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Bungee Cords Keep Astronauts Grounded While Running
Sunni Williams on International Space Station

Astronaut Suni Williams bungeed to the TVIS treadmill aboard the International Space Station.
Credit: NASA
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Colbert patch Official patch for "COLBERT," the Combined Operational Load Bearing External Resistance Treadmill, due to launch on shuttle Discovery as early as August 2009. (Click image to enlarge.)
Credit: NASA

International Space Station astronauts are getting a new toy in August – a treadmill. Famously named after comedian Stephen Colbert, the new running machine will help astronauts stay fit, fighting off the bone loss and muscle decay that otherwise comes with space travel.

Just one problem: How do you run where there's no gravity to hold your feet to the ground?

"Bungee cords! You have to strap yourself to the treadmill," explains astronaut Sunita "Suni" Williams. And she's not joking.

In 2007, she ran the Boston Marathon on the station's TVIS treadmill wrapped in bungee cords for the entire 26.2 mile race.

"It's not as bad as it sounds," she laughs.

TVIS stands for "Treadmill with Vibration Isolation System." It's the space station's original treadmill, designed to allow astronauts to run without vibrating delicate microgravity science experiments in adjacent labs. COLBERT, short for "Combined Operational Load Bearing External Resistance Treadmill", has a different kind of vibration-suppression system plus some other improvements for runners:

"I tried a COLBERT mockup at Johnson Space Center," says Williams. "It's broader than TVIS, so you don't have to watch out where your feet go. It allows a wider, more natural gait."

Williams spent a lot of time running during her six months on board the International Space Station, and she recalls what it's like:

"Just getting ready to run is a workout when you're weightless. Before all my training runs up there, I had to hook the toes of one foot under a handrail to keep from floating around while I struggled to put my sock and shoe on my other foot."

"I did this so often, it made calluses on top of my feet. Meanwhile, the calluses on the bottoms of my feet from running on Earth went away. It's totally upside down and backwards!" she laughs.

The treadmill's bungee harness "can be a bit uncomfortable," she continues. "During the marathon my foot sometimes went numb and tingly from the straps' pressure on my hip. Also, I had to use moleskin where the harness rubbed my neck raw."

And inside the close, still quarters of the space station, there are no gentle breezes to cool you down.

"Sweat globs onto you. It doesn't evaporate. I was soaking wet. During the marathon my hair was so sopping it flopped right in my face. We have little fans blowing on us but they don't do much good."

And Williams missed more than the soft winds of Earth.

"On Earth, the crowd cheers you on and you enjoy the camaraderie and support of the other runners. In space it's a little bit lonely. I was by myself most of race. My crewmates did cheer me through the last half hour to the finish. That was great!"

"Also, one of the Soyuz astronauts floated sweet, juicy pieces of oranges to me – so refreshing!"

After the grueling run, Williams longed for a hot shower. "A sponge bath just isn't the same!" she says. Neither did she have a washer and dryer for cleaning her sweat-soaked running clothes. "I hung my drenched clothes near a fan and tied my sneakers to a handrail to air them out."

Williams is the only person to have run the Boston Marathon on Earth and in space—and she noted some interesting differences:

"I recovered faster after the space marathon. When you're floating, your muscles get to rest, so you can totally relax when you finish running – it's like being in a pool."

"Also, the space marathon didn't give me the same endorphin effect – that wonderful mood lift runners enjoy after running – as the Earth marathon did. I'm not sure why," she says. "We are loaded with only about 60% of our Earth weight on TVIS and its harness system, so maybe I just didn't work hard enough!"

Williams says she'd consider running another marathon on COLBERT. "If another astronaut challenges my time, maybe I’ll do it. I have a competitive nature."

When it comes to running, you could say "it's out of this world."
Author: Dauna Coulter
Editor: Tony Phillips