Nutrient Timing Part 2: Post-Workout Nutrition

I recently wrote about pre-workout nutrition and how I consider it the most important meal of the day on days that you are training and on the research-based guidelines on how to eat prior to exercise. If you haven’t read this article, but would like to learn more, please check it out here.

While I believe that pre-workout nutrition is the most important meal as it directly effects your training quality and the magnitude of the stimulus you receive from that training, some would argue that post-workout nutrition is the most important. You know what, it would be hard to disagree with them. The point is, both pre- and post-workout nutrition are very important opportunities to take advantage of nutritional strategies that will help you get the most from your training.

The main purpose of post-workout nutrition is to elicit a timely response to the stressors of exercise that will stimulate an optimal rate of recovery and adaptation to our training. To better understand post-workout nutrition, it is important to understand what is happening in our body as a result of training. With high-intensity exercise, we are greatly reducing our internal stores of carbohydrate, known as glycogen. Muscle glycogen and glucose are the predominant forms of energy utilized by our body during high-intensity training with as high as 80% of our energy coming from these sources [1]. A single bout of high-intensity exercise can deplete glycogen levels by as much as 38% [2, 3]. Furthermore, during high-intensity exercise we are causing muscular damage which creates a catabolic environment in which we have significantly increased levels of muscle protein break-down[4]. Despite this catabolic environment, our body is sensitized to carbohydrates and protein providing us for an opportunity to stimulate recovery and adaptation to a greater degree than at other times throughout the day.

Knowing this now, we can see we have three main goals from our post-workout nutrition:

  1. Replenish our bodies muscle glycogen stores that we used up during the training session
  2. Shift our body out of its catabolic state and reduce muscle protein breakdown
  3. Stimulate muscle protein synthesis, encouraging gains in muscular hypertrophy (size) and muscular strength.

Replenishing Muscle Glycogen Stores

It has become common practice to include a high-glycemic meal following exercise to stimulate maximal rates of replenishment in muscle glycogen stores. In fact, consuming a high carbohydrate meal immediately following exercise has been shown to super-compensate muscle glycogen stores and putting off eating by two hours can reduce replenishment by as much as 50% [5]. The reason our muscle can be super-compensated at this time is because the depletion of our glycogen stores stimulates the translocation of a glucose transporter known as GLUT-4 which helps shuttle greater amounts of glucose into our cells to be stored as glycogen. It has also been shown in a study by the man, the myth, the legend, John Berardi, that consuming a combination of carbohydrates and protein stimulates even greater increases in muscle glycogen re-synthesis than carbohydrate alone with other studies finding similar results [6-10].

This, however, is mostly useful to those competing in endurance events or in training that consists of very high volumes and frequency or multiple daily sessions as it has been shown that muscle glycogen levels are naturally restored to normal levels within 8 – 24 hours following a training bout [11, 12]. There are still other benefits of carbohydrate consumption following a resistance training bout, however, the effort to super-compensate muscle glycogen stores is likely only necessary for endurance-based sports or athletes training multiple times per day.

Shifting Out of a Catabolic State and Decreasing Muscle Protein Breakdown

While most people look first to ways to increase muscle protein synthesis, decreasing muscle protein breakdown is another way in which we can potentially increase our net muscle protein and shift our body out of a catabolic state and into a more anabolic state. One of the main ways in which we achieve this goal is by stimulating the release of insulin. Insulin is one of the strongest hormones in our body and is highly anti-catabolic and stimulates the storage of nutrients into our muscle cells including the GLUT-4 pathway we had mentioned earlier [13-16]. As we mentioned recently, carbohydrate-protein combinations stimulate an even greater release of insulin than carbohydrate alone and the amino acids from protein serve as the building blocks of new muscle protein [6-10].

There is some controversy, however, as to whether temporarily decreasing muscle breakdown by insulin contributes to increases in muscle protein accumulation to much of an extent as some studies have found it only plays a minor role. A solid pre-workout meal should leave insulin levels elevated for up to 3-6 hours leaving little point in trying to spike protein synthesis following exercise [17, 18]. This is part of the reason I support a pre-workout meal as the most important meal of the day.

