“If you want to make gains, you need a protein shake straight after your workout - otherwise, all the work you put in will have been wasted. ”
Sound familiar? If you’ve ever attended a gym or done some research on how to build muscle, you’ve definitely heard this advice. There’s a name for this piece of wisdom straight out of the proverbial fitness gospel; it’s called the “the anabolic window”, which is the supposed window of time (usually described as half an hour) after resistance training in which your body is in an anabolic state (building up muscle and glycogen stores) and therefore primed and ready to make use of any ingested protein. According to many self-proclaimed fitness gurus, neglecting to take in protein during this time will negate most of the work you did at the gym. It sounds intuitively right - but is the anabolic window real, or is it just broscience? And if it is real, is it really as short as the touted 30 minutes? In this article, we delve into the nature of this popular fitness proverb and see what the science has to say about it.
Before we look at the science, let’s break down exactly what the anabolic window is all about.
The idea works something like this: When you’re lifting weights, your muscle fibres become stressed and begin to break down, and your body’s energy stores begin to deplete as your body uses up its glycogen reserves to continue your workout. If your workout is very strenuous, your electrolytes will be out of whack. After your workout, your body goes into a brief state where it is able to both compensate for the damaged muscle and depleted glycogen stores and spike protein synthesis, ultimately creating new, lean muscle mass that would otherwise not be possible.
As it turns out, the first part, which describes the stress and damage to muscles as well as the depletion of the body’s glycogen stores and electrolytes, is 100% true. It’s the latter part where things start to get muddy. While it was once agreed upon that taking in a helping of protein immediately post-workout helped to increase muscle mass, past research suffered from small sample sizes and limited control for confounding variables. Research methods have now improved, and newer studies paint a different picture.
First, let’s tackle the idea that protein intake during the “anabolic window” prevents muscle breakdown. As it turns out, research shows actual protein breakdown in muscle tissue is only very slightly raised after a workout. That means that there isn’t really a necessity to prevent muscle breakdown to begin with, making immediate post-workout protein shakes minimally beneficial in terms of damage prevention.
There is one notable exception, however: training in a fasting state. If you wake up and hit the gym without eating breakfast, for instance, evidence shows that your muscle protein breakdown will be markedly increased, making an immediate post-workout protein shake (along with some simple carbs) very important.
The desire to increase muscle mass is often cited as the #1 reason people feel they need to wolf down protein during the “anabolic window”. The most current and methodically sound studies, however, suggest that while maintaining adequate protein intake over a 24 hour period is important for making gains, immediate post-exercise protein intake is not necessary in order to reap the benefits of your workout.
Take for instance the 2013 data review conducted by researchers Alan Aragon and Brad Schoenfeld for the Journal of the International Society of Sports Nutrition. Aragon and Schoenfeld found that overall, existing research (which included the young, the elderly, fit people, obese individuals and those who do not habitually workout) did not demonstrate a heightened need for protein intake immediately post-workout. To add to that, Aragon and Schoenfeld also noted that glycogen repletion (another benefit touted as exclusive to post-workout protein shakes), while important over a 24-hour period, is not necessary immediately post-workout. Instead, studies indicated that whether you ingest carbs right after a workout or a couple of hours later, glycogen levels a day later will be the same - and as long as your glycogen reserves are nice and full before your next workout, you’re good to go (which again ties into the difference in post-exercise needs between fasting vs fuelled workouts).
If you still aren’t convinced, you can look at more specific research, like the 2012 study done by Erskine, Fletcher, Hanson and Folland for the Medicine and Science in Sports and Exercise journal. This experiment compared increases in muscle volume between two groups of young men, one of which was a placebo group while the other had protein supplementation. This study controlled for both habitual protein intake and level of training, and found that supplementation post-workout did not augment either muscle strength or size relative to the placebo group.
These studies (and more) are available in the references section of this article.
Before you think you’re completely off the hook after a workout, let’s talk about electrolytes.
Your body’s electrolyte balance is responsible for proper transmission of electrical impulses, which are essential for nerve function and muscle contraction. Any kind of fluid loss can throw your electrolyte levels out of balance, so it’s important to keep them in check.
Electrolyte replenishment post-exercise depends on a few different factors, but as a general rule, you’ll want to replenish your body’s electrolytes as soon as possible if your workout is particularly strenuous or long (i.e. you’re sweating a lot or working out intensely for over an hour). Failure to replenish lost electrolytes post-workout can result in dizziness, nausea, confusion, and muscle weakness, spasms, and cramps.
If strenuous workouts are part of your routine, your body will need electrolytes, sugars, and protein to both function optimally and build muscle. Post-workout supplements offer all of these elements in one package, so they’re a convenient and sensible nutrition option – but with the exception of fasted-state workouts and electrolytes following vigorous exercise, there’s no reason to believe that any of these ingredients absolutely must be consumed immediately post-workout in order for you to see benefits, no matter what popular fitness proverbs you might’ve heard.
Aragon, A. A., & Schoenfeld, B. J. (2013). Nutrient timing revisited: Is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition, 10(1), 5-5. doi:10.1186/1550-2783-10-5
Erskine, R. M., Fletcher, G., Hanson, B., & Folland, J. P. (2012). Whey protein does not enhance the adaptations to elbow flexor resistance training. Medicine and Science in Sports and Exercise, 44(9), 1791-1800. doi:10.1249/MSS.0b013e318256c48d
Kumar, V., Atherton, P., Smith, K., & Rennie, M. (2009). Human muscle protein synthesis and breakdown during and after exercise. Journal Of Applied Physiology, 106(6), 2026-2039. doi:10.1152/japplphysiol.91481.2008
Parkin, J. A., Carey, M. F., Martin, I. K., Stojanovska, L., & Febbraio, M. A. (1997). Muscle glycogen storage following prolonged exercise: Effect of timing of ingestion of high glycemic index food. Medicine and Science in Sports and Exercise, 29(2), 220-224. doi:10.1097/00005768-199702000-00009
PITKÄNEN, H. T., NYKÄNEN, T., KNUUTINEN, J., LAHTI, K., KEINÄNEN, O., ALEN, M. . . MERO, A. A. (2003). Free amino acid pool and muscle protein balance after resistance exercise. Medicine & Science in Sports & Exercise, 35(5), 784-792. doi:10.1249/01.MSS.0000064934.51751.F9
Shirreffs, S. M., & Sawka, M. N. (2011). Fluid and electrolyte needs for training, competition, and recovery. Journal of Sports Sciences, 29(sup1), S39-S46. doi:10.1080/02640414.2011.614269 Cancel
Verdijk, L. B., Jonkers, R. A. M., Gleeson, B. G., Beelen, M., Meijer, K., Savelberg, Hans H C M, . . . van Loon, Luc J C. (2009). Protein supplementation before and after exercise does not further augment skeletal muscle hypertrophy after resistance training in elderly men. The American Journal of Clinical Nutrition, 89(2), 608-616. doi:10.3945/ajcn.2008.26626