Post-workout nutrition. Pre-workout nutrition. Mid-workout nutrition. Over the last year, you've heard a whole lot about these topics and for good reason. Whether you're a strength or endurance athlete, the correct nutrients before, during, and after exercise can dramatically impact your muscle mass and recovery.
A few weeks ago at the annual Society for Weight Training Injuries Specialists (SWIS) symposium, I gave a 90-minute presentation detailing how skeletal muscle adapts to resistance exercise training. In addition, I discussed how general nutrition as well as pre- and post-workout nutrition could maximize this adaptation. The following article is adapted from that presentation and it's probably the most advanced, comprehensive article T-mag has ever published on the topic.
Put your thinking caps on and let's delve into the details of why you'd better be paying close attention to what you consume around training time.
Skeletal Muscle Adaptation to Resistance Exercise and the Effects of Nutrition
How You Get Hyoooge!
The purpose of this article is to present a case for the importance of nutrition in terms of the adaptation to resistance exercise. My argument, while hopefully light and free of the burdens of complex and intimidating research jargon, is founded on dozens of research studies. Here's what's on the menu:
• Muscle Protein Composition
• Effects of a Single Bout of Resistance Exercise
• Effects of Long-Term Resistance Training
• Muscle Signaling and Protein Turnover
• Interactions Between Training and Nutrition
Let's dig in.
Muscle Protein Composition
When most weightlifters think of muscle protein, protein synthesis, and protein breakdown, they undoubtedly think only of contractile protein. In the world of muscle physiology we call this portion of muscle the myofibrillar protein. However, this preferential focus on contractile protein is a big mistake since muscle protein synthesis and degradation processes are constantly occurring with respect to the other muscle proteins as well. The other muscle proteins include sarcoplasmic protein and mitochondrial protein.
Sarcoplasmic proteins are located in the free fluid portion of the cell and include proteins like the anaerobic enzymes, some structural support units, RNA, receptors, etc. Mitochondrial proteins are located in the mitochondrion – the cell's metabolic machine – and these proteins include the aerobic enzymes, the structural proteins making up the mitochondrion, RNA, and receptors. Each of these proteins are important in the response to exercise and therefore should be recognized.
Effects of A Single Bout of Resistance Exercise
A single bout of resistance exercise is both a catabolic and an anabolic event. The stress on the body is serious, but the mechanism by which the body recovers leads to growth. I want to focus first on the catabolic events induced by exercise, then we'll look closer at the anabolic events.
The Catabolic Events (The Bad Part)
In response to a single bout of resistance exercise, the following catabolic events occur:
Glycogen Depletion – Studies have shown that performing 10-rep sets of biceps curls and leg extensions leads to a significant depletion of stored muscle carbohydrates. One set of biceps curls leads to 12% depletion while three sets of biceps curls leads to 25% depletion. Three sets of leg extensions lead to 35% depletion, while six sets of leg extensions lead to over 40% depletion. A typical bodybuilding workout may consist of many more sets per muscle group and this may lead to even further depletion of muscle glycogen.
Decreased Net Protein Balance – (Protein Breakdown > Protein Synthesis) In a fasted state, muscle protein status is negative. This means that more protein is broken down than is synthesized and that leads to muscle protein loss. Now, when resistance exercise (both moderate and intense) is performed in a fasted state (after an overnight fast or several hours after a meal), protein status drops even more during the few hours following the exercise bout. This means that you're losing even more muscle protein. Although this protein loss isn't all contractile protein, all of the degraded protein must be replenished via protein synthesis when recovery needs to take place.
The question you should be asking yourself at this point is: "If protein status is negative after training, why don't people get smaller and waste away with resistance exercise?" Well, the answer is simple. Although protein status is negative during the first few hours following resistance exercise, this catabolism shifts toward anabolism later on. The body begins to build muscle after a certain point and this protein anabolism seems to peak at 24 hours after the training bout.
Increased Resting Metabolic Rate – After intense resistance exercise, the body's resting metabolic rate increases by about 12 to 24%. Interestingly, the bigger you are, the more muscle you'll damage in training and the more your metabolism may increase.
