Assessment of Protein Status of Athletes
Although not considered a major source of energy, dietary protein (or more accurately amino acid) intake is important for exercise adaptation. The body functions on a simple scheme of sensing a stress and responding to minimize the disturbance caused by that stress if it is encountered again. As far as exercise and performance are concerned, the stress is designed to make the body better able to run, jump, throw, etc. The way the body-or more accurately, the individual cells-adapt to the stress is to increase the making of proteins that provide the metabolic and structural support needed to adapt to the stress. Simultaneously, proteins that might not be needed are broken down because they are energetically expensive to maintain. The turnover of proteins, which is dictated by gene expression in response to stress, determines the phenotype of the athlete. Important to this chapter is that the making of proteins requires amino acid building blocks and energy, which are consumed in the diet.1 In a broad sense, then, we need dietary amino acids to help make the proteins that the cell requires to adapt to an exercise stimulus.