Where does this come from, and can I check it?

Hard efforts burn stored carbohydrate, and depletion coincides with hitting the wall. The figure is taken from NIGMS, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a human body fact?

Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Running low on muscle glycogen brings sudden fatigue

Hard efforts burn stored carbohydrate, and depletion coincides with hitting the wall Working muscle draws on glycogen stored in its own fibres, breaking it down faster than blood glucose can replace it. A trained adult holds roughly 300 to 500 grams in muscle and liver combined. When those stores run low, the effort becomes unsustainable even though fat reserves remain. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NIGMS

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Science trivia

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Tags: exercise, glycogen, endurance

Running low on muscle glycogen brings sudden fatigue: the short answers

Where does this come from, and can I check it?: Hard efforts burn stored carbohydrate, and depletion coincides with hitting the wall. The figure is taken from NIGMS, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a human body fact?: Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.