Muscle atrophy is approximately what percent if exposed to microgravity for more than six months?

Muscle atrophy is approximately what percent if exposed to microgravity for more than six months?

• A. 10%
• B. 20%
• C. 30%
• D. 40%

Answer: (B)

Prolonged unloading in microgravity leads to loss of muscle mass because the muscles aren’t being used against gravity to the same degree. After more than six months, the typical decline in muscle mass is about 20%, especially in the anti-gravity muscles of the legs. This reflects reduced mechanical loading that lowers muscle protein synthesis and increases breakdown over time. Individual results vary and countermeasures like resistive exercise help lessen the loss, but 20% is the most representative estimate for long-duration exposure. Values much lower (around 10%) usually relate to shorter exposures or effective training, while higher figures (30%–40%) would indicate more severe or longer-lasting atrophy than what is commonly observed after six months.

Prolonged unloading in microgravity leads to loss of muscle mass because the muscles aren’t being used against gravity to the same degree. After more than six months, the typical decline in muscle mass is about 20%, especially in the anti-gravity muscles of the legs. This reflects reduced mechanical loading that lowers muscle protein synthesis and increases breakdown over time. Individual results vary and countermeasures like resistive exercise help lessen the loss, but 20% is the most representative estimate for long-duration exposure. Values much lower (around 10%) usually relate to shorter exposures or effective training, while higher figures (30%–40%) would indicate more severe or longer-lasting atrophy than what is commonly observed after six months.