How Protein Builds Muscle After a Workout

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You know that feeling. Your muscles ache from yesterday. You’re feeling weak and puny as you start your next workout. And all your workout friends remind you to keep up with your daily protein intake, but have you wondered what’s going on inside your muscles? How the protein you eat helps you stay in shape, especially after you get hit with delayed onset muscle soreness, also known as DOMS?

The Molecular Basis of DOMS

How Does Protein Build Muscle?

Actin chains are gripped by myosin motors, each motor has long tails that are braided. So, your muscles work like a nanoscopic bungee run. Your springy chain of titin guides your team of myosin motors as they blindly pull their way down the surface of your actin chains, nanometer by nanometer.

Eventually, the force of whatever weights you are lifting balances the force that your myosin can exert. At that point, the bungee run comes to a stalemate. And, like the moment everyone who has ever done a bungee run remembers so well, your myosin motors get yanked back as you consciously allow your muscles to relax and your nerves tell your motors to give up their fight.

If you keep your muscles maximally tensed for too long or for too many reps, your myosin motors can actually get yanked completely out of register. This process is called sarcomere popping, and it makes your muscles sore and unable to lift as much, which are the classic symptoms of DOMS.

Your body attempts to fix this problem by using an actin-cutting protein called gelsolin, which wraps around the actin chain that popped out of place. New actin building blocks get synthesized by your body’s protein factory, which is called the ribosome. Your ribosomes read the genetic recipe written in your messenger RNA.

Once your actin building blocks are in place, which can take a few days, your muscles are back on track for more lifts, curls, squats, presses, and anything else you want to do. Your symptoms are gone, and your muscles are that much stronger and resistant to future bouts of DOMS.

Le Chatelier’s Principle

How does ingesting extra protein help with this process? Obviously, if you had a shortage of amino acids, your ribosomes would not be able to build new proteins. But most of us never even get close to that level of amino acid shortage.

So, to understand how creating a surplus of amino acids works to build muscle faster, we have to turn to a 135-year-old theory called Le Chatelier’s Principle. Not that Le Chatelier’s explains everything, but it’s the chemical principle that your body exploits in order to build more muscle when protein is plentiful. All it says is that when you have a chemical reaction, adding more of the starting reactants causes more of the final products to be formed.

In this case, adding more amino acid reactants causes more protein products to form. It’s that simple. And your body exploits that simple truth to trigger all kinds of amazing, wonderful, and yet-to-be-discovered molecular interactions that amplify and control Le Chatelier’s principle.

The bottom line is that no one knows all of what happens inside the black box of your molecular machinery when you consume more protein, but carefully controlled studies of people ingesting varying amounts of protein have shown that Le Chatelier’s principle works: the more protein you put into your body—up to a certain point—the more easily your body builds back its protein components, such as the actin chains that DOMS disrupts. And that’s a reassuring thought the next time DOMS strikes and you’re feeling a little weak and puny!