Glutamine and skeletal muscle

Of the group of 20 amino acids which covalently bonded in linear sequences to form all proteins from the oldest bacteria to the most complex forms of life, glutamine deserves special attention. For many mammals, including human beings, glutamine, especially intermediate metabolism of amino acids of muscle cells, is the most abundant free amino acid in the body and is important in many cell types, playing an important role in a number of essential functions. In high catabolism conditions, such as diseases and exhausting exercise, the synthesis of glutamine does not supply the needs demanded by the organism. In this process, one of the most important sites of glutamine synthesis is the skeletal muscle, not for its synthesis capacity per se, but because it represents at least 40 % of total bodily mass

Amino acid supplementation and impact on immune function in the context of exercise

Moderate and chronic bouts of exercise may lead to positive metabolic, molecular, and morphological adaptations, improving health. Although exercise training stimulates the production of reactive oxygen species (ROS), their overall intracellular concentration may not reach damaging levels due to enhancement of antioxidant responses. However, inadequate exercise training (i.e., single bout of high-intensity or excessive exercise) may result in oxidative stress, muscle fatigue and muscle injury. Moreover, during the recovery period, impaired immunity has been reported, for example; excessive-inflammation and compensatory immunosuppression. Nutritional supplements, sometimes referred to as immuno-nutrients, may be required to reduce immunosuppression and excessive inflammation. Herein, we discuss the action and the possible targets of key immuno-nutrients such as L-glutamine, L-arginine, branched chain amino acids (BCAA) and whey protein