Proteins are versatile, remarkable, and dynamic working molecules within our cells. Without proteins, life would not exist. The human body utilizes amino acids from protein to construct and maintain muscle and deliver fuel. While physical activity sends a signal to the brain to build muscle proteins, it is critical that the body has access to high-quality protein to supply the essential amino acids to build that muscle.
Muscle protein synthesis begins with amino acids
Physical activity involves repetitive muscle contractions. As muscles contract, they send signals to their individual cells, requesting more of the particular proteins needed for their activity. For the 24 to 48 hours following moderately intensive exercise, muscles must meet the demand for new protein synthesis, as muscle cells are built. During this time, muscles speed up their protein synthesis rate. To meet this demand, it is crucial that the body have access to sufficient essential amino acids. While some are derived from the recycling of proteins already in the body, new amino acids are needed within this critical window of time from quality protein in the diet. Protein synthesis ramps up once the muscle receives essential amino acids. Studies support the notion that essential amino acids delivered to muscle after exercise promote the tripling of protein synthesis for about an hour or two.
The rate of muscle protein synthesis declines after this time window. It is for this reason that a complete protein, such as whey protein isolate, be available for muscles during this critical period of rebuilding. This synergy between physical activity and essential amino acids is indispensable for muscle protein synthesis.
Diversity of protein functions
Amino acids link together in unique sequences to form long strands. The great variety of proteins in the body is made possible by the nearly infinite number of arrangements of the body’s 20 amino acids. Each unique sequence and its structure make a wide variety of different proteins. While some protein strands work in isolation, others group together to gain function. One example, hemoglobin, consists of four associated proteins, each of which grasps iron within the red blood cells. Each individual protein within the body performs a unique task in a particular cell or tissue type. Proteins play roles as diverse as providing structure and movement, building hormones or enzymes, synthesizing enzymes, transporting substances, and maintaining fluid and electrolyte balance.
When the diet is in short supply of protein or a specific essential amino acid, protein synthesis is slowed while the body breaks down its own internal tissue protein. This process serves to liberate amino acids for the body’s most critically important processes. Without enough protein, the life-sustaining activities of the body slowly cease. Consequent repercussions are compromised nutrient absorption, slower growth in children, diminished kidney and brain function, and debilitated immunity.
The human body has a remarkable capacity to build, regenerate, and maintain itself, given the right building blocks. With a daily supply of amino acids to meet the critical threshold, the body can support its critical functions. For athletes concerned about maintaining and building muscle mass, the functional role of protein is of vital importance.