Researchers Examine Spaceflight’s Impact on Muscle Decline

A recent study published in Stem Cell Reports investigates the effects of spaceflight on sarcopenia, a condition characterized by age-related muscle decline. Researchers aimed to understand how microgravity affects muscle cell function, particularly in older adults. This research may offer insights into mitigating muscle decline during long-duration space missions and could have implications for addressing similar issues on Earth.

To conduct the study, a team launched skeletal muscle microtissues from both young and older adult donors aboard the SpaceX CRS-25 mission to the International Space Station (ISS). This mission took place between July and August 2022. The primary goal was to evaluate muscle atrophy in prolonged microgravity conditions and assess the potential of electrical stimulation to counteract this effect.

Research indicates that astronauts can lose approximately 30 percent of their skeletal muscle mass after just one month in space due to the lack of gravitational force. This study revealed significant findings, showing that microgravity altered 86 muscle-specific age-associated genes. Notably, younger muscle fibers demonstrated a more positive response to electrical stimulation compared to older fibers, suggesting potential strategies for muscle preservation during space missions.

Dr. Siobhan Malany, an associate professor at the University of Florida and co-author of the study, stated, “Using electrical pulses to trigger real-time muscle contractions in space, we can simulate exercise and observe how it helps protect against rapid muscle weakening in microgravity.” This advancement offers valuable insights into maintaining muscle health during extended space travel and combating age-related muscle loss on Earth.

The phenomenon of muscle loss in microgravity has been well-documented since the inception of human spaceflight. During missions lasting only 5 to 11 days, astronauts can lose about 20 percent of their muscle mass, while longer missions can result in up to 30 percent loss. This decline is attributed to the reduced use of lower back and leg muscles, as astronauts do not experience gravitational pull.

To mitigate these effects, astronauts on the ISS engage in a rigorous two-hour daily exercise regimen, which includes running on a treadmill, cycling, and utilizing specialized equipment designed to mimic weightlifting on Earth. Recent findings on sarcopenia and spaceflight have emerged, including a 2023 study in Ageing Research Reviews, which examined the acceleration of aging due to space conditions, and a 2024 study in Scientific Reports, which looked at alterations in biological markers related to muscle health.

One significant example of the impact of long-term spaceflight is the year-long mission of NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko, who spent from March 2015 to March 2016 aboard the ISS. Upon their return to Earth, both astronauts experienced notable losses in bone and muscle mass, highlighting the necessity of understanding the physiological impacts of extended space missions.

The importance of addressing muscle loss during spaceflight becomes increasingly pressing as nations like the United States and China prepare to send astronauts to the Moon and eventually Mars in the coming years. While the Moon and Mars present different gravitational conditions—one-sixth and one-third of Earth’s gravity, respectively—protocols such as electrical stimulation could be pivotal for astronaut health on these missions.

As research continues to explore the connections between spaceflight and sarcopenia, the scientific community remains committed to uncovering innovative solutions to these challenges. The ongoing investigation into the effects of microgravity on muscle health not only aids space exploration but also contributes to better understanding and potentially addressing age-related muscle decline on Earth.