1) the essential amino acids leucine, isoleucine and valine make up the BCAAs found in many protein supplements
2) leucine is the amino acid most used during exercise so supplementing may allow more glucose generation
3) in strength trained individuals, whole body protein is increased only at a protein intake up to 1.4g/kg/day – protein intake above this will not be any more beneficial
4) to maintain a protein balance (maintain muscle mass), the RDA for sedentary individuals is 0.94g of protein/kg/day
5) endurance athletes should consume protein at levels of 1.2 – 1.4g/kg/day
6) protein synthesis requires a stimulus and a substrate – resistance exercise acts as a stimulus for protein synthesis provided that a substrate (protein) is available
7) supplementation with the leucine metabolite HMB during intensive resistance exercise training has been found to increase strength and deposition of fat-free mass (i.e. muscle)
8) addition of protein to carbohydrate supplements post-exercise aids recovery of muscle glycogen, a ratio of 3 carb: 1 protein is optimal
9) low levels of glutamine that occur during prolonged exercise can impair the function of the immune system, so provision of glutamine may be beneficial for athletes at certain times
10) PROTEIN AND AMINO ACID SUPPLEMENTS ARE NO MORE OR LESS EFFECTIVE THAN FOOD when energy is adequate for gaining lean body mass
So overall, protein and amino acid supplements have their benefits at particular times during intense training. Low protein intake is rare and often only seen in children and adolescents, pregnant women, dieters and vegetarians.
It is more often than not possible for active individuals to obtain their daily protein requirements through a varied, regular diet with good quality protein. However, protein supplements in various forms can provide a more practical way of ensuring adequate and quality protein intake for athletes.