Is Muscle Protein Synthesis the Same as Growth?

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Fitness supplement and protein powder manufacturers often market an increase in muscle protein synthesis (MPS) from using their products. MPS has, perhaps partly because of this, become a popular term among athletes, bodybuilders, and fitness enthusiasts. While MPS is necessary for muscle growth, it is actually the reaction stimulated by resistance training and protein intake that leads to this desired end goal.

How Muscle Protein Synthesis Works

Muscle protein synthesis is a naturally occurring biological process that helps to repair and build new muscle tissue in response to resistance exercise or nutrition intake. During intense workouts, your muscle tissue breaks down, stimulating amino acids through MPS to repair the damage. When you eat protein, amino acids from these foods are shuttled to your muscle tissue, replacing any muscle protein that was previously lost.

Learning how to effectively stimulate MPS through resistance training and adequate protein intake will help promote lean mass gains, improve muscle recovery and athletic performance, and provide you with more energy. This will be a different process for each individual—one that is based on physical activity, genetic makeup, and food intake.

Protein Balance

Maintaining protein balance plays an important part in MPS for muscle growth. Muscle protein balance itself is maintained through the dynamic process of muscle protein breakdown and muscle protein synthesis.

When your body is in protein balance, no muscle growth or wasting is occurring and you're considered to be in a healthy state of homeostasis. This is typical of most active individuals performing mild exercise and eating healthy.

However, people who engage in regular, intense exercise programs can be at risk for muscle protein breakdown occurring more rapidly than muscle protein synthesis, which can lead to muscle deterioration.

In order to keep muscle protein balance in favor of muscle growth rather than muscle deterioration, proper protein intake regimens are essential.

Regulating MPS With Diet and Supplements

Dietary protein sources supply essential amino acids (EAAs) for stimulating MPS for muscle protein balance and growth. When your muscle cells are depleted of amino acids through intense exercise, periods of not eating, or oxidative stress, consuming foods high in protein helps keep your body in balance. What appears to provide the greatest benefit is consuming essential amino acids (EAAs) throughout the day, especially post-workout.

In a study measuring the MPS response rates over a four-hour period of 48 healthy men who consumed 0, 10, 20, or 40 grams of whey protein isolate immediately after resistance training:

  • MPS was stimulated at a 49 percent and 56 percent greater rate with 20g and 40g whey protein, respectively, compared to ingesting nothing, with no additional stimulation observed with 10g.
  • The 40-gram dose of whey protein also stimulated unwanted amino acid oxidation and ureagenesis, so 20g may be sufficient.

Consuming 20 40 grams of whey protein after whole-body resistance training has also been shown to increase plasma concentrations of the essential amino acids phenylalanine, leucine, and threonine, all of which have been implicated in muscle growth.

A Word From Verywell

Manipulating muscle protein synthesis (MPS) for enhanced muscle development continues to be a challenge. Future studies are recommended to narrow the scope of how exercise and nutrition influence MPS specific to differing exercise modalities, body types, and genders. If you’re considering additional protein intake beyond recommended dietary requirements for muscle growth, have a discussion with your physician or registered sports nutrition expert.

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