Proteins are nitrogen-containing substances that are comprised of amino acids. They form the major structural component of muscle, and other tissues in the body. Proteins are not the primary or a desired source of energy, but during periods of nutrient deprivation they can be used to produce energy. For proteins to be used by the body, they are first degraded to their simplest form, amino acids. There are twenty amino acids identified that are needed for growth and metabolism, and are categorized as either being essential or nonessential. Nonessential amino acids are synthesized by the body and do not need to be consumed in the diet, whereas essential amino acids cannot be synthesized endogenously and must be consumed in the diet. However, there are non-essential amino acids that are considered to be 'conditionally essential' which means that there may be times when obtaining some of these nonessential amino acids becomes vital for maintaining health. Absence of any of the essential amino acids from the diet can limit the ability for muscle to grow or be repaired.Recent studies have examined the pattern of daily protein intake. Moore and colleagues (2012) provided 80 g of whey protein per day to young, resistance trained men who were randomized into three different groups. One group consumed the protein in a pulse fashion (8 x 10 g of whey protein every 1.5 h); another group used an intermediate ingestion fashion (4 x 20 g every 3 h); and the final group consumed the protein in a bolus fashion (2 x 40 g every 6 h). Ingestion occurred following an acute bout of knee extension exercise (4 set of 10 repetitions using 80%1RM). Rates of protein synthesis were significantly greater for the pulse ingestion format compared to the intermediate and bolus formats (32% and 19%, respectively). Further inferential analysis showed likely small and moderate increases in whole-body protein turnover for the pulse and intermediate ingestion formats compared to the bolus ingestion format. Thus, the pattern of protein ingested appears to impact whole-body protein metabolism. Areta and colleagues (2013) using the same research methodology as the previous study reported that all three ingestion protocols increased myofibrillar protein synthesis, throughout the 12 h recovery period (ranging from 88% - 148%). However, the intermediate ingestion pattern elicited the greatest levels of myofibrillar protein synthesis than the other two ingestion patterns. Thus, it does appear that protein ingestion every three hours has the potential to maximize muscle mass development.
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