Is there an anabolic window?

One of the most controversial issues in the field of sports nutrition concerns the appropriate time frame for the consumption of post-workout beverage. I think the image of a trainee running around finishing his workout with a drink of protein to avoid closing the anabolic window is more popular in the gym.

anabolic window

Anabolic window of opportunity

The idea behind this is that there is a 60-minute time frame after exercise, called the “anabolic window of opportunity”, in which you have to consume protein in order to achieve the maximum muscle anabolism [1]. Some supporters have even reduced this window to only 30-45 minutes after training. However, the practical relevance and validity of the “anabolic window” theory has been questioned and requires a more balanced view.

The lost gains?

There may be some advantages behind the “anabolic window” for maximizing muscle growth. However, there is scientific evidence showing that the importance of protein intake within such a short time frame is not as critical as is often reported [2, 3]. Instead, it is claimed that the “anabolic window” extends beyond 45-60 minutes after training [4].

protein shake

What does scientific evidence say?

The “anabolic window” indicates that delayed protein intake by 1 hour or more after exercise will reduce – or worse – prevent anabolism during recovery. Thus, according to this theory, protein intake 60 minutes or more after a workout can be considered worthless. Or at least slightly beneficial for muscle growth.

The study of supporters

However, the scientific evidence behind this extreme idea is weak. Therefore, the importance of immediate protein uptake after exercise remains open for debate. Proponents of the “anabolic window” theory often cite findings from a study in young men for a 10-week period [5]. In this study, the group of volunteers who consumed protein immediately before and after each workout gained more muscle mass than the volunteers who consumed protein early in the morning and late at night.

Anabolic window

Other newer studies

However, follow up studies didn’t replicate these findings [6, 7]. The interpretation of the conclusions from any study should be considered in the light of factors other than protein timing,. For example, overall nutrition and levels of physical activity may affect the outcome (ie, muscle growth) of interest. Collectively, these findings call into question the importance of immediate post-exercise protein intake for the purpose of muscle growth.

What one, two, what three hours …

In addition, muscle biopsy studies report similar results of muscle growth after eating a basic mixture of amino acids 1, 2, or even 3 hours after exercise [8, 9]. This research clearly shows that the muscle remains sensitive to protein intake over periods of time, beyond the limits usually set by the “anabolic window”. Indeed, the “anabolic window” seems to extend to 24 hours after training, or perhaps even longer [10]. Clearly, the time frame for protein intake should not be limited to 45-60 minutes after exercise.

post workout
Post workout timing

In conclusion:

There is no scientific evidence that protein intake immediately after exercise promotes anabolism more than delayed intake. At present, it is impossible to draw any absolute conclusions about the optimal protein intake for muscle growth. However, it is safe to assume that post-workout protein intake enhances anabolism. But there is no reason to agitate our customers by suggesting them a protein intake in the next few minutes after exercise.


My suggestion:

Theoretically, the “anabolic window of opportunity” remains open for more than 1 hour after exercise. My suggestion is to encourage your customers to look at total protein intake daily. And according to their aim to reach the consumption of the required amount. If their daily routine practically allows them a single dose of protein after training, it is fine. The purpose and essence of this article is to emphatically demonstrate that you do not need to be on the watch every time you finish your workout.

Think smarter, train better… 

References (10)

Ivy, John., et al. “The future of sports nutrition: Nutrient timing.” In: Basic Health Publications.

Witard, Oliver C., Tipton, Kevin D. “Defining the anabolic window of opportunity.” Agro food industry hi-tech 25.2 (2014): 10-13.

Aragon, Alan., et al. “Nutrient timing revisited: is there a post-exercise anabolic window?” International society of sports nutrition 10.5 (2013).

Tipton, Kevin D., Witard, Oliver C. “Post exercise nutrient timing with resistive activities.” In: Nutrient Timing: Metabolic Optimization for Health, Performance, and Recovery (2012): 163-176.

Cribb, Paul J., Hayes, Alan. “Effects if supplement timing and resistance exercise on skeletal muscle hypertrophy.” Medicine and science in sports and exercise 38 (2006): 1918-1925.

Hoffman, Jay R., et al. “Effect of protein supplement timing on strength, power and body composition changes in resistance trained men.” International journal of sport nutrition and exercise metabolism 19: (2009) 172-185.

Burk, A., et al. “Time-divided ingestion pattern of casein-based protein supplement stimulate an increase in fat-free body mass during resistance training in young untrained men.” Nutrition research. 29: (2009) 405-413.

Rasmussen, Blake B., et al. “An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise.” Journal of applied physiology. 88: (2000) 386-392.

Witard, Oliver C., et al. “Increased net muscle protein balance in response to simultaneous and separate ingestion of carbohydrate and essential amino acids following resistance exercise.” Applied physiology, nutrition and metabolism 39.3 (2014): 329-39.

Burd, Nick A., et al. “Enhanced amino acid sensitivity of myofibrillar protein synthesis persists for up to 24 h after resistance exercise in young men.” Journal of nutrition 141.4 (2011) 568-573.

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