eli5: If working out a muscle causes a pump that increases volume in the muscle, where does the added volume come from?

Question

Given the blood’s volume is oretty close to constant in the shirt term, does the rest of your body lose volume as certain muscles get “pumped”?

In: Biology

Answer 1

The added volume is the “repairs” that’s done when you tear a muscle. It’s a combination of proteins and fats. That’s how the muscle grows – through repeated tears and repairs the body does, when you lift weights especially, to enable you to lift the same weight the next time.