Increased Blood Cortisol Concentrations – Studies aren't totally conclusive on this point due to the daily variability of the measure (cortisol concentrations fluctuate widely based on the time of day). I believe that the evidence is fairly convincing that intense exercise leads to an increase in this catabolic hormone. Some studies have shown a doubling in cortisol concentrations after resistance exercise.
Acute-Phase Response – The Acute-Phase Response is an immune and inflammatory response that's triggered when muscle is damaged. This process leads to further tissue injury and destruction as well as the production of free radicals.
The Anabolic Events (The Good Part)
In response to a single bout of resistance exercise, the following anabolic events occur:
Increased skeletal muscle blood flow – During exercise, blood is shunted to the working muscle. This is often called "the pump." This blood delivers nutrients to fuel the muscular work.
Increased anabolic hormones – There are short-lived increases in the anabolic hormones GH, Testosterone, and IGF-1 both during and after exercise. However, people have definitely overestimated the significance of these transient increases in hormone concentrations. I hate to commit a mortal sin here, but the endocrine response to exercise probably has little to do with increasing muscle mass. The small, short lived increases in these hormones are far too brief to really affect muscle mass.
Acute-Phase Response – Wait a minute, didn't I include this in the catabolic section? Yes, I did. You see, while the beginning of the acute-phase response is catabolic, later on the response becomes anabolic.
The Acute-Phase Response
After each resistance exercise bout (assuming you've trained like a T-man), you're going to be sporting some muscle damage. This damage is most likely due to the eccentric (negative) component of the exercise and may manifest as large areas of dead or dying tissue. Once this damage occurs, an immune response is launched and this immune response is put in place to try to destroy and dispose of the dead tissue. So far, so good.
However, the immune cells (leukocytes, macrophages, etc) often don't know where to stop and continue to destroy and dispose of undamaged tissue. This is where the catabolism comes in. Now, not only are we missing contractile proteins as a result of the exercise bout (original damage), but we're missing protein that was undamaged during the exercise but destroyed by the immune response (chemical mediated damage).
Thank goodness the destruction stops here. The immune response, after its nasty destructive binge, leads to the activation of satellite cells. Basically, satellite cells are immature nuclei (nuclei contain the cell's DNA) that hang out on the periphery of the muscle cell. When the immune system kicks up, the satellite cells are stimulated to proliferate and move to the site of the injury.
Simultaneously, growth factors from a place outside the cell called the extracellular matrix are brought into the cell. These two things lead to muscle repair. The satellite cells create new proteins to replace the destroyed contractile proteins. In fact, they do such a nice job that the muscles end up bigger and stronger than they were before the bout.
Effects of Long Term Resistance Exercise Training
It's no secret that resistance training leads to increases in muscle size (hypertrophy) and muscle strength. Next, let's discuss how the muscle adapts to this type of training.
There's an increase in the size, number, and strength of myofibrils (contractile/structural protein). As muscle damage is repaired and protein synthesis elevated, a few things occur. First, the old myofibrils (not the muscle fiber itself) split in two, and when they're repaired there are two new contractile units available for growth.
Second, brand new myofibrils are added to the periphery of the muscle cell, leading to a larger muscle cell. Third, the new myofibrils added will be better suited to the demands of the activity. Powerlifting training will lead the fibers to behave more like the fast twitch Type II-B fibers (fastest available) while bodybuilding training will lead fibers to behave more like the fast twitch Type II-A fibers (still fast twitch, but slower).
There's an increase in the size and strength of connective tissue. Myofibrils are contained within muscle fibers and muscle fibers are grouped together to form muscle fiber bundles. A connective tissue sheath surrounds each bundle of muscle fibers within the whole muscle. This connective tissue adapts to resistance training by showing increases in size and strength parallel to the fiber itself.
There's an increase in stored substrate. As a result of training, there's more glycogen (carbohydrate) and triglyceride (fat) storage within the muscle. This makes more fuel readily available for exercise.
There's an increase in muscle-water content. Due to the increased carbohydrate storage (carbohydrates hold about four times their weight in water) and larger fiber size, more water is present in a trained muscle.
There's an increase in muscle enzyme content and activity. As a result of resistance training, there's an increase in the content of the enzymes of the ATP/PC system and glycolytic system.
