Reduced gravity can affect astronauts’ muscle and nerve responses: Here’s how
This question may sound ridiculous to some, but not to an astronaut on the International Space Station (ISS)! In outer space, where gravity is minimal, our muscles (especially the anti-gravity muscles) are underutilized, which can lead to muscle atrophy and changes in structure and properties. of them. In fact, human leg muscles are known to lose mass during a space flight.
How can astronauts avoid these neuromuscular problems?
A team of researchers from Japan led by Dr. Yoshinobu Ohira of Doshisha University, Japan set out in search of answers. The team also includes Dr. Takashi Ohira, who works with Doshisha University and Kindai University, Japan; Dr. Fuminori Kawano, affiliated with Doshisha University and Matsumoto University, Japan; Dr. Katsumasa Goto, from Doshisha University and Toyohashi University SOZO, Japan; and Dr. Hiroshi Kaji from Kindai University. Recently, they were able to study the response of neuromuscular properties to gravity lifting and share research-based insights into how astronauts can avoid neuromuscular problems. in extended space flight. This review — made available online on March 10, 2022 and published in Volume 136 of Neuroscience & Behavioral Biology Reviews May 2022 — written in response to an invitation to ask authors to contribute to a special issue. This issue, titled ‘Space Neuroscience’, celebrates the first human landing on the Moon as part of NASA’s Apollo 11 Moon mission.
The team examined how the morphological, functional and metabolic properties of the neuromuscular system respond to lowered antigravity activities. They looked at human and rodent simulations first and also saw How afferent and afferent motoneuron activity modulates neuromuscular properties. Their review suggests that afferent neuronal activity (involving signals sent from skeletal muscle to the central nervous system during muscle activity) plays an important role in the regulation of muscle and brain function.
Inhibition of muscle actions against gravity leads to the remodeling of sarcomeres (which are the structural units of muscle), leading to a decrease in their number, resulting in reduced force development, which eventually leads to muscle atrophy. . A decrease in the amplitude of the electrocardiograms was also observed in the antigravity muscles, namely the dorsal and longus muscles of the conductor. This suggests that exposure to a low-gravity environment affects not only the muscles, but also the nerves.
No gravity load impairs engine control, is considered poor coordination of antagonist muscles and altered mechanics. Difficulty walking was also observed in the crews after the spaceflight, even though they exercised regularly on the ISS. Astronauts on the ISS are required to use treadmills, bicycle power meters and resistance training equipment to counteract the effects of reduced gravity on the neuromuscular system and protect their physical health. their substance. However, these exercise-based countermeasures are not always effective in preventing some unwanted neuromuscular changes.
Additional challenges may arise when astronauts are exposed to microgravity for six months or more; for example, on the way to or from the planet Mars. Therefore, this assessment has great significance in the field of space research, with particular focus on astronaut health (recommendations mentioned by the authors).
Changes in muscle properties due to gravity loading may be related to reduced neural activity, as well as contraction- and/or tension-dependent mechanical stress. Stimulating the soleus muscle adequately seems to reduce its risk of atrophy. So, during exercise, astronauts should walk or run slowly with rear foot landing (using a bungee cord would also help). Periodic passive insole stretching also seems to be effective.
Thus, information from a single perspective, as discussed in this review, can play an important role in developing appropriate countermeasures against neuromuscular problems for future long-term human space exploration missions. The ISS astronauts will thank the team for sharing these meaningful insights. In the meantime, let’s wish the researchers good luck for their next mission!