Could Running Around a ‘Wall of Death’ Help Astronauts Stay in Shape on the Moon?

Short sprints on these cylindrical structures, long used by daredevil motorcycle riders, might promote muscle mass and bone density in low-gravity conditions

Woman tied to a bungee cord running around a cylindrical wall
Astronauts could run around the interior walls of cylindrical homes on the moon. Minetti et al. / Royal Society Open Science, 2024

For decades, daredevils have ridden motorcycles parallel to the ground, driving in circles around an apparatus called the “wall of death.” Often surrounded by spectators, the motorists move through the massive, wooden cylinder using inertia, friction and centrifugal force to remain upright—and avoid crashing to the ground.

Now, scientists say these popular carnival sideshows may one day help astronauts stay in shape on the moon. Running around a cylinder for a few minutes each day could be enough to help counteract some of the negative health effects of living in a low-gravity environment, researchers report Wednesday in the journal Royal Society Open Science.

Humans have not visited the moon since 1972, at the end of the Apollo program. But, through NASA’s Artemis missions, astronauts could set foot on the moon as soon as 2026. Longer term, the space agency hopes to set up a permanent settlement on the moon to help prepare for possible human missions to Mars.

Living on the moon, however, will be difficult for numerous reasons. Setting aside the challenge of ensuring astronauts have enough food, water and oxygen to survive, NASA will also need to keep them healthy and strong.

Lunar gravity is about one-sixth the strength of Earth’s. Because their bodies won’t have as much gravitational resistance to contend with every day, astronauts will quickly lose muscle mass and bone density, as well as cardiovascular fitness. On the International Space Station, astronauts run on a zero-gravity treadmill while attached to a harness. But even this doesn’t compare to jogging under the force of gravity at home. And, as Darren Incorvaia writes for Science, “running in low gravity is awkward.”

A team of researchers wondered if a wall of death might help solve this problem. On Earth, runners can’t move fast enough to fight gravity and remain on the wall. But what about on the moon, where gravity is much weaker?

To test this theory, the scientists rented a wall of death from an amusement park and set up a 118-foot telescopic crane nearby. They attached bungee cords to two volunteers, then used the crane to support most of their weight as a way of mimicking the moon’s gravity. This setup made them effectively 83 percent lighter than normal, as they would be on the moon.

Separately, the volunteers—one man and one woman—then tried running around the wall of death, which was nearly 100 feet in circumference. They completed a couple of laps at high speeds of roughly 12 to 14.5 miles per hour. Under the mock low-gravity conditions, they were able to stay on the wall as they sprinted.

In doing so, the runners experienced forces that were similar to those exerted by gravity on Earth. On the moon, this type of exercise could help them maintain strong bones and retain muscle mass. After looking at the volunteers’ data, researchers suggest that “running twice a day, for a few minutes at a time, should be enough,” says study co-author Alberto Minetti, a physiologist at the University of Milan in Italy, to New Scientist’s Chen Ly.

But transporting a wall of death to the moon could pose a logistical problem for space agencies—the one used in the study was roughly 31 feet in diameter. Instead of moving such a large cylinder through space or constructing one on site, the researchers propose building cylindrical homes for astronauts living in the lunar settlement. Then, they could just run around the walls of these structures.

Not everyone is convinced the wall of death is such a good idea for the proposed lunar settlement. Other researchers are also brainstorming exercise methods that don’t take up quite so much room or require nearly as much movement, such as using inflatable cuffs to compress astronauts’ limbs and restrict their blood flow as they work out.

“Blood flow restriction exercise has been shown in studies on Earth to give similar muscle, bone and cardiorespiratory training benefits normally seen during higher intensity exercise, at much lower exercise intensities and durations,” says Nick Caplan, an aerospace medicine and rehabilitation researcher at Northumbria University in England, to the Guardian’s Ian Sample. “This may, therefore, make existing exercise countermeasures more effective at keeping astronauts healthy without the need for a lunar wall of death.”

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