The two ingredients that can be considered the powerhouses of bodybuilding are creatine and leucine. Each has been found to be synergistic in its ability to build muscle and prevent muscle tissue breakdown.
Creatine has been found to result in increases in muscle mass and strength. Some of the possible physiological causes of the increase in strength and muscle mass are: increases in high-energy phosphate metabolism, satellite
cell activity, cellular hydration status, and hormonal adaptations (i.e., insulin-like growth factor
Leucine is an amino acid of special interest because it stimulates muscle protein synthesis and inhibits protein breakdown, suggesting that it is highly anabolic. The cascade of events that lead to anabolic activity is mediated through the mTOR pathway, resulting in increased muscle protein synthesis and muscle mass.
The anabolic effects of mTOR on protein synthesis were completely abolished in the presence of rapamycin, an mTOR inhibitor. For several years, branched chain amino acids were advocated pre-workout, but taking leucine may be the only amino acid necessary as muscle protein stimulation is responsive to stimulation by leucine, but not the other branched-chain amino acids, isoleucine and valine. Leucine seems to be the most potent of the BCAAs with regard to most of these effects, and therefore may be the most physiologically relevant. Leucine alone can substitute for a meal in stimulating signal transduction pathways, leading to a stimulation of protein synthesis. Large oral leucine dosages increased muscle protein synthesis within 20 minutes, similar to meal feeding. The activity of the mTOR-signaling pathway in muscle is augmented following the oral leucine consumption. Keeping mTOR turned “on” is the key to building muscle mass, whereas when mTOR gets turned “of ,” it’s catastrophic for muscle growth.
- FLEX
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