Insulin: To Spike or Not to Spike?

Post-exercise nutrition is critical for maximum gains


Post-exercise nutrition is critical for maximum gains. The stimulus of training triggers signaling pathways within muscle cells that allows for greatly enhanced muscle protein synthesis rates. These pathways do not stay active for long, however. There is a window of opportunity immediately post-exercise in which one can significantly increase the anabolic effects of ingested nutrients. This window stays open for a couple of hours at most. After that, the impact of nutrient intake on muscle protein synthesis gradually declines. The more “trained” you are, the faster the anabolic sensitivity dissipates.

The obvious question for most at this point is, “What nutrients will allow me to best take advantage of this anabolic window?” It has been known for many years that protein, or more specifically amino acid availability, is critical to maximize the effects of your post-workout feeding. What has also been recommended is that you ingest a high glycemic–index carbohydrate along with your protein. This would not only replace glycogen used during your workout, but also create an insulin spike that would presumably enhance protein synthesis. After all, insulin is an“anabolic” hormone.

Over the years there have been many studies performed to illustrate the importance of timing post-workout protein and carbohydrate intake.Surprisingly, there have been only two studies looking at the true influence of carbohydrates and/or insulin in combination with protein on the rate of muscle protein synthesis post- workout. After all, it seemed obvious that you needed an insulin spike to maximize protein synthesis. If we take a look at those two studies that did question the importance of adding high-glycemic carbs to post-workout protein drinks, what we find might surprise you.

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