderful individuals sacrifice their bodies for science.”

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