Amino acids and antioxidants help promote post-exercise muscle recovery.
Glutamine and arginine are essential amino acids that help regulate muscle protein balance. They both are natural signals for growth hormone release and play an important role in building muscle. Glutamine plays a role in the immune system and is a precursor of glutathione, an antioxidant that protects cells from free radical damage. Glutamine concentrations are lower in over-trained or chronically fatigued athletes as compared to healthy, trained athletes and non-athletes. Arginine, by increasing muscle blood flow, helps bring available nutrients to muscles to speed recovery and may play a role in immune response. Soy protein has about 30 percent more glutamine and three times more arginine, as compared to whey.
In addition to the amino acids glutamine and arginine, the branched chain amino acids leucine, valine and isoleucine, also are critical to muscle recovery. These amino acids are utilized during endurance exercise to provide energy to working muscles. Leucine, in particular, plays an important role during recovery by signaling key pathways involved in muscle growth and repair. Isolated soy protein and whey protein contain leucine; however, whey is higher in total branched-chain amino acids including leucine.
Antioxidants are increasingly considered vital for optimal athletic performance and recovery. They help reduce oxidative stress caused by free radicals produced during exercise that may contribute to muscle damage and fatigue. This also may impact delayed muscle soreness associated with unaccustomed or intense physical activity. Soy proteins contain many naturally occurring antioxidants, including isoflavones, saponins and copper. Soy protein has been shown to promote increased total antioxidant status as compared to whey protein.
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