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The Anabolic Window

At some point in the life of a young gym-goer, one of the local gym bros or your favorite Youtube personality has enforced upon you the need to down your protein immediately post-session or risk losing all the sweet gains you just worked so hard for. It seems that in the broscience bible it states that protein consumed greater than thirty minutes post-workout is pretty much worthless, right? I’m not sure who told me first, and I most certainly have a better understanding of nutrition than when I started. So, I took it upon myself to find if there was any truth to the longstanding belief.

Research on the topic of nutrient timing has been abundant in the recent past, and continues into the present. The idea behind nutrient timing is simple – combine the consumption of an optimal amount of protein and carbs in and around a workout with the supracompensatory hypertrophy that happens post workout - resulting in a hypothesized increase in fat-free mass comparatively.

As we know, our muscular glycogen stores are depleted in resistance training bouts, in conjunction with muscle microtearing. The theory is to replace these glycogen stores with controlled and optimized amounts of nutrients to not only replace but increase the reparative and hypertrophic effects of the post-exercise period. However, the research is not definitive in its support of the theory of nutrient timing. Of seven studies analyzed in a meta-analysis by Schoenfeld and Aragon, four found a significant impact of protein and carbohydrate ingested immediately pre and post exercise, while three found no significant difference. There are two main aspects for consideration:

· 3 of the 4 studies showing positive effects of protein included ingestion immediately prior to the session, not limiting to post-exercise consumption alone.

· These studies utilize a fasted state for experimental subjects, a state that most individuals don’t train in.

Why does this matter?

Exercise during a fasted state has been shown to increase protein breakdown – a topic I covered in my discussion on fasted vs. fed cardio. Therefore, it should be no surprise that a study testing for increased protein synthesis concurrent with protein ingestion would find these very same findings when its subjects are inherently in a protein negative state. In short, the pre and post ingestion is simply averting the fasted state. Over an extended period of time, this protein sparing approach would essentially lead to increased muscle mass not from increased hypertrophy but from chronic maintenance of existing musculature.

What about those that don’t engage in Fasted Training?

It is not uncommon in today’s bodybuilding culture to ingest 5-6 meals a day, with anywhere from 1-3 hours inbetween feeding. The reasons for circle back to the broader implementation of nutrient timing. Depending on meal size and macro-nutrient makeup, this meal in most instances could serve as both pre and post exercise meal, due to the overall time for digestion and absorption of nutrients into the blood stream. Tipton and colleagues have shown that the ingestion of up to 6 grams of essential amino acids immediately prior to exercise optimizes blood amino acid levels up to 2 hours post workout. Supported by concurrent studies, these findings would lead us to believe that consumption of protein immediately prior to exercise would negate the need for a secondary intake post exercise.

For those not following a high frequency meal schedule, with a time period of 4-6 hours existing between the last meal and workout bout; this lag in nutrient intake could be significant enough to necessitate a protein/carbohydrate consumption immediately post exercise to negate fasted-state catabolism.

Key Findings

· For those who consume a meal every 1-3 hours, the traditional theory of an anabolic window is redundant at best. Their high frequency nutrient ingestion is sufficient for supracompensatory hypertrophy. Additional protein ingestion immediately post exercise is not detrimental, but not necessary or optimal. These individuals should simply continue following their eating schedule.

· For those training in a fasted state (4-6 hours post last meal), ingestion of a protein/carbohydrate combination is recommended to reduce catabolism of muscle tissue.

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

Tipton KD, Rasmussen BB, et al. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol Endocrinol Metab. 2001, 281(2): E197-206.


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