An adequate supply of macro nutrients and micronutrients are required for survival, growth, and development, and for the maintenance of health and well-being throughout life. Regarding skeletal muscle growth, the accretion of protein (primarily contractile) represents one of the primary goals that a select group of athletes (e.g., bodybuilders, powerlifters, Olympic-style weightlifters) aspire towards. Rates of protein accretion (and loss) are a function of the balance between protein synthesis and degradation. An increase in skeletal muscle mass can occur via an increase in synthesis, a decrease in degradation, or a combination of the two. Note that each process is mechanistically distinct. That is, one can occur in the absence of changes in the other.

Nutritional status and the hormonal milieu present in the body have a profound impact on how protein is used (i.e., oxidized, used to make additional contractile or noncontractile protein, etc.). Various supplements have been touted as muscle-builders" based on the notion that they impact protein metabolism, specifically, via an inhibition of protein degradation. Some of these supplements, it is clear, do in fact ameliorate the decline in protein synthesis seen under certain stressful states; however, protein synthesis may also be affected when these supplements are consumed.

A couple factors must be taken into account regarding the degradation of cellular protein? The half-lives of different proteins vary tremendously between and within cells. Also, proteins do not exist within solution intracellularly but are part of distinct structures (e.g., contractile protein, cytoskeleton, etc.) within the cell. If the integrity of each cell is to be maintained, the degradation of various proteins within a cell must be regulated smoothly. Regarding skeletal muscle, there is evidence that myofibrillar and nonmyofibrillar protein are independently regulated. Thus, when examining the existing data on how various dietary supplements affect protein synthesis and degradation, one must remain cognizant of the fact that whole­body protein synthesis and degradation may (or may not) reflect changes in skeletal muscle protein synthesis and degradation.

The supplements that this chapter will cover are those that have been touted as anticatabolic. It would seem plausible that a decrease in protein degradation with no change in protein synthesis should result in the accumulation of extra protein. This of course would be particularly important for athletes involved in the strength-power sports (i.e. bodybuilding, powerlifting, Olympic-style weightlifting, shot put, discus throw, etc.)