With the increase in sports

nutrition knowledge has come an array of purported performance enhancing dietary supplements. One of the most common, widely used, and studied classes of supplements is protein powders – traditionally whey, casein, soy, or egg. Studies commonly use supplemental forms of protein rather than whole foods, most likely due to greater shelf stability and JNK inhibitor the ease of providing participants with protein powder to be consumed in addition to their habitual diet. Compliance is likely easier to monitor as well (counting empty supplement packets), than when participants are entrusted to cook additional food to achieve a target diet. Determining if increases in protein intake are warranted to promote resistance training gains is the focal point of this review. Answering this question involves addressing two key areas: 1) the level of dietary protein intake that has been shown to provide the greatest results in resistance training studies; and 2) whether or not there is a discrepancy between this

level of protein intake and habitual protein intakes of participants at baseline in these studies. Most studies support the utility of increasing protein intake to promote muscular benefits while resistance training [1–10]. While evidence weighs heavily in this direction, as with most areas, data are not entirely conclusive. Recently we proposed protein spread theory and protein OSI-906 change theory as possible explanations for discrepancies within the protein and Cytoskeletal Signaling inhibitor weight management literature [11].

Whether or not these theories are supported in resistance training studies is unknown. Therefore, the purpose of the present review is to examine our protein spread and change theories in the context of muscle and strength gains from resistance training. Methods Protein spread theory postulated that there must be a sufficient spread or difference in g/kg/day protein intake between groups to see muscle and strength differences. Protein change theory postulates that there must be a sufficient change from baseline g/kg/day protein intake to during study g/kg/day protein intake to see muscle and strength benefits. “Muscular see more benefits” referred to herein are benefits to the following that were greater than control: lean mass gain, lean mass preservation, strength gain, muscle cross-sectional area gain, and fat loss. Keyword searches in the PubMed, Cochrane Central Register of Controlled Trials, and CINAHL databases were conducted up to August 2012 using the search criteria in Figure 1. Along with the database searches, reference lists of four major reviews relating to the subject matter were scanned for additional studies to include [11–14]. Before and after exercise have been identified as important times for mediating the effects of nutrition on resistance training gains [15, 16].