The human body is in a state of constant “training” due to gravity: whether walking or sitting, muscles work to hold the body upright. When this load disappears, a rapid loss of muscle mass begins.
Scientists describe this process as a “dialogue” between cells and gravity. At its core lies mechanotransduction, a mechanism that converts mechanical signals into biochemical reactions.
What happens in weightlessness
According to NASA, astronauts can lose up to 20% of their muscle mass within 5 to 11 days without sufficient physical exertion. The muscles in the legs and torso weaken the fastest.
Mitochondrial activity declines, energy production drops, and protein metabolism becomes unbalanced—leading to tissue breakdown outpacing repair.
Medicine and Earth-bound consequences
As reported by Izvestia, the processes observed in space resemble accelerated aging. Muscle and bone loss also occur in older adults and in patients after prolonged immobility.
Even brief physical activity can help slow down atrophy, making early rehabilitation a critical factor.
Outlook and Mars
Researchers are investigating the minimum level of gravity needed to maintain health. On Mars, where gravity is about 38% of Earth’s, it remains unclear whether this level is sufficient to support muscle and bone function.
Technologies for artificial gravity and novel treatment approaches that can mimic the effects of physical exercise are being explored.
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