I heard about the Anabolic Window concept, more than a decade ago, while I was reading the book, Nutrient Timing, and was listening to various authorities on the subject. It seemed quite convincing back then, just like a lot of other myths. But with passing time, the concept was questioned, shaken and interrogated; and ultimately the truth came out.
Protein timing is a strategy being used for some time now to optimize training adaptations. This simple concept has been to consume, primarily supplemental protein in and around training to facilitate muscle repair and thus promote muscle hypertrophy and strength. Earlier studies showed that protein and other nutrient timing is a crucial concept to enhance performance.
The general accepted fact has been of an Anabolic Window (of app. 30-60min) which opens up post workout, during which consuming protein can skyrocket your recovery capability. This timing was highlighted by researchers Ivy & Ferguson, in their 2013 study in the American Journal of Lifestyle Medicine. The researchers also focussed upon the fact that, anabolic response to a resistance training bout is blunted if protein is ingested after this narrow window, thereby impairing muscular gains.
Dietary protein has been considered a crucial component in stimulating muscle protein synthesis, especially when ingested post a resistance training session.
Researchers Candow & Chilibeck, in their 2008 study in the journal Applied Physiology, Nutrition and Metabolism, suggested that, the timing of nutrient consumption is even more important to these adaptations than the quantity of food and macronutrient ratio of the diet. The reason they gave was “Protein or creatine ingestion proximate to resistance-training sessions may be more beneficial for increasing muscle mass and strength than ingestion of protein or creatine at other times of the day, possibly because of increased blood flow and therefore increased transport of amino acids and creatine to skeletal muscle.
An American College of Sports Medicine (ACSM) study in 2006 in the journal Medicine & Science in Sports and Exercise, by Australian researchers Cribb & Hayes, showed that, supplementation timing is an effective strategy that enhances adaptations from resistance training results in greater strength and body composition improvements (i.e., a gain in lean mass and a decrease in body fat percentage) as well as muscle hypertrophy, compared with supplementation at times outside of the workout period.
However, in every study that has investigated the benefit of immediate post-workout nutrition, subjects were fed after completing an exercise session that they had performed in a fasted or semi-starved state. Also, most of these studies were short term studies.
A 2017 study in the Peer Journal by Brad Schoenfeld, Alan Aragon & other researchers, tested the anabolic window theory by investigating muscle strength, hypertrophy, and body composition changes in response to an equal dose of protein consumed either immediately pre- versus post-resistance training (RT) in trained men. Subjects were 21 resistance-trained men recruited from a university population. Participants were assigned to 2 experimental groups: a group that consumed a supplement containing 25g protein and 1g carbohydrate immediately prior to exercise (PRE-SUPP) or a group that consumed the same supplement immediately post-exercise (POST-SUPP). Results showed that pre- and post-workout protein consumption had similar effects on all measures studied. The researchers concluded that, the interval for protein intake may be as wide as several hours or perhaps more after a training bout depending on when the pre-workout meal was consumed.
In an earlier 2013 study in the Journal of International Society of Sports Nutrition, researchers Aragon & Schoenfeld, suggested that, the post-exercise period is often considered the most critical part of nutrient timing. An intense resistance training workout results in the depletion of a significant proportion of stored fuels (including glycogen and amino acids) as well as causing damage to muscle fibres. Theoretically, consuming the proper ratio of nutrients during this time not only initiates the rebuilding of damaged tissue and restoration of energy reserves, but it does so in a supercompensated fashion that enhances both body composition and exercise performance.
However, Aragon & Schoenfeld, suggested that, “while compelling evidence exists showing muscle is sensitized to protein ingestion following a workout, the anabolic window does not appear to be as narrow as what was once thought. Rather, the authors proposed that high-quality protein dosed at 0.4–0.5g/kg of LBM at both pre- and post-exercise is a simple, relatively fail-safe general guideline that reflects the current evidence. For example, someone with 70kg of LBM would consume roughly 28–35g protein in both the pre- and post-exercise meal. Interval for consumption may be as wide as 5-6h after exercise depending on the timing of the pre-workout meal; the closer a meal is consumed prior to exercise, the larger the post-workout anabolic window of opportunity. However, pre- and post-exercise meals should not be separated by more than approximately 3–4 hours, given a typical resistance training bout lasting 45–90 minutes. If protein is delivered within particularly large mixed-meals, a case can be made for lengthening the interval to 5–6 hours.”
