Study Links Spaceflight to Age-Related Muscle Decline Insights

Research published in *Stem Cell Reports* sheds light on how microgravity during spaceflight affects sarcopenia, the age-related decline in muscle mass, particularly among older adults. The study, conducted by a team of scientists, aims to enhance understanding of muscle function in microgravity and its long-term health implications for astronauts and the broader population.

As part of the investigation, skeletal muscle microtissues from both young and older adult donors were launched aboard the SpaceX CRS-25 mission to the International Space Station (ISS) from July to August 2022. The primary objective was to determine how muscles atrophy in response to extended periods in microgravity and to explore the potential for electrical stimulation to reverse this process.

Research indicates that astronauts can lose around 30 percent of their skeletal muscle mass after just one month in microgravity. The study found that microgravity influenced 86 muscle-specific age-associated genes. Notably, younger muscle fibers demonstrated a more favorable response to electrical stimulation compared to their older counterparts. This discovery could lead to methods that help mitigate muscle loss during extended space missions.

Dr. Siobhan Malany, an associate professor at the University of Florida and a co-author of the study, emphasized the potential benefits of using electrical pulses to simulate muscle contractions in space. “By triggering real-time muscle contractions, we can simulate exercise and observe how it protects against rapid muscle weakening in microgravity,” she explained. “This technological advancement offers insights into preserving muscle health during long-duration space missions and combating age-related muscle loss on Earth.”

The phenomenon of muscle loss in microgravity has been well-documented since the early days of human spaceflight. Astronauts experience approximately 20 percent muscle mass loss during missions lasting just 5 to 11 days, escalating to a potential 30 percent on longer missions. This deterioration is attributed to the reduced need for lower back and leg muscles, as astronauts do not stand in space.

To combat muscle atrophy, astronauts aboard the ISS follow a rigorous exercise regimen, dedicating two hours daily to activities such as running on a treadmill, cycling, and using specialized equipment that simulates weightlifting. Recent studies have further explored the relationship between sarcopenia and spaceflight. A 2023 study in *Ageing Research Reviews* discussed how spaceflight accelerates aging, while a 2024 study in *Scientific Reports* examined how space travel alters biological markers.

Past missions, such as the year-long stay of NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko on the ISS from March 2015 to March 2016, illustrated the impact of prolonged spaceflight on muscle and bone health. Upon their return to Earth, both astronauts experienced significant loss of muscle and bone mass, underscoring the need for ongoing research into the physiological effects of extended space missions.

As space agencies, including those from the United States and China, plan for lunar and Martian expeditions in the coming years, understanding and countering muscle loss during spaceflight becomes increasingly crucial. While future astronauts will not encounter full microgravity—experiencing only one-sixth of Earth’s gravity on the Moon and one-third on Mars—techniques such as electrical stimulation could provide vital support for their health during long missions.

The ongoing research into the connections between spaceflight and sarcopenia is poised to yield further insights in the years ahead. The pursuit of knowledge in this field is essential not only for the future of human space exploration but also for addressing age-related health issues on Earth. As the scientific community continues to explore these connections, the potential benefits for both astronauts and aging populations remain a promising frontier.