There's an increase in nervous system efficiency. As a result of resistance training, the nervous system becomes more coordinated and efficient in terms of muscle recruitment/activation and firing frequency.
I hope it's clear that the genetically driven program of adaptation is a sound one. Adaptations occur to make the body more efficient at doing what it habitually does.
Protein Turnover and Muscle Signaling
At this point, I'd like to address a theory I have regarding physiological adaptation. This theory is based on the concept of tissue turnover. As I've discussed before, all tissues of the body go through a regular program of turnover. Most often people talk about skin turnover. We all know that old skin is degraded and dies off while new skin is synthesized to take its place. This occurs more rapidly when we experience some type of tissue injury (like a sunburn). Well, the same holds true for all tissues of the body. The only thing that's different is the rate at which this occurs.
Muscle protein is no exception to this rule. It's constantly being turned over. And turnover is the balance between protein breakdown and protein synthesis. The rate at which this turnover occurs is dependent on your nutritional intake, exercise habits (the damage caused), and genetic programming.
Understand here that this protein tissue turnover is what allows the muscle to adapt. Therefore, the goal should be to dramatically increase your protein turnover rates. Yes, that's right, I want you to increase your protein turnover and this includes protein breakdown! The funny thing is that everyone wants to decrease their protein breakdown with "anti-catabolic supplements," but that's a bad thing. Let me show you why.
When you first begin a training program, your goal is to lift heavy weights and have big slabs of beef hanging from your skeleton. However, at the start, your muscles are certainly weak and small compared to what they will be. So when faced with what you want them to do, they can't do it; they're dysfunctional.
So how do you make a muscle more functional? You destroy it! And that's what training does for you. When you go to the gym, your muscle is inadequate so you lift weights to make it stronger. This process destroys the dysfunctional muscle and signals the cell to synthesize a new protein to take its place. This protein will certainly not be the same as the previous protein. It'll be bigger and stronger, better suited to what it thinks it'll have to do in the future.
But what happens if another bout of exercise doesn't come after that? Well, as the natural tissue turnover process occurs, that strong muscle will be destroyed and replaced by a weaker one. See how it works? The body is constantly re-creating itself by breakdown and subsequent resynthesis based on what you ask it to do. It really is a beautiful system. Let's look at this process in a little more detail.
As I stated, breakdown is always occurring and is necessary for tissue remodeling. This breakdown, in conjunction with extra cellular amino acids (primarily from the diet), helps to expand the intracellular amino acid pool. When the nucleus is stimulated, the DNA contained within undergoes a process called transcription. Transcription is the process by which a specific group of RNA molecules are formed (mRNA, rRNA, tRNA). These RNA molecules are specific for the signal that interacted with the nucleus.
In the second phase of protein making, the RNA units are stimulated by a process called translation. This signal is responsible for the ultimate protein. The mRNA and rRNA units are the "template" or "blueprint" for protein formation. The tRNA units are responsible for picking up the amino acids and laying them down on this template to form the protein. The two phases of protein formation are regulated independently and I want to briefly discuss this.
New data in the research world is beginning to explain how muscles respond to the exercise signal. This is one proposed model. Basically, when eccentric exercise leads to mechanical stress on the membrane (pulls it apart), a series of chemical events occur within the cell. These chemical events form a messenger system that ultimately stimulates the nucleus. This stimulation leads to the formation of specific RNA molecules (transcription) that may, if all the other cellular conditions are right, lead to more muscle protein and a larger muscle. Remember, transcription is only part of the equation. Translation is also required.
Another major signaling pathway in the muscle is the insulin-signaling pathway. This pathway is elegant because once the insulin molecule binds to the cell membrane, it sets in motion two different chemical messenger systems that accomplish three goals. This system increases transcription (DNA formation), increases glucose uptake into the cell, and increases the translation of the cellular DNA into protein. Although there are other pathways that stimulate translation, the insulin pathway is the most important nutritional one.
The insulin-signaling pathway is dependent on nutrients to run properly. Carbohydrates are necessary for insulin release. The amino acid leucine is necessary to run one part of the pathway that stimulates translation, and the essential amino acids are necessary to lay down on the template to form the protein. Ahh, things are all coming together now.
