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Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey

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Speaker 1: brain Stuff, Lauren Bolga bam here. If you, presumably a human,

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Speaker 1: spent the entire winter snoozing in bed, it's very unlikely

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Speaker 1: that you'd be able to pop out your front door

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Speaker 1: on the first balmy day of spring and run of

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Speaker 1: five K. That's because our muscles have some very specific rules,

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Speaker 1: and one of them is use it or lose it.

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Speaker 1: It makes sense, right Working a muscle lets our body

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Speaker 1: know what's expected of it, So a human muscle develops

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Speaker 1: pretty much exclusively through regular use and good nutritional intake.

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Speaker 1: This is not the case for all animals, however. Take

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Speaker 1: the thirteen lined ground squirrel, a native to the grasslands

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Speaker 1: and prairies of the North American Midwest. This little ground

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Speaker 1: dweller hibernates in the winter, but like most winter sleeping mammals,

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Speaker 1: it wakes up in the spring ready to return to

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Speaker 1: hunting down prey, in this case, grasshoppers, right away, no

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Speaker 1: training period necessary. A study published digitally in January two

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Speaker 1: and the journal Science found that the thirteen lined ground

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Speaker 1: squirrel is able to build some muscle even when it's

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Speaker 1: not getting exercise or taking in nutrients. With the help

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Speaker 1: of a special friend, it's gut bacteria. Researchers in previous

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Speaker 1: studies had noticed that the fat stores the hibernating ground

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Speaker 1: squirrels industriously built up during the summer months began to

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Speaker 1: decline sharply in February, and by the time they shuffled

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Speaker 1: out of their burrows in April, they had lost about

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Speaker 1: forty of their body weight from the autumn before, and

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Speaker 1: the squirrels slept soundly and their body temperatures plummeted to

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Speaker 1: match that of their chilly little burrows, their metabolism dropping

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Speaker 1: to around one percent of what it was in the

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Speaker 1: summer months. However, toward the end of the winter, their

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Speaker 1: leg muscles began to build new tissue. The study in

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Speaker 1: the journal Science set out to discover the mechanism to

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Speaker 1: allow animals that have been cut off from nutrients and

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Speaker 1: movement for several months to still build muscle. The scientists

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Speaker 1: have known for some time that there are ways for

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Speaker 1: a body to create the nutrients needed to create muscle.

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Speaker 1: It's sometimes seen in cattle and other ruminant animals. The

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Speaker 1: process is called urea nitrogen salvage, and it allows the

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Speaker 1: body to retain nitrogen that would otherwise be sent out

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Speaker 1: into the world in the form of urine, and nitrogen

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Speaker 1: is essential to making protein, which is essential to building muscle. However,

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Speaker 1: this process requires something else, an enzyme called urias, which

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Speaker 1: animals cannot produce, but certain bacteria can. The researchers learned

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Speaker 1: that in order to find nitrogen to make protein and

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Speaker 1: build enough muscles so they're behind legs aren't a pair

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Speaker 1: of spaghetti noodles after a long winter's nap, the ground

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Speaker 1: squirrels rely on specific gut bacteria. The bacteria make the

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Speaker 1: urias that helped the squirrels mind the urea in their

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Speaker 1: bodies for nitrogen. The bike grobes benefit too, by using

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Speaker 1: the resulting nitrogen to build proteins that they need. If

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Speaker 1: hearing this makes you interested in whether humans might be

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Speaker 1: able to build muscle without eating or working out, it

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Speaker 1: turns out that we do have the ability, with the

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Speaker 1: help of our gut bacteria, to recycle a small amount

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Speaker 1: of urea nitrogen. The researchers think this discovery might have

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Speaker 1: therapeutic applications to help people stuck in bed due to

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Speaker 1: an illness or injury, or to help astronauts retain muscle mass.

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Speaker 1: While hanging out in space. Today's episode is based on

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Speaker 1: the article Squirrels get jacked during Hibernation No Weights Needed

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Speaker 1: on how stuffworks dot Com, written by Jesslin Shields. Brain

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Speaker 1: Stuff is production of I Heart Radio in partnership with

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Speaker 1: how stuff Works dot Com and is produced by Tyler

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Speaker 1: Klang and Ramsey Young. For more podcasts my heart Radio,

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Speaker 1: visit the heart Radio app, Apple podcast, or wherever you

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Speaker 1: listen to your favorite shows. H