Protein occurs in all living cells and has both functional and structural properties, accounting for ~15-20% of total body mass. Approximately half of the body’s protein is present as skeletal muscle, but protein is also an important building block of other tissues, including bone, cartilage, skin and blood as well as functional molecules such as enzymes and hormones. Each protein is made up of a special combination of amino acid building blocks.

Protein has been a nutrient of great interest and debate in the world of sports nutrition for many decades. Its role in facilitating muscle building and repair has made it an obvious focus of attention by athletes and coaches. Within scientific circles, there has been lively discussion about the protein requirements of athletes and others committed to daily exercise. This has finally been resolved with the following findings.

• Daily requirements for protein are increased due to a regular commitment to exercise and to support the synthesis of new proteins that accompanies the adaptive response to each workout or event. Indeed, the protein targets for athletes in heavy training are in the range of 1.2-1.6 g/kg body mass daily¹, which is up to double the amount recommended for sedentary populations.
• These recommendations apply equally to endurance, team and strength/power athletes since high level exercise promotes a specific increase in different proteins according to the stimulus of the exercise session.
• Protein targets are now set-in terms of the spread of protein over the day rather than the total protein target, since optimal protein synthesis occurs for at least 24 hours after exercise. Athletes are encouraged to include a small serve of protein rich foods at 3-5 eating occasions each day. For example, three main meals, a post-training snack and a pre-bed or mid-meal snack. Targets of 0.3-0.4 g/kg typically equate to 15-30 g of protein at each meal or snack.
• The highest recommendations for protein (1.6-2.4 g/kg body mass daily) are targeted to athletes who are undertaking weight loss programs. Such athletes usually desire to achieve “high quality weight loss” in which they reduce fat mass but retain muscle mass.²

Protein foods are widely found in the Australian diet and Western eating patterns. Indeed, most athletes easily achieve total daily protein intake targets, even without considering protein supplementation. However, to optimise dietary protein intake, consideration should be given to the quality of protein food choices, and the timing and distribution of protein intake throughout the day.³

Proteins are found in both animal and plant foods with the major sources in the Australian diet being meat, fish and poultry (32%), cereals and cereal-based foods (26%), plus dairy foods (20%).⁴ Since the amino acid profile of animal proteins is closer to that of humans, they are generally considered to be of higher biological value (HBV). Such protein sources typically provide higher amounts of all the essential amino acids, including leucine, which is the amino acid primarily responsible for turning on protein metabolism. Plant based proteins generally have lower digestibility and lower amounts of essential amino acids. However, any negative implications of this may potentially be overcome by simply increasing total protein intake, using an array of plant-based protein sources (e.g. cereal proteins and legumes) to complement their amino acid profiles and/ or blending plant and animal-based proteins sources at a meal.⁵