Research conducted aboard the International Space Station (ISS) is shedding light on how microgravity affects sarcopenia, the age-related decline in muscle mass, especially in older adults. A recent study published in Stem Cell Reports examined muscle cell function in microgravity, aiming to enhance understanding of the long-term health impacts of spaceflight on muscle deterioration. This research is particularly relevant as space agencies prepare for extended missions to the Moon and Mars.
The study involved sending skeletal muscle microtissues from both young and older adult donors on the SpaceX CRS-25 mission to the ISS, which took place between July and August 2022. Researchers sought to determine how muscles atrophy during prolonged exposure to microgravity and whether electrical stimulation could reverse this process. Previous studies indicate that astronauts can lose as much as 30 percent of their skeletal muscle mass after just one month in space, underscoring the urgency of this research.
Key findings revealed that microgravity affected 86 muscle-specific age-associated genes. Notably, younger muscle fibers demonstrated a more positive response to electrical stimulation compared to their older counterparts. Dr. Siobhan Malany, an associate professor at the University of Florida and co-author of the study, emphasized the potential of this technology: “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.”
The phenomenon of muscle loss in space is well-documented, with astronauts experiencing significant reductions in muscle mass due to the absence of the gravitational forces they encounter on Earth. During missions lasting between 5 and 11 days, astronauts can lose about 20 percent of their muscle mass, and those on more extended missions face even greater losses. This decline is primarily attributed to the lack of usage of lower back and leg muscles, which are not engaged in a standing position in microgravity.
To counteract these effects, astronauts aboard the ISS engage in a daily exercise regimen, spending two hours on a treadmill, stationary bike, and specialized equipment that mimics weightlifting. This preventive measure is vital for maintaining muscle and bone health during lengthy space missions.
Recent literature adds to the understanding of sarcopenia and spaceflight. A 2023 study in Ageing Research Reviews discussed how spaceflight accelerates aging, while a 2024 study in Scientific Reports investigated changes in biological markers due to microgravity. These studies highlight the pressing need to address muscle loss in astronauts, particularly as agencies like NASA and China plan lunar missions in the near future.
The one-year mission on the ISS involving NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko from March 2015 to March 2016 illustrated the real effects of prolonged space travel. Upon their return, both astronauts experienced notable losses in bone and muscle mass, emphasizing the critical nature of this ongoing research.
While future astronauts on the Moon and Mars will not encounter full microgravity—experiencing one-sixth and one-third of Earth’s gravity, respectively—protocols like electrical stimulation could significantly contribute to their long-term health. Understanding the connection between spaceflight and sarcopenia will continue to evolve, and ongoing research is essential to prepare for the challenges of long-duration space missions.
As scientists explore these connections, the implications extend beyond space exploration, offering insights into combating age-related muscle decline on Earth. The findings of this study serve as a reminder of the importance of advancing our knowledge in both space and health sciences.