Working in a microgravity environment allows astronauts to grow about 3 percent taller.
But extended time in weightlessness can also accelerate bone loss, causing astronauts to lose bone mass at about the same rate as a postmenopausal woman.
A NASA scientist has been studying this rapid bone deterioration and thinks her findings on what’s experienced in space can be used here on Earth — as well as potential future missions to Mars.
The average adult human has 206 bones in their body. Those bones are constantly breaking down and regenerating.
This cycle poses a problem for astronauts because in microgravity, bones break down, but they don’t regenerate.
“What we’re seeing is some kind of form of osteoporosis in our astronauts,” said Dr. Tara Ruttley, an associate program scientist for the International Space Station. “The insides of the bones start to weaken because the minerals are kind of lost. They also lose a lot of calcium from their bones and it goes into their urine and they’re prone to increased kidney risk as well.”
Ruttley says part of the reason for that bone loss is astronauts float around a lot on the space station.
So she tells them to exercise for about two-and-a-half hours each day. They walk or run on a treadmill. They also work out on a machine that helps them do weight lifting exercises like squats and deadlifts — in microgravity.
“Absolutely no load is on their body until they get on that treadmill and they’re loaded down, strapped down to the treadmill or they get on their resistive exercise device and start doing their exercise,” Ruttley said.
Scientists test astronauts’ bones, blood and urine over about a six month period, including before launch, while they’re in flight and when they return home.
Based on all that testing, they’ve figured out astronauts need about 800 IUs of Vitamin D per day to maintain their bone mass — about the same dose many earthbound people over the age of 70 take.
Here on Earth, we lose bone mass too, but much more slowly. That’s because a lot of us aren’t getting enough exercise or calcium in our diet.
The older we get, the more fragile our bones become — putting us at a higher risk of falling and fracturing them. This is where NASA’s research on astronauts’ bone loss can help on Earth.
Dr. Margaret Guest-Desham: You haven’t had any falls really?
Peter B. Kaplan: I haven’t had any falls in quite a while.
Guest-Desham: Are you still receiving outpatient therapy?
Kaplan: Yeah, twice a week.
Peter B. Kaplan is a 79-year-old photographer from Hockessin. He once climbed the antenna of the World Trade Center, but now, he struggles to keep his balance on flat surfaces.
He has peripheral neuropathy — a condition that causes him to lose balance. He’s receiving treatment at Christiana Care Health System’s Safe Steps program.
About a week ago, two doctors watched him walk across a room at Wilmington Hospital to understand why he’s been falling.
Dr. Lynsey Brandt: Now you can use your arms wherever you feel comfortable and natural, you're going to walk up to Dr. Guest, walk around her and come on back at your own safe comfortable speed and sit back down. And let's go ahead.
Brandt: Use your arms in the chair if you’d like. Very good.
Doctors want to help him now before the problem gets worse and he breaks a bone.
Kaplan: The worst part is I’ve got to remember when I walk I gotta really spread my legs and walk...
Kaplan: ...with this distance in between. Cos I tend to (his feet make a sound)...
Guest-Desham: ...keep your feet close together. So when they’re farther apart your balance is much better.
Guest-Desham: Right? That’s what they’re teaching you in therapy.
So Peter B. is taking a lot of precautions, and doctors say that’s a good thing.
Dr. Brian Galinat is an orthopedic surgeon at Christiana Care. He says bones are pretty much use them or lose them. Without enough calcium in your diet, your bones become more brittle and you risk breaking them.
“The simple things everyone can do — proper exercise, diet, and Vitamin D — These are things that people forget about,” Galinat said. “And you end up finding out you have a problem when you break a bone. You don’t want to do that.”
Sound familiar? Well — NASA has found the same thing. Whether a person is in space or on Earth, they need exercise and Vitamin D to build strong bones.
Galinat says since microgravity has allowed NASA to study bone health at a faster pace, it’s helped Christiana Care researchers make improvements to medicine and their bone health programs more quickly.
“We’ve had further confirmation of the idea that weight bearing exercise is good for the skeleton,” Galinat said. “There is still a lack of awareness of Vitamin D levels and how that can affect bone health and all types of healing.”
As NASA continues to research bone health in space to help their astronauts get to Mars one day, Galinat said he’s looking forward to future findings.
Those findings could help patients with weaker bones here in Delaware take one small step for man, one giant leap for mankind — without falling.