Food-First Approach to Enhance the Regulation of Post-exercise Skeletal Muscle Protein Synthesis and Remodeling

Abstract

Protein recommendations are provided on a daily basis as defined by the recommended dietary allowance (RDA) at 0.80 g protein/kg/day. However, meal-based, as opposed to daily, dietary protein recommendations are likely more informative given the role of the daily protein distribution pattern in modulating the post-exercise muscle protein synthetic response. Current protein meal recommendations to plateau post-exercise muscle protein synthesis rates are based on the ingestion of isolated protein sources, and not protein-rich whole foods. It is generally more common to eat whole food sources of dietary protein within a normal eating pattern to meet dietary protein requirements. Yet, there is a need to define how dietary protein action on muscle protein synthesis rates can be modulated by other nutrients within a food matrix to achieve protein requirements for optimal muscle adaptations. Recent developments suggest that the identification of an "optimal" protein source should likely consider the characteristics of the protein and the food matrix in which it is consumed. This review aims to discuss recent concepts related to protein quality, and the potential interactive effects of the food matrix, to achieve optimal protein requirements and elicit a robust postprandial muscle protein synthetic response with an emphasis on the post-exercise recovery window.

Fig. 1

The “leucine trigger” hypothesis. The ingestion of an isolated protein source (e.g., whey) results in a rapid rise in plasma leucine concentrations, which is superior in terms of amplitude when compared to whole food sources of protein, and corresponds to the extent of stimulation of muscle protein synthesis rates [29]. However, we hypothesize that the interaction of non-protein nutritive components with dietary amino acids (food matrix effects) has a direct effect on post-exercise muscle protein synthesis rates. Overall, the leucine trigger hypothesis is probably highly relevant when ingesting isolated protein fractions, but is less applicable towards the muscle protein synthetic response when ingesting whole food sources of protein, especially in healthy adults [33, 35]

Fig. 2

The whole egg matrix is rich in high-quality dietary protein, lipids, vitamins, and minerals when compared to the egg white matrix. While dietary amino acids are the main precursors for protein synthesis, the non-protein components of the whole egg, which are largely contained in the yolk, may have a role in various aspects of the regulation of muscle protein synthesis rates (MPS). These non-protein components include: cholesterol being involved in translocation of mTORC1 to the lysosomes [80], lipids [81], vitamins [82, 83], minerals [84], and other bioactive components [85, 86] serving to facilitate nutrient sensing mechanisms in muscle tissue. Thus, the interaction of nutrients within whole foods to support post-exercise MPS is likely greater than each respective nutrient in isolation. We propose that food matrix effects should be considered when defining optimal protein intakes to stimulate post-exercise MPS and remodeling. mTORC1 mammalian target of rapamycin complex 1, DHA docosahexaenoic acid, miRNA micro-ribonucleic acid, AA amino acids. ¹Indicates vitamin-like nutrient