Use of Amino Acids as Supplements for Matching Nutrition, Training, and Rehabilitation-Focusing on Some Questions.

Exercise for improving physical performance or for rehabilitation and exercise for recovering from altered to normal efficiency of muscles, should be matched by adequacy of nutrition, thus supporting increased metabolic needs. Exercise triggers production of energy, and this is followed also by increased production of oxidant molecules, therefore, epigenetic adaptation in cells requires complex modifications, driven by an optimal balance between syntheses and autophagy, maintaining integrity and promoting increased efficiency of cells. Mitochondrial biogenesis, energy production, anti-oxidants systems, protein syntheses, and removal of inefficient structures are all subordinate to the sufficient availability of essential amino acids and they are indispensable to promote, activate, and maintain protein syntheses of all the structures, either contractile proteins or organelles, and related enzymatic systems on which physical efficiency is based. Increased needs or insufficient availability of essential amino acids in specific populations, due to peculiar changes in metabolism behaviors, as described in the training elderly, should be prevented and treated. Also, we are starting to understand the complexity of interactions among nutritional and physically driven activation of protein syntheses, and why only nutritional stimuli are poorly efficient in promoting muscle trophism even if essential amino acids remain indispensable for triggering syntheses. Moreover, the relationship between increased nutritional need and efficiency of immune system consequent to regular training should not be forgotten, particularly in rehabilitation programs for the elderly.