Amino acid metabolism during exercise

Protein and Amino Acid Metabolism During Exercise... 

Specific exercise such as weightlifting can increase muscle mass (9,10). While the potential to develop muscle mass is established, the metabolic changes that lead to these changes remain unclear. Relatively few studies have examined amino acid metabolism during exercise-induced hypertrophy. The primary reason for the lack of information is the absence of a convenient animal model for weightlifting studies. Human studies utilizing nonradioactive, stable isotopes have not yet been done. 

Wagenmakers, A.J., Beckers, EJ., Brouns, F. et al.. Carbohydrate supplementation, glycogen depletion, and amino acid metabolism during exercise. Am J Physiol, 260, E883, 1991. 

Glucose and amino acid metabolism during recovery after exercise. J. Appl. Physiol. 34 838-845. 

Rennie, M.J. and Tipton, K.D., Protein and amino acid metabolism during and after exercise and the effects of nutrition, Anna Rev Nutr, 20, 457, 2000. 

The calorific capacity of amino acids is comparable to that of carbohydrates so despite their prime importance in maintaining structural integrity of cells as proteins, amino acids may be used as fuels especially during times when carbohydrate metabolism is compromised, for example, starvation or prolonged vigorous exercise. Muscle and liver are particularly important in the metabolism of amino acids as both have transaminase enzymes (see Figures 6.2 and 6.3 and Section 6.4.2) which convert the carbon skeletons of several different amino acids into intermediates of glycolysis (e.g. pyruvate) or the TCA cycle (e.g. oxaloacetate). Not all amino acids are catabolized to the same extent... 

Potassium and magnesium aspartate are salts of aspartic acid, an amino acid. They have been used as ergogenics, possibly by enhancing fatty acid metabolism and sparing muscle glycogen utilization or by mitigating the accumulation of ammonia during exercise. ... 

Ahlborg G, Felig P, Hagenfeldt L, Hendler R, Wahren J. Substrate turnover during prolonged exercise in man. Splanchnic and leg metabolism of glucose, free fatty acids, and amino acids. J Clin Invest 1974 53 1080-1090. 

The majority of the energy for endurance exercise is derived from the oxidation of lipid and CHO. As mentioned above, skeletal muscle has the metabolic capacity to oxidize certain amino adds for energy. While it may se n counterproductive to oxidize proteins during exerdse since they serve eitha- a structural or functional role, amino add oxidation may also be required for exchange reactions in the tricarboxylic acid cycle, and this may increase their net utilization. ... 

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