The following is an excerpt from a cycling nutrition website. I am a long distance cyclist, and need protein to prevent muscle breakdown and for fuel. This website suggests that whey is better for recovery, and that soy is better while on this bike. I need some nutritional gurus to help solve this puzzle.
The Benefits of Soy Protein
Soy protein is best used prior to and during exercise, primarily because it has less potential for producing ammonia, a primary cause of muscle fatigue. For general health benefits it’s hard to beat soy.
Also, as mentioned in the “Proper Caloric Intake” article, soy protein has a unique amino acid profile that suggests it’s the ideal protein to use during endurance exercise. Soy protein is stacked with a substantial proportion of branched chain amino acids (BCAAs), which your body readily converts for energy.
BCAAs and glutamic acid, another amino acid found in significant quantity in soy protein, also aid in the replenishing of glutamine within the body without the risk of ammonia production caused by orally ingested glutamine. Soy has high amounts of histidine, which is part of the beta-alanyl l-histidine dipeptide known as carnosine, which has antioxidant/acid buffering benefits.
Soy protein also has a high level of aspartic acid, which plays an important role in energy production via the Krebs cycle. Lastly, soy protein has higher levels of phenylalanine than does whey, which may aid in maintaining alertness during extreme ultra distance races.