The four astronauts aboard the Artemis II mission will employ a specialized exercise machine known as the flywheel to counteract muscle and bone atrophy during extended periods in space. Research and development of the compact device have also indicated potential applications for maintaining physical health on Earth.
Impact of Space Travel on Human Physiology
Space travel causes significant changes to the human body, leading to muscle and bone atrophy due to the absence of constant gravitational pull.
Exercise physiologist Jessica Scott stated that ten days in space can be compared to ten days of bed rest, both of which result in weakness, reduction in muscle size, and increased vulnerability for the heart.
The Flywheel Device Overview
Canadian astronaut Jeremy Hansen described the flywheel's functionality, likening it to a rowing machine. Users strap their feet to a platform and pull a handle connected to a cable that spins a flywheel. The device is designed to provide resistance that matches the effort applied by the user.
Engineered for compact environments, the flywheel is approximately the size of a large shoebox, fitting within the Orion capsule's 316 cubic feet of space. It is capable of facilitating both cardiovascular workouts and resistance exercises, offering up to 400 pounds of resistance for movements such as squats, deadlifts, and curls.
Astronaut Reid Wiseman reported that a 30-minute aerobic session with the device provided an effective workout without generating excessive noise for his crewmates. He anticipates using it for future resistance training.
Research and Development
Jessica Scott, who contributed to early flywheel prototypes, highlighted the device's role in mitigating rapid muscle atrophy. Prototype testing involved a study with 30 participants, referred to as "pillownauts," who underwent 70 days of bed rest. Participants were divided into groups, some remaining in bed, some exercising with traditional equipment, and others using the flywheel. The primary objective was to prevent physical declines rather than to enhance fitness.
The flywheel demonstrated effectiveness in preventing physical declines, performing comparably to a full gym setup despite its small size. While its long-term efficacy for extended periods of gravity deprivation, such as on the International Space Station, has not yet been fully tested, Scott has expressed optimism regarding its potential.
Broader Applications on Earth
Radiologist Thomas Lang, whose research focuses on bone and muscle loss, noted the broader relevance of this technology for the general public. Human bone density and mass typically peak in the late twenties or early thirties and subsequently decline with age. This decline can be particularly sharp for women during menopause and can affect men in their 70s and 80s.
Scott also suggests that this work could benefit individuals facing limitations in time and space for exercise. She envisions future applications where personal flywheels, compact enough for home or office environments, could become available for public use.