Proteins & Amino Acids
Protein is an essential nutrient in the human diet. It provides a structural and functional role in almost all cells and in particular connective tissue, membranes and muscle tissue. Amino acids are the building blocks of proteins and it is the amino acids that are important to an array of biological functions like growth and repair of the body’s cells. Protein is made up of a collection of 20 standard amino acids. Eight of these amino acids are considered essential (EAAs) as they are not synthesised in the body and so must be supplied by the diet. A further three of these EAAs (namely leucine, isoleucine and valine) are known as the branched chain amino acids (BCAAs) and are strongly linked to muscle growth. Protein can be consumed as a whole source e.g. whey protein, or in free amino acid form e.g. isolated amino acid supplements.
Why are protein and amino acids so important?
Athletes engaged in structured regular training require additional protein in their diet compared to the normal population. Additional protein is required to repair any damage to skeletal muscle cells which can result during frequent exercise sessions. The increase in requirement will be dependent on the type, intensity and volume of exercise completed. Protein and amino acid intake is particularly important prior to and after resistance training to ensure a constant supply of amino acids to the working muscles and to enhance recovery and growth of lean muscle tissue during recovery from exercise. Enhanced recovery and the maintenance or improvement in lean muscle mass is critical to most athletes. In addition, recent evidence shows that protein supplementation enhances fat loss in men and women through its effects on appetite, thermogenesis (burning energy) and the improvement of muscle mass and tone.
Complete and incomplete proteins
All protein sources are not created equally as the amino acid profile varies between sources. There are two differing types of proteins; complete and incomplete. Complete proteins contain all 20 amino acids, these proteins are ideal for aiding muscle growth and supporting performance related goals. Incomplete proteins do not contain all of the eight EAAs, hence the name. Whey protein is an example of a complete protein source, whereas beans and lentils are incomplete protein sources.
Supplementing with a quality protein or amino acid sources like whey, casein, ISO EAA or ISO BCAA is a convenient means of getting the essential amino acids that your body needs for various goals like improving body composition or achieving performance goals like increased lean mass, strength and power.
Branched chain amino acids and essential amino acids in supplement form have been shown to be an excellent nutritional aid for the training athlete. BCAAs and EAAs can help to increase the rate of protein synthesis, decrease the rate of protein degradation and support recovery from training.
Estimated protein requirements for athletes
Protein intake g kg-1 day-1
Moderate intensity endurance athletes
Elite endurance athletes