Short answer: It isn't. At least according to a study from Brad Schoenfeld.
It seems opposite to common belief as many talk about the "hour of opportunity," also known as the anabolic window, following a workout. Sounds legit, right? You have one hour to get some protein into your digestive system or else you will lose the potential benefits from the hard work you just put in. Well, not so fast.
Protein timing is a popular dietary strategy designed to optimize the adaptive response to exercise. The strategy involves consuming protein in and around a training session in an effort to facilitate muscular repair and remodelling, and thereby enhance post-exercise strength- and hypertrophy-related adaptations. Despite the apparent biological plausibility of the strategy, however, the effectiveness of protein timing in chronic training studies has been decidedly mixed. The purpose of this paper therefore was to conduct a multi-level meta-regression of ran- domized controlled trials to determine whether protein timing is a viable strategy for enhancing post-exercise muscular adaptations. The strength analysis comprised 478 subjects and 96 ESs, nested within 41 treatment or control groups and 20 studies. The hypertrophy analysis comprised 525 subjects and 132 ESs, nested with 47 treatment or control groups and 23 studies. A simple pooled analysis of protein timing without controlling for covariates showed a small to moderate effect on muscle hypertrophy with no significant effect found on muscle strength. In the full meta-regression model controlling for all covariates, however, no significant differences were found between treatment and control for strength or hypertrophy. The reduced model was not significantly different from the full model for either strength or hypertrophy. With respect to hypertrophy, total protein intake was the strongest predictor of ES magnitude. These results refute the commonly held belief that the timing of protein intake in and around a training session is critical to muscular adaptations and indicate that consuming adequate protein in combination with resistance exercise is the key factor for maximizing muscle protein accretion.
I have always approached exercise and health science with the same mindset, that the human body is far more complex than what most people give it credit for, and that the level of efficiency in which our bodies conduct day to day activities is incredible.
Case in point, I believe that far too many people have this mindset that our bodies, or more specifically, our muscles just break down or deteriorate due to extreme bouts of exercise. Sure, during extreme cases, our bodies become anabolic in nature (the breakdown of muscle tissue) for energy production. This occurs during times of famine or long bouts of exercise without proper nutrition.
Having said all of that, regardless of how intense your workout is, chances are, your body is has more than enough stored energy to complete the task at hand without the need for the body to catabolize your existing muscle tissue.
Well what about all this talk about muscle tearing and tissue breakdown during resistance training?
Once again, yes, resistance training causes micro trauma, tears, and tissue breakdown during resistance training, however that does not mean that those muscle cells just shrivel up and die if you do not drink Muscle Milk within one hour following your workout.
There seems to be some evidential truth about carbohydrate ingestion to replenish spent glycogen stores immediately following an intense bout of exercise, but even then, it is only important if you are planning on continuing on with even more intense exercise or life events later that day. If you have a casual or even slightly difficult day, physically that is, your regular well-rounded diet throughout the day will aid in glycogen replenishment.
Enough about that, however, back to protein synthesis.
So the common misconception is that after an extreme bout of resistance training, your body should be blasted with essential amino acids, found in your common protein shake immediately following exercise. There are even phrases thrown around about like a "1-Hour Anabolic Window."
The fact of the matter is, your body does not complete a difficult resistance training routine and then immediately resort to digesting and breaking down its own muscle tissue due to damages caused by said resistance training. Instead, your body recognizes the damage done to the muscle tissue, and focuses on repairing it throughout the day, assuming you are ingesting enough protein to meet the demands. This study found that your net protein intake was more important than the timing of it.
Basically, don't beat yourself up if you have a busy schedule, do your workout, and then can't get your hands on some protein until a few hours later. Also don't be so focused on special supplements that advertise "Enhanced Recovery" with large amounts of protein in them.
For very active individuals, especially those who resistance train more than a few times per week should aim for at least 0.8-1g of protein for every pound of body weight to prevent muscle loss (catabolism) and to promote muscle growth (anabolism).
Whole, animal protein sources should aways take precedence (whey, meats, dairy, etc.). Vegetarians can absolutely meet their protein needs, but need to compliment plant sources due to plant proteins being incomplete - lacking all of the essential amino acids. Aim to get as much of your daily protein from food first, then supplement as an accessory.
Tyler Robbins B.Sc. CSCS
Director of Fitness
Head of CrossFit