Wall of Death Could Help Lunar Astronauts Exercise on the Moon

Few aspects of life are guaranteed. Yet it appears very likely that, within the next decade or so, people will venture across the lunar surface and remain there for periods of weeks or possibly months. That prospect collides with a well-established certainty: spending time in low-gravity settings places considerable strain on the human body.

What can be done about it?

Scientists have investigated how microgravity and reduced gravity affect people. The resulting difficulties include muscle wasting and loss of bone mineral density. Cardiovascular fitness deteriorates, while the neural control of posture and movement is also affected. Although research is steadily improving understanding of these effects, effective countermeasures have been slower to emerge.

A new study in Royal Society Open Science puts forward an unconventional low-tech answer. Its title is "Horizontal running inside circular walls of Moon settlements: a comprehensive countermeasure for low-gravity deconditioning?" The paper’s lead author is Alberto Minetti, Professor of Physiology at the University of Milan.

Whole-body exercise for lunar astronauts

Minetti and his fellow researchers argue that targeting individual problems with separate exercises may not be the most effective strategy. In their view, activities involving the entire body could offer a strong means of protecting astronaut health.

"Rather than training selected muscle groups only, 'whole-body' activities such as locomotion seem better candidates,"

the researchers explain. However, such exercise presents a challenge. As they write:

"But at Moon gravity, both 'pendular' walking and bouncing gaits like running exhibit abnormal dynamics at faster speeds,"

These unusual dynamics mean astronauts gain limited benefit from this kind of activity. The issue is constrained by an " … imbalance between the kinetic and potential energy of the body center of mass," according to the authors.

In practical terms, running cannot deliver the same exercise stimulus on the Moon that it provides on Earth.

"Additionally, the metabolic demands of bouncing gaits are reduced at Moon gravity, limiting their potential stimulus for cardiorespiratory fitness,"

the authors explain.

Potential methods do exist to help lunar astronauts preserve their health in reduced gravity. A centrifuge, for example, could use rotation to mimic gravity and encourage the body to retain muscle and bone mass. However, centrifuges consume substantial energy and are not especially practical.

A Wall of Death on the Moon

Instead, the researchers suggest a different approach. Have you ever watched a Wall of Death?

"Here, we propose a novel solution: lunar inhabitants could engage in running on the inside of vertical circular walls, hence running parallel to the Moon's surface,"

the authors write.

Exercise within a Wall of Death (WoD) could help sustain muscle mass, bone density, cardiovascular fitness and neural control.

Earth’s gravity is too powerful for people to run around the interior sides of a WoD. This is possible only for motorised vehicles and bicycles. On the Moon, however, lower gravity could make the activity feasible for humans.

To investigate the idea, the team modelled a lunar WoD and assessed subjects running within one. They rented a WoD for a day, then used a bungee-cord harness to reduce the participants’ effective body weight and recreate the Moon’s weaker gravity.

The experiment involved two people: a 36-year-old man and a 33-year-old woman. The bungees were adjusted so that each person effectively weighed one-sixth of their normal body weight. The harness also unloaded one side of each subject’s body to more closely replicate lunar conditions. Data gathered in the WoD were combined with treadmill measurements for more robust findings.

Once the participants had entered the WoD and been attached to the harness, the experiment took this form.

Learning horizontal running inside the WoD

The subjects rapidly adapted to the unfamiliar movement needed to run horizontally around the inside of the WoD.

"This process required only 5–8 attempts and allowed them to start running with no assistance,"

the authors write. The participants:

"… ended their performance by safely slowing down their pace and descending from the horizontal posture on the wall down to the upright one on the WoD floor, with no injuries,"

they explained.

According to the authors, the experiment successfully established the basic feasibility of using a WoD to promote the health of lunar astronauts.

"We have demonstrated for the first time that humans can safely run horizontally in low gravity conditions inside a cylinder, sized as a terrestrial 'WoD', through a speed-driven, self-generated higher artificial gravity,"

they explain.

The research team believes the Wall of Death concept could assist lunar astronauts in managing the long-term consequences of lunar gravity. Nevertheless, they acknowledge the limited sample size and other constraints of the work.

"In conclusion, while being aware of the small sample size, of the crudeness of kinematics acquisition in such a peculiar field experiment, and that dedicated bed rest studies will be needed to refine this topic, we are confident in our findings,"

they write in their conclusion.

Although conventional running on the Moon is not possible, the WoD could allow astronauts to obtain running’s benefits through brief daily exercise sessions.

Participants in the WoD generated:

"… a sufficiently high (lateral) self-generated artificial gravity likely capable of maintaining, through a few short, almost 'terrestrial' running laps a day, an acceptable cardio-motor fitness and bone mineral status, useful to locally move and work around, to prepare the long trip to Mars, and to return home in good condition."

There is a certain elegance to low-tech answers for difficult problems. Rather than relying on a complex, energy-intensive device such as a centrifuge, a straightforward WoD might counter the Moon’s low gravity.

"All of this, by using an inexpensive and passive facility already built in their circular inhabited units,"

the authors conclude.

This article was originally published by Universe Today. Read the original article.