In resting conditions, higher amino acid concentrations in plasma have a stimulatory effect on protein synthesis. Immediately after exercising, this effect of increased availability of amino acids on protein synthesis is exaggerated compared with the resting condition. Among the amino acids, essential amino acids (EAAs) are primarily responsible for the regulation of muscle protein synthesis. Leucine, in particular, plays an important role in that process. Calcium β-Hydroxy-β-methylbutyrate-monohydrate (HMB) is a metabolite of leucine that decreases protein breakdown under conditions of physiological stress, in part by modulating the ubiquitin proteasome proteolytic pathway. Several studies have indicated that HMB also stimulates protein synthesis through the activation of the mTOR pathway.
Research involving physically active adults showed that subjects who supplemented with HMB increased their anaerobic power by 54% over training alone. Although leucine offers similar benefits to HMB in increasing protein synthesis, HMB is more potent than leucine for promoting strength gains due to the additional benefit HMB provides in decreasing protein breakdown. Additionally, as approximately 5% of leucine is converted to HMB, consuming 60 grams of leucine would yield 3 grams of HMB.
The Amino 9TM blend of essential and branched-chain amino acids has been clinically shown to boost muscle protein balance by increasing anabolism and limiting catabolism. Supplemental essential amino acids support muscle protein balance more than BCAAs alone. In a human clinical trial with elderly and young subjects, BCAAs were shown to stimulate 22% more muscle protein synthesis (MPS) than placebo. Furthermore, complementing the BCAAs with EAAs resulted in 50% better MPS than BCAAs alone.
Vitamin D3 has a positive effect on muscle protein and energy metabolism and is therefore necessary for healthy muscle function. Glutamine is an amino acid that acts as an essential substrate for GI mucosal cells, immune activity, and storage of muscle glycogen. Therefore, adequate levels of both vitamin D and glutamine in the body may support healthy muscles.
