Is there truth to the post exercise carb up with protein window dogma we’ve been doing all these years? Maybe it’s time to break away from the ‘bro-science’ doctrine. Here’s what you need to know… First, amino acid uptake into muscle cells (i.e. right after training) is not exclusively dependent on glucose intake→insulin transport to cells. There are other potential carriers (active transport) for amino acids. Growth Hormone is one. Growth Hormone is stimulated by an acute accumulation of lactic acid (broken down into lactate + hydrogen ions) during bouts of intense/acute exercise. The presence of GH (endogenous) stimulates the secretion from the liver of these small protein hormones called insulin-like growth factors (particularly IGF-1) . These IGF’s are functionally and structurally very similar to insulin. But IGF-1 is actually more potent than insulin in active transport of amino acids across muscle cell membranes. The interesting thing is Growth Hormone release is muted when glucose (and concomitant insulin) is present in blood.
Interesting because we have always been under the idea that the combination of carbs (sugars) with a protein source ingested after a training session would optimize both glycogen repletion and amino acid uptake to help recover from training and rebuild muscle cells (tissue). In fact it may be more advantageous to not include carbohydrates in that first meal after training. There is evidence that at some point glucose uptake post exercise can desensitize the muscle cells to sufficient amino acid uptake and actually decrease protein synthesis. Not good when your trying to put on some muscle. It’s true that a post workout sugar hit with protein may still be somewhat effective. But is ‘somewhat effective’ what we’re looking for? Here’s a recommendation→ 40grams of whey protein isolate soon after a training session seems to be a solid place to start. There is new research that suggests that a bit more might even be a bit better.
Carbohydrate does not augment exercise-induced protein accretion versus protein alone https://www.ncbi.nlm.nih.gov/pubmed/21131864/
Nutrient timing revisited: is there a post-exercise anabolic window? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3577439/
The Role of Post-Exercise Nutrient Administration on Muscle Protein Synthesis and Glycogen Synthesis https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761704/