Great question!!! There are tons of old repeated myths regarding these subjects that are continuously parroted with absolutely no understanding of the current state of science on these things. Let me destroy a few of these for you.
MYTH: A single post workout shake is most effective. NO! A single post-workout meal will have minimal impact compared to what can happen if your nutrition is completely optimized. For example pre-workout meals can be 200% more effective for stimulating muscle growth compared to post-workout (Tipton et al., 2001).
Even more important than the pre-workout meal is the old standard: breakfast. Being essentially fasted for 8-10 hours during sleep can be incredibly destructive for muscle. This is especially true in trained individuals, because we have higher rates of muscle breakdown (Phillips et al. 2002) The faster we can stop this catabolism upon waking, the better. The amount of muscle protein spared from this first meal would be equal to, or even greater, than that gained by a post workout meal. Also, consuming a high quality slow protein before bed, will largely mitigate the catabolic effect induced by nocturnal fasting. Taking this one step further, nighttime eating will actually put your muscle into anabolic overdrive, by supplying even more amino acids to stimulate this metabolic process. Nocturnal feedings, breakfast, preworkout meals, and multiple post workout meals can be more beneficial for muscle growth than a single post workout meal.
Then there’s the suggestion that if we don’t replenish post exercise glycogen right away, we’ll miss a window of opportunity to do so. This is largely hyperbole, exploded from bits and pieces of endurance training studies. One study showed that consuming carbohydrates after strength training only increased muscle glycogen by 16% more than water. (Pascoe et al., 1993) With this information and the huge amount of carbs that we consume on a daily basis, we should have little doubt that glycogen levels will be maximized within 24 hours of the workout. Now these may be irrelevant points, because in the effort of keeping our focus where it ought to lie—on maximizing protein synthesis— we’re going to quickly stimulate our glycogen restoration anyway. This is because we consume rapidly absorbed carbohydrates along with our protein and amino acids, which has been shown to enhance muscle protein anabolism (Rasmussen et al., 2000). In other words, muscle glycogen will be restored whether we make it a priority or not.
Pre workout Nutrition will divert blood flow away from muscles during the workout. This myth actually makes a lot of sense…until you become familiar with the physiology of hormones. Looking deeper, we can find that the insulin stimulated by food intake, actually enhances blood flow and subsequent nutrient delivery to muscles (Coggins et al., 2001).
Applying this principle, liquid pre workout meal consumption dramatically increases muscle blood flow and protein synthesis (Tipton et al., 2001). This elevation in muscle growth is at least twice that observed with the same drink taken post workout (Tipton et al., 2001) This effect even lasts for an hour after the workout, so it’s like having 2 drinks for the price of 1!
MYTH: There’s a one-hour window of opportunity for protein synthesis following a workout. It’s not surprising that with this type of inconsistency that this is probably the most pervasive myth in bodybuilding today! Worse yet, it stems directly from the scientific research itself. The most often cited research on the protein synthetic post workout window, used elderly subjects (Esmark et al., 2001) and cardio exercise findings (Levenhagen et al., 2001) to make their predictions. While this is a completely acceptable practice when these are the only data we have to go on, there are a couple noteworthy problems.
Elderly individuals digest and absorb protein differently than healthy adults. In fact, they digest and absorb whey protein in a similar manner as they do casein (Dangin et al., 2003); in other words they have slow digestion and absorption for whey. Elderly also benefit from having 80% of their daily protein consumed at a single sitting (Arnal et al., 1999), in contrast to the benefits of our multiple feedings.
Additionally, the traditionally referenced Esmark et al. (2001), study showed that consuming the post workout meal just 2 hours after working out actually prevented any improvements induced by the training!
Secondly, with regards to cardio, there’s an obvious difference between how our muscles respond to the two forms of exercise. Bear in mind that with regard to carbohydrate metabolism following a workout, there might not be much of a difference—we just don’t know, but certainly the long-term protein metabolism differences can be seen.
So now what are we supposed to base our nutrition on? Enter the most underrated scientific paper in the last 5 years. Tipton and colleagues (2003) examined responsiveness of protein synthesis for a day after a workout, and found it to reflect a 24 hour enhanced level. This means that having a morning shake will have the same impact on muscle protein synthesis as one consumed following the workout! We’ve known for over a decade that postworkout protein synthesis is jacked up for this long (MacDougall et al., 1995). Some research suggests that even 48 hours after the workout our protein synthesis levels can be elevated by ~33% (Phillips et al., 1997), giving us an even longer period during which we can maximize our muscle growth with protein drinks.
Comparing research that used drinks consumed immediately after a workout (Tipton et al., 2001) versus those ingested an hour after training (Rasmussen et al., 2000), the results are surprising: it seems that post workout meal ingestion actually results in 30% lower protein synthesis rates than when we wait! While we know that our post workout window lasts for at least 24 hours, we can’t assume that the responses to repeated meals will all be the same.
This is where research by Borsheim (2002) comes in. This landmark research shows that the best thing to consume after our post workout meal is… another protein shake! In fact, if we time it right, we’ll get the same huge increase in protein synthesis. Also, you’ll get an even bigger response from the second drink, compared to what you get from the first.