Protein oxidation exercise effects

Mild exercise produced by swimming rats for one hour decreased protein synthesis by 17. While more intense treadmill running reduced synthesis by 30 and an exhaustive run of three hours inhibited synthesis by 70. These data suggest that exercise may produce a catabolic condition in muscles which would make amino acids available for oxidation and that this effect is dependent on the Intensity and duration of the exercise. 

The impact of aerobic exercise on protein requirements remains uncertain. Exercise clearly can disrupt protein metabolism, both protein turnover and amino acid oxidation. However, it remains to be determined if these effects are acute effects of exhaustive exercise or if moderate exercise in trained individuals still produces increased oxidation of amino acids. 

Aerobic exercise usually increases the percentage of muscle mass due to a decrease in body fat, but produces no absolute change in the amount of muscle. Aerobic exercise has been shown to alter protein metabolism including increases in amino acid oxidation with specific effects on the branched-chain amino acid leucine, increased urinary urea, and increased sweat nitrogen. 

The rate of transport of fatty acids into the mitochondria is determined largely by the availability of carnitine that is used as a carrier. The rate of (3-oxidation is also limited and this is especially pronounced in unfit individuals. One of the beneficial effects of exercise training is that it brings about an increase in the expression of the genes of the proteins of the (3-oxidation pathway. 

Still another study tested the effect of pre-exerdse meals on metabolism and the performance of cyclists. The meals consisted of high fat, high CHO, or high protein 90 min before a weekly exercise test. A CHO supplement was ingested throughout the exercise. The fat oxidation peak rate on the high-carbohydrate meal was half that of the other meals and reduced the fat oxidation across all workloads. However, meal composition did not have a clear effect on performance. ... 

In contrast to endurance exercise, acute whole-body resistance exercise does not alter leucine oxidation. In this same study we also did not find an effect of acute resistance exercise on whole-body protein synthesis, either during exerdse or for up to 2 h post-exerdse. We hypothesized that since muscle protein synthesis (MPS) accounted for only 25% of whole-body synthesis, changes in MPS either may be not measurable or would be negated by a redprocal change in the synthesis of another protein, such as one in the gastrointestinal tract. 

Gaine, FC., Viesselman, C.T., Pikosky, M.A. et al.. Aerobic exercise training decreases leucine oxidation at rest in healthy adults, J Nutr, 135, 1088, 2005. Campbell, W.W., Crim, M.C., Young, V.R., Joseph, L.J., and Evans, W.J., Effects of resistance training and dietary protein intake on protein metabolism in older adults. Am J Physiol, 268, El 143, 1995. 

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