The Anabolic Window

Ah… the anabolic window of opportunity. The ever-claimed period of time post-workout where you, the trainee, have little time to take advantage of your post-workout meal. Fail to do so and you’ll risk ruining all your gains.

Okay, well, that’s not the exact way researchers describe the anabolic window, but it definitely gets the point across. The anabolic window is a coined term used to describe the post-exercise period, as that period of time is the most critical part of nutrient timing.

Getting in ample and sufficient amounts of nutrients in the post-training period is important as it kickstarts the rebuilding and repair of muscle tissue while spiking muscle protein synthesis. Alongside all of this, post-workout nutrition attenuates muscle protein breakdown in the post-workout period, especially in those who may not have had a suitable pre-exercise meal.

But the question remains. Is this window of opportunity really a thing?

Now, as popular as this concept is, there’s actually limited and conflicting research supporting the idea that an anabolic window exists and that it holds any real significance regarding long term muscular adaptations. In order to make our best peri-workout recommendations as coaches, we need context more than anything. This way we’re able to tailor the approach to the individual while taking these findings into consideration.

Let’s first go over the initial goal of nutrient timing

The primary focus of nutrient timing post-workout was aimed at quickly replenishing glycogen stores. The idea here is that we deplete glycogen stores through exercise, so in order to maximize the post-exercise period, we need to quickly replenish our glycogen. Research, however, has shown a stark difference in the need for glycogen replenishment based on the individual and the training they undergo, though.

Long story short, expediting glycogen resynthesis is dependent on the individual and the type of training they participate in (i.e., endurance sports and/or those who need to train multiple times per day). I’ve written an article all about glycogen repletion and this false sense of urgency here which details how this concept has little to no application to those who resistance train as resistance training is shown to deplete only about 36-39% of our glycogen stores.

Muscle protein synthesis

It goes without saying that spiking muscle protein synthesis (MPS) is the most important and most impactful benefit of structuring our post-workout meals. Evidence shows us a profound advantage of supplementing with post-workout protein (with or without added carbohydrates) for maximizing MPS versus supplementing with just carbohydrates alone and/or placebo.

The immediate post-workout meal

With that said, let’s now address the urgency behind this post-exercise window of opportunity. The main misconception we often run into with this window is the idea that we have to consume our post-training meal as soon as possible after exercising.

We’ve all seen those people shaking up their protein shakes in the locker room before they’ve even left the gym. I mean, I’ve even seen someone drinking their protein shake during their workout. Imagine getting whiffs of chocolate milkshake breath while you walk around the gym. Sorry in advance.

Not everyone can accommodate this requirement. Some run straight into work post-training and have a meal soon thereafter, some have a lot more time and can easily make a meal at home, and some may prefer to just eat a whole food meal rather than to drink their protein. This is all realistic and one reason that these findings can help individuals narrow down what they actually need to place their energy towards (and what they don’t need to stress about).

The research

A large reason for this rationale in the first place is the presumption that training is/would be performed in the fasting state, which would give us a great reason to be on top of the post-workout window more than we would, had we eaten a meal beforehand. Training in itself is a catabolic process (damaging muscle fibers, stress on the body, etc.), so training in a fasted state would require us to prioritize the post-workout period in order to push us out of a catabolic state and back into an anabolic one. To ultimately promote MPS and reduce proteolysis.

The current literature available on the “anabolic window” is lacking evidence to support the practice of consuming protein as soon as possible post-exercise. (1) Findings tend to be contrasting and inconsistent more than anything and lack any indication that a specific timing is ideal for maximizing MPS in the post-workout period.

More specifically, one study that stands out comes from Hoffman and colleagues (2009) where they randomly assign resistance-trained males to receive a protein supplement in either the morning and evening, or immediately pre- and post-workout. After the study period, no significant differences were identified regarding lean body mass and body mass.

Practical applications

It goes without saying that getting a sufficient amount of protein in post-workout is important; we have a lot of support for supplementing with protein in the post workout period! The timing and urgency for said protein, though, is where we have more flexibility based on context (not training fasted, the amount of time between your pre-meal and training period, type of training being performed, frequency of training sessions per day).

With that said, the overall approach to post-training nutrition shouldn’t go without some sort guidelines and general recommendations. We don’t want to choose not to eat just because we know that an anabolic window isn’t forcing us to; the post workout period is still important for trainees to maximize if you have physique-, performance-, or fitness-related goals.

Our best suggestions for approaching post-workout nutrition would be to get a high-quality source of protein and some carbohydrates within your post-workout period (ideally no more than 1-3 hours post). Context will matter, of course, but these are reliable guidelines that can apply to most resistance-training individuals looking to maximize their training and improve body composition.

References:

1. Aragon, A.A., Schoenfeld, B.J. Nutrient timing revisited: is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition. 2013, 10:5.

2. Hoffman J.R, Ratamess N.A, Tranchina C.P, Rashti S.L, Kang J, Faigenbaum A.D. Effect of protein-supplement timing on strength, power, and body composition changes in resistance-trained men. Int J Sport Nutr. Exerc. Metab. 2009, 19(2):172–85.