Where do Muscles come from?
We hear a lot about muscle protein synthesis (MPS), catabolism, anabolism and amino acids, but what exactly are these things and how do they integrate into the world of strength sports?
To answer that question, we need to discuss the elements of the food we eat and how they relate to energy and building muscle.
The Three Macronutrients and Their Roles in the Body
Fats:
Made of triglycerides which consists of three fatty acids attached to glycerol. Your body either uses dietary fats as energy (slow digesting) or store them as adipose tissue (fat). Dietary fats are not directly stored. They are modified slightly prior to being deposited in adipose tissue.
Besides being a slow-digesting energy source, fats largely contribute to hormone regulation in the body. A diet low in fat can lead to hormone dysregulation, and proper hormone production (Estrogen and Testosterone) is required for protein synthesis and normal organ function.
Carbohydrates:
Made of sugar molecules. These can be simple carbs (sugar) or complex carbs (brown rice). The complexity of the carb is determined by the complexity of the sugar molecules that make up the particular carb source.
Carbs are made of sugar, and sugar (glucose) is our body’s preferred fuel source. Why? Because in the body, glucose drives the production of Adenosine Tri-phosphate or ATP, and ATP the molecular driver of every chemical reaction in the body. From DNA repair to muscle protein synthesis, ATP is required to provide the energy for these normal processes. That being said, without carbs or a diet low in carbohydrates, the body is forced to use other methods of energy, which are less efficient and effective. If you’ve ever been on a low carb diet, especially as an athlete, you know the feeling of fatigue that comes with it; it can be horrible and almost crippling.
Carbs are good, but they too have their limitations. Carbs are NOT directly used to make muscle tissue. If that were the case, then we really would be made of sugar and we would actually melt in the rain.
Carbs are the gasoline for your car. If you have an empty tank, you won’t get very far.
Protein:
Made of amino acids linked together by peptide bonds. Protein can be obtained from many dietary sources, such as meat, beans and vegetables. Ingested protein is broken down into its structural components (amino acids) which are then circulated throughout the body and are used to build other proteins.
Dietary protein is broken down to its amino acid components in the body, and those amino acids are distributed throughout the body and used for protein synthesis. However, protein synthesis does NOT ONLY equal muscle protein synthesis. Amino acids are used to build every protein in your body. From the functional proteins such as DNA repair enzymes to physical tissue, amino acids are the building blocks for every protein-related phenomenon in the body. Whereas carbs are the fuel, amino acids are pieces of metal used to build the engine of the car. You won’t get far without fuel, but you also wouldn’t have a car without the metal to construct the engine, the body, and the interior. It just wouldn’t happen.
Once dietary protein is broken down to its amino acid components and those amino acids are shuttled to your muscles, muscle protein synthesis and muscle repair can occur. It is important to note that if muscle protein synthesis and muscle protein breakdown are dependent upon the amount of total protein consumed. If protein consumption is low, the body will begin breaking down skeletal muscle to create free amino acids to use for other biochemical and bodily functions. If protein consumption is high, then the body will not breakdown skeletal muscle since an abundance of free amino acids are available to use for other biochemical and bodily functions. The trick is determining how much protein you need to stay in a protein net-positive state so that you can spare skeletal muscle and actually grow and repair those muscles.
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