In an earlier 2013 study in the Journal of International Society of Sports Nutrition, researchers Aragon, Schoenfeld & Krieger, found that consuming protein within 1h post-resistance exercise had a small but significant effect on increasing muscle hypertrophy compared to delaying consumption by at least 2h. However, sub-analysis of these results revealed the effect all but disappeared after controlling for the total intake of protein, indicating that favourable effects were due to unequal protein intake between the experimental and control groups (app. 1.7g/kg versus 1.3g/kg, respectively) as opposed to temporal aspects of feeding.
On the other hand, a 2003 study in the journal Medicine & Science in Sports and Exercise, by a Finnish research team, led by H.T. Pitkanen, made six healthy men to workout in a fasted state. He found that, during recovery at 60 min after a resistance exercise session, there was no difference in muscle protein synthesis or muscle protein breakdown between the groups, but at 195 min, both muscle protein synthesis and muscle protein breakdown were increased. The researchers concluded that, in fasting conditions, resistance exercise session induces an increase in muscle protein synthesis and breakdown at 195 min but not yet at 60 min of recovery.
A 2009 study in the International Journal of Sports Nutrition & Exercise Metabolism, by J.R. Hoffman & team, examined the effect of 10wk of protein-supplement timing on strength, power, and body composition, in 33 resistance-trained men. Participants were assigned to a protein supplement either provided in the morning and evening or provided immediately before and immediately after workouts. In addition, 7 participants agreed to serve as a control group and did not use any protein or other nutritional supplement. During each testing session participants were assessed for strength (one-repetition-maximum [1RM] bench press and squat), power (5 repetitions performed at 80% of 1RM in both the bench press and the squat), and body composition. A significant effect for all groups in strength improvement was seen in 1RM bench press and 1RM squat. Results indicate that the time of protein-supplement ingestion in resistance-trained athletes during a 10-wk training program does not provide any added benefit to strength, power, or body-composition changes.
Another 2009 study in the American Journal of Clinical Nutrition, by a European research team led by L.B. Verdijk, assessed the benefits of timed protein supplementation on the increase in muscle mass and strength during prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein. 26 healthy elderly men were assigned to a progressive, 12-wk resistance-type exercise training program with (protein group) or without (placebo group) protein provided before and immediately after each exercise session (3 sessions/wk, 20g protein/session). The researchers concluded that timed protein supplementation immediately before and after exercise does not further augment the increase in skeletal muscle mass and strength after prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein.
A 2018 study in the journal Nutrients, by a Brazilian research team led by Hellen Nabuco, investigated the effects of whey protein (WP) supplementation consumed either immediately pre- or post-RT (resistance training) on skeletal muscle mass, muscular strength, and functional capacity in pre-conditioned older women. Seventy older women participated in this investigation and were assigned to one of three groups: whey protein pre-RT and placebo post-RT, placebo pre-RT and whey protein post-RT, and placebo pre and post-RT. The researchers found that, Whey protein supplementation was effective in promoting increases in muscle mass, muscular strength, and functional capacity in pre-conditioned older women, regardless of supplementation timing.
Some studies have suggested that, protein can help to restore glycogen stores in the body. However, this would only happen in situations where muscle glycogen availability limits performance (i.e. longer duration events) and insufficient carbohydrate is ingested to maximise glycogen resynthesis. If you ingest the recommended amounts of carbohydrate, protein will have no additional benefit.
Therefore, there is no concept of a mystical and magical Anabolic Window as such. Having a whey protein supplement post workout is not going to make much of a difference, as long as you are having an adequate protein rich meal 3-6hrs post workout. You will still build the same muscle mass, regardless of the nutrient timing.
No need to fear muscle breakdown, the way supplement companies tell you. Muscle breakdown does happen but not to an extent that you need some immediate intervention to prevent it, like you need a morphine shot, post a bullet wound. There may be an issue when you are working out on a fasted state, but then your intensity would be too low to work out at a higher intensity, if you are working out in a fasted state.
In fact, with the above studies, the pre-workout nutrition looks a tad more important than the post workout nutrition.
With a personal experience of thousands of clients and people from different walks of life, the most important concept in nutrition is not timing. It’s what are you eating (quality), how much are you eating (quantity), why are you eating (emotions and food psychology), and then when are you eating may come in, if the above Why’s are taken care of.