Consumption of Certain Nutrients Pre-Exercise and its Effect on Muscle Protein

Researchers have tested different combinations of protein, amino acid and carbohydrate supplements on volunteers undergoing resistance exercise training. This was done to investigate the ability of the supplements to stimulate protein production in muscle cells.  The latest study examined whether consuming amino acids and carbohydrates before doing leg resistance exercises helped in increasing protein production post-exercise, as well as in preventing a drop in muscle protein levels during exercise.  The researchers were unable to demonstrate any marked benefit for exercisers on this regimen, as compared to those who did not received the supplements.

The consumption of supplements during resistance training is quite popular. Such supplementation is believed to facilitate successful muscle growth and enhancement. Several scientific research studies also support this viewpoint. The studies have shown that ingestion of essential amino acids (the basic components of proteins), proteins such as whey and casein, and carbohydrates causes an increase in muscle protein synthesis during short-term resistance training. The researchers in this study attempted to determine the ideal time frame for consumption of these nutrients. In this case, ideal time frame is one which would lead to increased protein production in leg muscles post-exercise. The researchers also tried to identify the cellular pathways that were switched on during the process.

* Researchers selected two groups of 11 people both male and female. Both groups underwent overnight fasting, with one group consuming a prescribed amount of essential amino acids and carbohydrates an hour before exercising, and the other group not being fed anything.
* Each participant completed 10 sets of 10 repeats of leg extension exercises on a Cybex leg extension machine.
* Biopsies of leg muscles and blood samples from the femoral vein and artery of the leg being exercised, and from a hand vein were taken during the pre-exercise, exercise, one-hour and two-hour post-exercise periods.
* Blood samples were tested for levels of blood pH, glucose, insulin, and lactate. Biopsy samples were tested for presence of specific proteins and for changes in total protein synthesis levels.

* Blood flow, insulin levels and glucose uptake in the exercised leg were found to be much higher during the pre-exercise period in the nutrient-consuming group, as compared to the fasting group. Both groups had significantly higher levels of all three factors during the exercise period, as compared to their pre-exercise baseline levels.
* Mixed muscle protein production rates increased dramatically for those on supplements during the pre-exercise period; it decreased to baseline levels when exercising. The fasting group showed a decline in protein synthesis to below baseline levels when exercising.
* At two hours post-exercise, both groups showed a nearly 50 percent increase in protein synthesis levels over the baseline.
* Several proteins that are part of a cell growth pathway were found to be modified in a way that indicated that the pathway was “switched on” in muscle cells during the pre-exercise and exercise periods in the nutrient-consuming group.

Shortcomings/Next steps
Other studies looking at nutrient ingestion just before exercise have produced contradictory results, with increases in muscle protein synthesis compared to control groups. These studies involved protein measurements by indirect methods, unlike the current study. Differences in study design seem to impact the final results and need to be standardized. Additionally, the authors conceded that although they could ease out differences in the protein production and modification profiles between the nutrient consuming group and the fasting group, their study had focused only on short term post-exercise recovery. They felt that analyzing protein levels after longer post-exercise periods would provide them with insights about the extent of muscle growth over time, following the use of supplements.

The current study was conducted by a research group that has published several articles documenting the effects of ingesting combinations of nutrients such as amino acids, proteins and carbohydrates on muscle protein production. Some of their previous research had demonstrated that consuming essential amino acids and carbohydrates after resistance training caused a considerable increase in muscle protein levels. Combined with the results of their present study, one can infer that getting the timing right when it comes to ingestion of nutrients/supplements while doing resistance training would contribute towards increased muscle growth. These results may eventually help fitness enthusiasts in planning their dietary supplementation appropriately.

For More Information:
Essential Amino Acids and Carbohydrates Ingestion before Resistance Exercise Does Not Enhance Postexercise Muscle Protein Synthesis
Publication Journal: Journal of Applied Physiology, June 2008
By Satoshi Fujita; Hans C. Dreyer; University of Texas Medical Branch, Galveston, Texas

*FYI Living Lab Reports Are Summaries of the Original Research.

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