# Horizontal running inside circular walls of Moon settlements: a comprehensive countermeasure for low-gravity deconditioning?

## TL;DR

A new exercise method using horizontal running inside circular walls could help astronauts combat health issues caused by low gravity on the Moon.

## Contribution

Proposes a novel exercise setup to simulate artificial gravity and counteract low-gravity deconditioning.

## Key findings

- Horizontal running inside a 4.7 m radius cylinder at lunar gravity can generate artificial gravity.
- Participants achieved high metabolic rates and forces comparable to terrestrial running.
- This method could prevent muscle and bone loss in astronauts.

## Abstract

Long-lasting exposure to low gravity, such as in lunar settlements planned by the ongoing Artemis Program, elicits muscle hypotrophy, bone demineralization, cardio-respiratory and neuro-control deconditioning, against which optimal countermeasures are still to be designed. Rather than training selected muscle groups only, ‘whole-body’ activities such as locomotion seem better candidates, but at Moon gravity both ‘pendular’ walking and bouncing gaits like running exhibit abnormal dynamics at faster speeds. We theoretically and experimentally show that much greater self-generated artificial gravities can be experienced on the Moon by running horizontally inside a static 4.7 m radius cylinder (motorcyclists’ ‘Wall of Death’ of amusement parks) at speeds preventing downward skidding. To emulate lunar gravity, 83% of body weight was unloaded by pre-tensed (36 m) bungee jumping bands. Participants unprecedentedly maintained horizontal fast running (5.4–6.5 m s−1) for a few circular laps, with intense metabolism (estimated as 54–74 mlO2 kg−1 min−1) and peak forces during foot contact, inferred by motion analysis, of 2–3 Earth body weight (corresponding to terrestrial running at 3–4 m s−1), high enough to prevent bone calcium resorption. A training regime of a few laps a day promises to be a viable countermeasure for astronauts to quickly combat whole-body deconditioning, for further missions and home return.