Tian Fan, Yang Yuan, Wang Hong, Li Jiao, Xie Jing, Gao Junfeng, Zhang Li, Liu Xin, Wang Yuan, Li Ke, Gu Jianwen, Strategic Support Force Characteristic Medical Center, Aerospace Clinical Medicine Department, Manned Space Medical Team, and Special Service Medical Department
During long-term space flight, astronauts will undergo a series of physiological changes, and space musculoskeletal loss is of particular concern, that is, the phenomenon of reduced muscle and bone mass in microgravity environment. This phenomenon not only affects health, but also poses a potential threat to their ability to work in space.
The microgravity environment is the main cause of this phenomenon. On Earth, gravity exerts a constant load on bones and muscles, stimulating growth and maintenance. In space, however, the gravitational load almost disappears, bones become brittle, and muscles atrophy.
The detailed research and analysis of the musculoskeletal loss of astronauts are as follows:
- Loss of bone and mineral salts: 1% to 2% per month, and adaptation to life in space does not make this phenomenon disappear, long-term work may cause irreversible physiological changes.
- The impact of weightlessness on bones: human tissues and organs adapt to the earth's 1g gravity, and weightlessness in space reduces the pressure on weight-bearing bones, reduces muscle movement, weakens bone stimulation, causes bone density, and causes osteoporosis and other symptoms.
- Disruption of osteocyte metabolic balance: In the weightless environment, the function of osteoblasts is inhibited, and osteoclasts are more active, resulting in osteoporosis and calcium metabolism disorders.
Astronaut sarcopenia is one of the specific manifestations of aerospace musculoskeletal loss, which refers to a significant decrease in muscle mass accompanied by a decrease in muscle strength and function. For astronauts, not only is it difficult to physically move in space, but there is also an increased risk of injury after returning to Earth.
In response, researchers have done a lot of research. On the one hand, we should understand the specific mechanisms of microgravity on musculoskeletal effects, and on the other hand, we should develop effective countermeasures to mitigate or reverse the effects.
To understand the mechanism, the researchers used ground-based microgravity simulation devices, such as bed rest experiments and water immersion experiments, to simulate physiological changes. The microgravity environment was found to interfere with signaling pathways in musculoskeletal groups, making cells desensitized to growth maintenance stimuli.
In terms of developing countermeasures, the most effective at present is to simulate gravity load with regular physical exercise. ISS astronauts undergo aerobic and strength training on a specialized exercise program to maintain muscle strength and bone density. In addition, other treatments such as medication, electrical stimulation and nutritional supplementation are being explored.
The problem of musculoskeletal loss in astronauts is complex and urgent, and needs to be solved through multidisciplinary cooperation and continuous research. In-depth understanding of the metabolic changes of bone cells under weightlessness, and targeted exercise and drug intervention can slow down or even prevent musculoskeletal loss, ensuring health and the success of space missions.
While some progress has been made, it remains complex. Current research mainly focuses on the impact of short-term spaceflight, and the challenges of long-term space exploration (e.g., Mars missions) are poorly understood. Future research needs to better understand the physiological changes in microgravity and develop more effective countermeasures to protect the health of astronauts.
Aerospace musculoskeletal loss and astronaut sarcopenia are important health problems in space flight. Through continuous research and innovation, it is expected that better ways to counter the impact will be found and provide a safer environment for astronauts to live and work in space for a long time.