Grizli. Vir: Pxhere.com
Grizli. Vir: Pxhere.com

Why are bears still fit after a sleepy winter?

Imagine sleeping all winter long.

[Your] muscles would lose their strength, there would be bruises on the skin and you’d probably be starving. Well, grizzlies have no problem with all that.

Grizzlies are a subspecies of brown bear living in North America. In a recent study, scientists revealed what helps grizzlies retain their muscles after a sleepy winter.

Grizli. Vir: pxfuel.com
Vir: pxfuel.com

During the winter sleep, or hibernation, bears lose almost a third of their body weight.

Due to slow breathing and heart rate, digestion and urine production are also slowed down. During the winter sleep, bears do not excrete urine and faeces for several months, which is why nitrogen builds up in their bodies.

Nitrogen is a key component of the amino acids that proteins are made of, which muscle is made of.

Scientists have found that bears do not excrete nitrogen from the body during the winter sleep with urine, but that it goes back into the muscles to prevent their breakdown.

Astronavt v vesolju. Vir: pikrepo.com
Credit: pikrepo.com

Muscle loss is problematic for people who are lying down for a long time due to illness.

Also in astronauts who are unable to use their muscles in the weightlessness of space they gradually begin to break down.

Knowing the mechanism of preserving muscle mass could make life easier in space as well as on Earth.


Proteins (or proteins) are made up of amino acids and play very different roles in the body, including being important in muscle building.

Amino acids are molecules of nitrogen, hydrogen, oxygen and carbon, which are the basic building blocks of proteins.

Nitrogen is a chemical element that is found in the atmosphere and is an important building block in all living things. It is excreted in the body with urea or urine.

Points to Consider

  1. How long do you sleep?
  2. Do you know any other animals that hybernate during winter?
  3. Why is good for bears to hybernate during the winter?


The original version of this article was published on January 16th.

English translation courtesy of JL FlannerTotal Slovenia News, an English language website with news from and about Slovenia.


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