Is The Post-Exercise Anabolic Window a Myth?

Referencing:

Nutrient timing revisited: is there a post-exercise anabolic window?
Alan Albert Aragon and Brad Jon Schoenfeld

(published in January of 2013)

What is this about?

This study challenges the belief that a specific type or timing of a “recovery meal” is necessary to get the most bang for your buck after a workout.

The researchers approach this by reviewing existing literature on the effects of nutrient timing and reanalyzing the results.

Results

There are several reasons given for eating post workout meals. This study addresses each in its own section, so I will follow suite:

Glycogen repletion

The most common reason given for eating a “recovery meal” is to replace the glycogen lost during heavy exercise.

Glycogen is a type of sugar which our body produces from the food we eat. It is very useful in “explosive,” or short and intense movements, such as jumping, or lifting something heavy. Our muscles can store glycogen within themselves, and can quickly turn it into energy (in the form of ATP) extremely quickly in a process called glycolysis.

There is some evidence that glycogen is also a mediator in intracellular signaling, and has an effect on the rate at which muscles are catabolized (reabsorbed to fuel the body).

Previous research in the field has indicated that:

  • Glycogen has been shown to be a defining factor in protein breakdown, and in reducing catabolism of muscle protein
  • When carbohydrates are consumed immediately post exercise, muscle glycogen is replenished twice as effectively as when the athletes waited to eat for 2 hours.
  • Consuming protein and carbohydrates together enhances glycogen resynthesis, or the process of muscles “filling up” with fuel again.

Aragon and Schoenfield’s thoughts on the matter are that there is not a significant amount of evidence supporting the “anabolic threshold.” Studies have, in their minds, proven that there are very select cases where the timing of eating will affect importance, such as endurance events (long enough to deplete glycogen, generally over 2 hours in duration) that are less than 8 hours apart, or those who train the same muscles more than once a day.

However, there is no evidence that there is any urgency for refueling for the majority of athletes and casual exercisers. 

Protein breakdown

As mentioned in the previous section, muscle catabolism is directly affected by insulin levels, which are almost entirely controlled by ingested carbohydrates. One of the arguments for the importance of eating directly after exercise it to prevent muscle loss. However, science, at this time, does not fully understand the control insulin has on catabolism.

Aragon and Schoenfield point to several studies that prove spiking insulin directly after a resistance training workout has trivial benefits, if any, unless the athlete is in a fasted state prior to the workout beginning.

Protein Synthesis

This, by far, is the most touted reason to have a post-workout meal as soon as possible. However, Aragon and Schoenfield state that there is almost literally no reliable outcomes in studies that address how muscle protein synthesis is affected by post workout nutrient intake. Each study gets a different result, and, in their words:

Thus, the utility of acute studies is limited to providing clues and generating hypotheses regarding hypertrophic adaptations; any attempt to extrapolate findings from such data to changes in lean body mass is speculative, at best.

Muscle hypertrophy

At this point, honestly, you can feel the authors’ blood pressure rising. Throughout the article, they have presented the findings of various studies, and then addressed how the studies were, essentially, worthless, or at least overvalued.

This section is more of the same. The table presented after explaining that each study in the field had a completely different design is all that needs to be restated:

Post-exercise nutrition and muscle hypertrophy

Essentially, there was no conclusive evidence of significant muscle volume changes in between groups.

Their conclusion and advice for practical application

According to Aragon and Schoenfield’s article, there is no conclusive evidence that the anabolic window exists in any significant way except for those most extreme competitive athletes.

Their suggestion to the majority of the population is to instead focus on all around nutrition throughout the day and week. There is some evidence that the preworkout meal is more important, but the studies for that theory are no more thorough than those outlined in this paper.

Advertisements
Tagged , , , , , , , , , , , , , , , , , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: