How smart is protein in divvying itself up to worked out muscles?

If you do bicep curls with your right arm all day long, and have a protein shake, is your body smart enough to divert most of the protein to the right bicep, or does it try to equally distribute throughout the body, so tough luck for your right bicep, it only gets a little of it?

Feel free to just tell me what I should be googling to answer this question, I haven’t been able to find an answer.

thanks gang!

Muscles respond to stress and damage. When you do a bicep curl with only one arm, only that one arm is taking damage from lifting too much weight, so only that muscle takes up the new protein. It’s why right-handed people often have stronger right arms. So it’s not really the body being smart, but the muscle going “I need help”.

However, apparently fat does not care about “spot reduction”, or at least not much. Ab crunches can swell your abs, but your diet reduces the fat layer over the abs and everything else.

This discusses why muscles hypertrophy but not the mechanism for protein distribution asked by the OP. Which I don’t understand. So instead let me pose the question a little differently.

Does the body know where the damaged muscles are and shunt protein distribution to them, like waiters bringing food to the people that ordered it?

Or does the body just distribute protein evenly everywhere, and the damaged muscles grab more of it as it goes by, like a conveyor-belt sushi restaurant?

The body, at least during sleep and rest, works toward repairing damaged cells. Therefore, if a muscle is damaged (which is what happens when we work out; we “tear” our muscles), the body repairs these areas first. So, while I’m not sure how protein functions in terms of building muscle, if you’ve worked your right bicep, it definitely does get more attention because of the damage and stress.

I think the misunderstand is: Protein is not stored. If you eat more protein than you body needs to maintain or repair your muscles, the rest just gets burned as fuel or stored as fat.
So, you are not going to become a ripped bodybuilder just by eating a ton of protein.

(Although, like all things having to do with health and exercise, there is some controversy about this).

The muscle damage hypothesis is not well-established. Some people believe muscle damage is irrelevant to hypertrophy. But if we replace “damaged muscles” with resistance-trained muscles (to capture the other potential mechanisms), then I think the answer is, “yes, protein is preferentially distributed to them.”

Specifically, if I understand correctly, the process of resistance training sets into motion a chemical process that allows for amino acids to attach and form new muscle cellls in those muscles, using up more of that protein that the muscles that are simply recovering or maintaining.

Here’s a link to a study on the damage-hypertrophy connection:

I always had the impression that whatever’s in your bloodstream, be it sugar, protein, fat, etc… is basically taken up by whatever cells need it, and in turn, they emit whatever byproducts they have into the bloodstream.

Then those by-products are taken care of by the kidneys or liver, and any leftovers are converted into fat and stored.

So if you work out your right bicep overly much, and it needs protein to grow/repair itself, it’ll just take it from the bloodstream as it goes by.

In that sense, yes, it’s more like the conveyor belt sushi restaurant. The body doesn’t have any means to put more amino acids in the blood vessels that are going to your right bicep, and less in the ones going elsewhere. When you eat protein, it’s broken down into its constituent amino acids in the intestine, which, as is the case with all nutrients you eat, are taken up into the bloodstream and flow throughout the body. Cells that don’t happen to need any amino acids at the time don’t take up any, and cells that need more take up more.

You got basics from Richard Parker. For more info, see the PDF linked to below. If you don’t want to read all of it, see “TYPES OF MUSCLE HYPERTROPHY” starting on page 2857, “CELL SWELLING” on 2861 and “INITIATION OF EXERCISE-INDUCED MUSCLE
HYPERTROPHY” starting on page 2861 which discusses the three primary factors responsible for initiating the hypertrophic response to resistance exercise (mechanical tension, muscle damage, and metabolic stress).

More likely to be converted into glucose (via gluconeogenesis) and stored as glycogen. Amino acids to fat can happen, but is rarer in most conditions.