>12-hour Anabolic Window...Bro

Readers of my blog know that I am not a big fan of broscience. Sure, sometimes broscience can be pretty bang-on with its claims, but for the most part evidential science tells us otherwise.

One of the biggest myths or misconceptions that I hear all the time surrounds the supposed post workout 1-hour anaobolic window. This is certainly one of these things that since it's heard repeated so often, it just seems to be truth. In actuality, and I love Brad Schoenfeld's take on this, rather than calling it a post workout anabolic window, it should probably be called the post workout anabolic barn door.

A recent study in the American Journal of Physiology looked at just this idea:

Pre-sleep protein ingestion does not compromise the muscle protein synthetic response to protein ingested the following morning


Protein ingestion before sleep augments post-exercise muscle protein synthesis during overnight recovery. Purpose: It is unknown whether post-exercise and pre-sleep protein consumption modulates post-prandial protein handling and myofibrillar protein synthetic responses the following morning. Sixteen healthy young (24±1 y) men performed unilateral resistance-type exercise (contralateral leg acting as a resting control) at 20:00 h. Participants ingested 20 g protein immediately after exercise plus 60 g protein pre-sleep (PRO group; n=8) or equivalent boluses of carbohydrate (CON; n=8). The subsequent morning participants received primed-continuous infusions of L-[ring-2H5]phenylalanine and L-[1-13C]leucine combined with ingestion of 20 g intrinsically L-[1-13C]phenylalanine and L-[1-13C]leucine labelled protein to assess postprandial protein handling and myofibrillar protein synthesis in the rested and exercised leg in CON and PRO. Exercise increased post-absorptive myofibrillar protein synthesis rates the subsequent day (P<0.001), with no differences between treatments. Protein ingested in the morning increased myofibrillar protein synthesis in both the exercised- and rested-leg (P<0.01), with no differences between treatments. Myofibrillar protein bound L-[1-13C]phenylalanine enrichments were greater in the exercised (0.016±0.002 and 0.015±0.002 MPE in CON and PRO, respectively) versus rested (0.010±0.002 and 0.009±0.002 MPE in CON and PRO, respectively) leg (P<0.05), with no differences between treatments (P>0.05). The additive effects of resistance-type exercise and protein ingestion on myofibrillar protein synthesis persist for >12 h after exercise and are not modulated by protein consumption during acute post-exercise recovery. This work provides evidence of an extended window of opportunity where pre-sleep protein supplementation can be an effective nutrient timing strategy to optimize skeletal muscle reconditioning.

This research is indicating that the timing of your protein ingestion probably isn't as important as you once thought, and the speed at which you down your shake isn't going to make or break your gainz. Instead, and something that I repeat to my clients time and time again, is focus on hitting your protein goals between the time you wake up and the time you go to bed - around 1g/lb. bodyweight. On top of that, and something that this study is suggesting, is that having some circulating protein in your system during the hours you are sleeping can be beneficial as well.

I would postulate that since human growth hormone spikes when you are sleeping (or more specifically, when you are fasting), it would be extremely beneficial for your body to have some readily-available amino acids for tissue growth, repair, and regeneration during that time. I personally wouldn't worry about the absorption rate of various types of protein either - casein vs. whey. The rate of digestion, followed by the rate of absorption and utilization are actually quite different. The rate-limiting step of protein absorption is based on the protein transports that carry the broken down amino acids from the intestines and eventually end up at the desired site of growth and repair (muscle tissue, for example).

Tyler Robbins B.Sc. CSCS
Director of Fitness
Head of CrossFit