NASA
Microgravity leaves marks similar to what happens to the body as it ages. Astronauts have learned to recover from the various effects, and their training is being replicated on Earth.
Astronauts are highly well-trained individuals in excellent physical condition. Even so, many return to Earth with difficulty walking and with other limitations — as happened, we learned this week, with Michael Fincke, who, we don’t know why, aboard the International Space Station (ISS).
The truth is that the impact of Space on the human body is profound and reveals valuable clues about aging here on Earth.
What happens to the body in microgravity works like an accelerated version of human aging. The absence of gravity affects muscles, bones, the spine and even balance, replicating changes in a few months that normally occur over decades. This phenomenon makes astronauts a unique model for understanding how we can prevent back pain, physical frailty and loss of mobility.
Since humans began living “up there,” especially with the continued occupation of the ISS since 2000, it has become clear that weightlessness has severe effects on the musculoskeletal system. You bones can lose up to 2% of their mass per monthespecially those that support the body’s weight on Earth, such as those in the legs. Already the muscles can lose up to 10% of their strength in a few weeks and up to 20% in some months, says Simon Evetts, who has worked closely with astronauts for years at .
To counteract these effects, astronauts follow rigorous exercise routines, dedicating about two hours a day of training which include special treadmills, bicycles and adapted resistance machines to the space environment.
One of the main teachings of space medicine is the importance of the deep “core” muscles, often forgotten in training “down here”. These stabilizing muscles, such as the multifidus muscle and the transversus abdominisare essential to keep the spine stable and protected. In microgravity, these muscles weaken significantly, as they are no longer needed to support the body against gravity.
Studies cited by the magazine show that, after six months in space, the multifidus muscle can reduce by around 10% of its size, while the transversus abdominis can reduce by up to 34%. Furthermore, the neuromuscular control of these muscles also deteriorates.
This loss of strength and control contributes to another curious phenomenon: spinal stretching. In microgravity, the torso can increase by more than 6 centimeters, due to the absence of gravitational compression. However, this stretching is often associated with lower back pain, reported by more than half of astronauts during space missions and which can persist for up to a year after returning to Earth.
Post-mission rehabilitation programs focus on reactivating stabilizing muscles through controlled, mindful movements known as motor control trainingwhich unlike traditional bodybuilding training emphasizes continuous, low-intensity activation of deep muscles, often using biofeedback to ensure correct execution.
Innovative equipment, such as FRED (Functional Re-adaptive Exercise Device)were developed for this purpose, allowing you to work your core muscles without heavy loads. At the same time, new approaches such as low-intensity continuous activation (LICA) exercise They seek to keep these muscles active throughout the movement, without the need for conscious effort on the part of the user.
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Interestingly, these techniques don’t just benefit astronauts. Studies show that they can be effective in rehabilitation after prolonged periods of immobilization, in relief from chronic back pain and even postpartum recovery.
Other technologies inspired by space exploration are also being applied to terrestrial medicine. Anti-gravity treadmillslike Alter-G, allow you to reduce body weight during exercise, facilitating recovery after surgery or injuries. Already compressive factslike the Skinsuit developed by the European Space Agency, help simulate the effect of gravity, and promote better posture and muscle activation.
Don’t have machines? Don’t worry
Simple activities like stand during phone calls, use stairs instead of elevators, sit without support on your back or maintaining balance on public transport help activate stabilizing muscles and combat the effects of inactivity.
Furthermore, practices such as Pilateswhich emphasize core strengthening and body control, have shown clear benefits in reducing back pain and improving posture.
Another aspect affected by microgravity is the balance. In space, the brain adapts to the absence of gravitational references, starting to depend more on vision. When astronauts return to Earth, they face difficulties with coordination and balance, and it is common to stumble or exaggerate movements when walking.
To recover these abilities, sensorimotor reconditioning exercises are carried out, which include balance tasks with eyes closed, use of unstable surfaces and coordination training between vision and movement. These methods are also effective in the general population, especially in the elderly, helping to prevent falls and improve spatial perception.
Finally, bone health is also profoundly affected in space. Microgravity alters the balance between bone formation and resorption, making bones more fragile. One of the solutions under study is the low intensity vibrationwhich stimulates bone regeneration and could be used in the treatment of osteoporosis.