If, however, you couldn’t get a good pre-workout meal in, striving to spike insulin levels may be more appropriate [19]. Furthermore, if your main goal from your training is to increase muscle size and strength, spiking insulin may possibly contribute to that goal further, even if that benefit is relatively small [20, 21].

Promoting Muscle Protein Synthesis, Muscular Hypertrophy (Size), and Muscular Strength

Finally, one of the most important parts of post-workout nutrition is the promotion of adaptation to our exercise by increasing muscle protein synthesis and aiding in the loss of body fat. Protein is a key stimulator of muscle protein synthesis, particularly milk-based proteins due to their high leucine content, with 20-25g of high-quality complete protein shown to stimulate a maximal rate of protein synthesis [22, 23]. Amounts over this amount were not shown to promote further increases in muscle protein synthesis, however, they do not get “peed out” as is a common myth. They merely are used for energy and contribute to the overall amino acid pool in our body. This 20-25g of protein is the typical serving size of 1 scoop in most protein powders.

The two main proteins used in protein powders are whey and casein, both milk-derived proteins. Whey protein has been shown to digest much quicker than casein protein and contributing more to protein synthesis which is important at this time, however, it may also lead to greater amounts of protein oxidation [24, 25]. Casein, on the other hand, digests very, very slowly over a time period as long as 8 hours or more and has a strong effect on reducing protein catabolism over this vast time period which has been shown to lead to even greater amounts of net muscle protein than whey protein [24, 25]. Other studies have also found a greater muscle building effect to a slower absorbing form of protein such as casein [26, 27].

The incorporation of carbohydrates has been found in a few studies to have an increased anabolic effect versus protein alone [28, 29], however, some more recent studies have found no difference [30, 31]. At this point, it is a subject that requires more research to be conclusive. If you goals are to build muscle, however, the additional calories from the carbohydrates alone may help your goals even if the carbohydrates themselves don’t directly contribute to greater rates of protein synthesis.

Finally, a post-workout supplementation discussion would be woefully incomplete without discussing the benefits of including creatine into this meal. Creatine has been shown time and again to stimulate significantly increased gains in muscle strength and size when consumed following high intensity or resistance training exercise [32-41]. Creatine does so through a number of ways including increasing cellular hydration and up-regulating key pathways in muscle protein synthesis [39, 42, 43]. 5g of creatine monohydrate supplementation has been shown to be an optimal amount to incorporate into a post-workout nutrition regimen to promote adaptations in strength and muscular hypertrophy [32].

Bringing It All Together

I know that was a lot of information so I will summarize here below:

  • 20-25g of high-quality protein has been shown to be enough to simulate maximal rates of protein synthesis following exercise with higher amounts not necessary.
  • Protein quality is an important consideration with complete proteins, specifically those derived from milk, such as casein and whey protein, being the best.
  • Slower digesting proteins, such as casein protein, may be more beneficial for building muscle than quicker digesting proteins such as whey.
  • 5g of creatine monohydrate (~1 teaspoon) has been shown to greatly aid in the development of muscular strength and size when taken immediately after training.
  • 50-70g of carbohydrates may be beneficial to those participating in endurance events or multiple daily training sessions or simply those looking to gain weight, however, it may not be necessary for optimal recovery.

Practical Application: What does all this look like?

A protein shake, consisting of 1 scoop of whey or casein or a combination of both along with 5g of creatine monohydrate is an easy way to optimally stimulate recovery and achieve all of these guidelines. The addition of a piece of fruit or two, while possibly not necessary for protein synthesis, can still likely contribute to recovery and, let’s face it, we could all use a little more fruit in our lives. This could also look like 1 cup of Greek yogurt with 1 teaspoon creatine mixed in and berries and honey added on top. By making this one small change to your daily routine, you can achieve greater improvements in strength, muscle size and fat loss, all of which are good things. Try to get this in as close to your workout as possible, but it is not the end of the world if you wait an hour or two, especially if you had a good pre-workout meal.

While these benefits are great, they have been shown to be even greater time and again when paired with proper pre-workout nutrition. To truly promote the best results from your training program, proper pre- and post-workout nutrition must be incorporated. To learn more about pre-workout nutrition, click here.

I hope you all enjoyed this rather lengthy post. Please let me know what you think in the comments below! If you have any questions, or there is a topic you would like to learn more about, please feel free to reach out. I hope you all have a happy and healthy day!

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