７７ Aging in Space

７７　Aging in Space【Space Travel】Dialogue with the Universe

○In the universe aging progresses ten times. [1]
：decreased muscle strength, bone density, circulatory function and immunity, abnormal lipid and sugar metabolism
・After a certain age, people on Earth start to lose mass in their bones, typically at a rate of about 1-to-2 percent a year. But in space, those people lose bone mass at a greatly accelerated rate: as much as 1-to-2 percent a month.

Image credit: NASA

○Cause of aging: weightlessness and otolith
・In the zero gravity state, abnormality occurs in the otolith (connected with autonomic nerves and muscles of the whole body).
・Luckily, skeletal systems of the astronauts usually return to normal once they've spent some time back on terra firma.[1]

※Otolith [2]

○Sitting disease: If you keep sitting for an hour, your life expectancy will shrink by 22 minutes because the otolith will not move. [3]
：decreased muscle strength, bone density, circulatory function and immunity, abnormal lipid and sugar metabolism
⇒Increased risk of genetic diseases, cancer, diabetes, heart disease, autonomic nervous disorder.

○Countermeasure: Stand up once every 30 minutes. (32 times a day) [4]
・Otolith moves when standing up rather than walking.

【References】
1. Jessika Toothman ”How do humans age in space?” at SCIENCE 
http://science.howstuffworks.com/humans-age-in-space.htm/printable
2. Biodun Olusesi “Searchlight on Otoliths!”at Interesting ORL Facts 20130618
http://iofacts.blogspot.jp/2013/06/searchlight-on-otoliths.html
3. “IS SITTING KILLING YOU?”at ClickFit 
https://www.clickfit.com/health-library/healthy-living/is-sitting-killing-you/
4. Dr.Mercola “Sitting Kills, Moving Heals”at Mercola.com 20130723
http://articles.mercola.com/sites/articles/archive/2013/06/23/vernikos-sitting-kills.aspx