The anabolic window refers to the period of time immediately following an intense workout in which it is believed that muscle tissue has enhanced sensitivity to nutrients such as carbs and protein. This window is believed to be open for approximately 2–3 hours following a workout.
There have been several studies performed over the years demonstrating the existence and potential benefits of this anabolic window. But a recent paper published in the Journal of the International Society of Sports Nutrition raised some important questions about how we think about this window.
The majority of studies showing a strong effect of nutrient timing on post-workout anabolism used untrained subjects. It is well known that untrained subjects respond robustly to almost any training stimulus. In addition, the anabolic effects of protein are more profound in untrained subjects. The use of untrained subjects may exaggerate the benefits of post-workout nutrient intake.
Another issue to be kept in mind is the lack of long-term studies. Most studies consider only the few hours after a single workout. It goes without saying that we are interested not just in what happens after a single workout, but the cumulative effects of months, if not years, of training. In general, the effectiveness of both training and diet decrease over time. Studies that have looked at the effects of consistent post-workout protein supplementation vs. taking it at a later time have shown conflicting results. Not surprisingly, studies using untrained subjects showed that an anabolic window actually exists. On the other hand, studies using trained subjects were less clear, failing to show significant effects.
There is much more to consider when analyzing the research on the anabolic window. Nevertheless, after painting such a skeptical picture, when all evidence is considered as a whole, there is still enough to believe that there is in fact an anabolic window. As a general rule, you should take in .4–.5g protein/kg of body weight immediately after training. It’s true, as with most other aspects of training, that the newer you are to the game the faster your gains are going to come. Nevertheless, if there is anything that I can do, no matter how slight a benefit it may provide, I’m going to do it. If that means chugging down 40g of whey after every workout, even for just a small boost in growth, I’m going to do it. – FLEX