How To Optimize Muscle Protein Synthesis Through Strength Training & Diet

Do you go to the gym (or run or go to fitness classes) regularly, yet you don't notice your muscles looking any more toned than before? Well, it's a tough break, but exercise doesn't automatically translate to muscle growth. 

And whether or not you gain muscle, lose it, or maintain what you currently have, depends on the rate of muscle protein synthesis—which is primarily regulated by resistance training and protein consumption.

Muscle tissue is dynamic, and muscle proteins are being broken down and created (simultaneously) throughout the day. 

Muscle protein synthesis 1is the muscle creation side of this equation. During this process, the body incorporates amino acids (aka the building blocks of protein) into muscle tissue to produce new muscle proteins. These can be contractile proteins like actin and myosin, the proteins that regulate those contractions, or structural proteins that aid muscle stability. 

Not quite. For muscles to grow, the rate of muscle protein synthesis has to outpace that of muscle protein breakdown. 

Two main scenarios that drive muscle protein synthesis 5for adults: strength training and protein intake. 

Dietary protein provides the body with the amino acids needed to build proteins. There are 20 amino acids that make up all the proteins in the human body. The body can produce some amino acids internally, but nine amino acids are essential and have to be consumed by the diet. 

Both animal proteins (like meat, fish, poultry, dairy, eggs, etc.) and plant proteins (like tofu, lentils, legumes, nuts, and seeds) provide amino acids.

Animal proteins are deemed complete proteins because they contain all nine essential amino acids. Some plant foods (like quinoa, soy, and buckwheat) are also complete proteins, but most aren't. 

You can still technically get the protein you need for muscle health if you follow a vegan or vegetarian diet. But you need to be very diligent about eating enough (and a variety of) plant foods. 

Protein powders also deliver a concentrated source of amino acids. Whey protein, in particular, is linked to protein metabolism—especially after strenuous exercise6—due to the fact that it's high in the essential amino acid leucine. Research shows that leucine helps initiate and regulate7 muscle-building processes, and it takes about 2.5 grams of leucine8 to stimulate muscle protein synthesis. Most plant proteins do not meet this important threshold.

The exact amount of protein you need is individualized and depends on your age, sex, activity level, muscle mass, and overall health. 

The bare minimum protein recommendation for healthy adults is 0.8 gram per kilogram body weight a day (for someone weighing 150 pounds, that's about 55 grams). 

But to really stimulate muscle protein synthesis, researchers recommend aiming much higher9 for about 1.6 to up to 2.2 grams per kilogram body weight daily. So that same 150-pound person would need about 109 to 150 grams of protein a day. 

When you consume protein also matters. 

Although most people eat the bulk of their daily protein intake at dinner, amino acid researcher Don Layman, Ph.D., previously told mindbodygreen, "The first meal of the day after a nighttime fasting period is the most important for muscle protein synthesis." 

While there are still numerous benefits to cardio exercise 10(like improving heart health and blood pressure), "doing cardio without paying mind to strength training exercises isn't adequate enough to build muscle," says Cording.

Strength or resistance training11 means that you're working your muscles against a force. This resistance is created from body weight, weight machines, or resistance bands. It can also be carrying laundry or children up the stairs. 

This resistance damages the muscle, creating tiny tears in the tissue. And this is actually a good thing. This damage signals repair processes12 to grow the muscle back stronger. 

"It's important to keep in mind that this growth can only happen when sufficient tension is put on your muscles," registered dietitian and certified personal trainer Brianna Frutchey, R.D., CPT, previously told mindbodygreen. 

The American College of Sports Medicine 11recommends including at least two days a week of strength training to work all major muscle groups (including your glutes, hamstrings, back, shoulders, abdomen, etc.).

But the duration of the session, the number of reps, and the degree of resistance will vary by person. "It's important to be intentional with strength training at a level that's appropriate for you," emphasizes Cording.