It is only recently that the causes of oxidative and muscle stress have been defined. During exercise there is a buildup of free radicals. This is called oxidative stress. Free radicals are largely responsible for damage to the muscle cell membrane. Antioxidants such as Vitamin C and E have been shown to reduce free radical buildup during exercise and protect against muscle damage.
Exercise also stimulates cortisol, the body's stress hormone which increases the protein breakdown.
Insulin has been shown to blunt the cortisol rise normally seen during exercise thereby helping maintain muscle protein. Hard exercise can also compromise the immune system making athletes more susceptible to colds and infection. The natural herb, ciwujia as well as the amino acid, glutamine, have both have been shown to stimulate the immune system. Rebuild Muscle Protein Repair of damaged muscle proteins begins immediately after exercise. Insulin stimulates muscle repair by increasing amino acid transport into the muscle.