To better remodel your muscle, you need to destroy the dysfunctional protein (keep tissue turnover rates high) and you need to exercise to stimulate the nucleus. This stimulation will lead to transcription or the creation of a specific blueprint for a better muscle. The insulin signaling pathway completes the protein making process by stimulating the translation of the blueprint into a protein. When all this comes together you end up with a muscle more suited to your activity pattern.
The next question most people ask me is, "Do high rates of muscle protein turnover, when synthesis is greater than breakdown, always lead to huge muscles?" The answer is no! What happens to the muscle is dependent on the signal that stimulates the nucleus. If the signal is a weight-training signal, the RNA as well as the ultimate protein formed will lead to big muscles. In this situation, increasing the size and the strength of the myofibrils is the priority.
However, if the signal is an endurance training signal, the RNA formed as well as the ultimate protein formed will lead to more metabolic muscles. In this situation, the priority is an increase in oxygen delivery and consumption. Because it's the exercise signal and not the nutritional signal that determines the adaptation, weightlifters and endurance athletes should have a common goal of increased protein breakdown (destruction of the old protein) coupled with an even higher increase in protein synthesis (formation of a better protein). In my opinion, nutritional needs of the two types of athletes are strikingly similar.
So, I hope I've convinced you that high rates of tissue turnover are important regardless of which type of athlete you are. But knowledge without action is powerless. Next, I want to show you how to do it.
Interactions Between Resistance Exercise and Nutrition
What to Consume to get Hyoooge!
What's the most important nutritional consideration for maximizing the adaptive potential of muscle? The answer: Total daily energy intake.
There are a few requirements for high rates of tissue turnover and they're all dependent on a high energy input. High rates of tissue turnover are very energy expensive so extra calories are needed to run this circuit. You see, your time in the gym is also very energy expensive and so is the hypermetabolism and muscle repair that follows your workout. If the body doesn't get adequate energy supplies (in the form of calories), it obviously can't optimally perform all the functions of exercise, repair, and tissue turnover.
The first system to suffer in this equation will be your tissue turnover rates. If you don't eat enough daily calories, this system will slow down so that less energy is needed and the energy to fuel the workout and recovery is provided by the destruction of tissues. But in this case, remodeling suffers.
Interestingly, this has implications for your body composition/body fat as well as muscle function. The loss of weight isn't always an indicator of inadequate calorie intake. As described above, the body will slow down tissue turnover in response to under eating. Since tissue turnover is expensive, your energy needs decrease and you remain weight stable. However, as mentioned, your tissue remodeling will suffer.
When you increase calories, the first thing to occur will be the increase in tissue turnover rates. This will dramatically raise calorie needs. Depending on your calorie intake, you may end up either losing weight (turnover increases more than calories), remaining weight stable (turnover matches calorie intake), or increasing muscle weight (turnover is less than intake). But the benefit here is that when tissue cycling rates are high, even if you're losing weight or remaining weight stable, the body is being remodeled in a positive and functional way. Again, the key is a high calorie intake.
The next important nutritional issue to address is recovery nutrition. Here I'll address how the provision of liquid nutrients in and around the workout can lead to positive changes in the catabolic and anabolic events associated with a bout of resistance exercise. In addition, I'll make specific recommendations about what to take during and around the workout to maximize recovery and the adaptation to the exercise.
The provision of liquid nutrients during and after exercise is important for several reasons. First, an anabolic environment is created, as the exercise and insulin signals are both stimulating cellular activity. Second, such nutrition can shift the net protein status in a positive direction so that muscle protein is being built in and around the workout. Third, muscle recovery is superior due to replenishment of muscle substrates. And fourth, nutrients are rapidly delivered for energy provision when it's most needed.
Below I'll list the ideal beverage composition for both workout and post-workout drinks. After, I'll discuss the literature that supports these recommendations.
Sip immediately before and during exercise:
Carbohydrates (0.4 to 0.8g/kg) – The carbohydrate content of your drink should contain high GI carbohydrates that are easily digested. I recommend a 50/50 blend of glucose and maltodextrin.
Protein (0.2 to 0.4g.kg) – The protein content of your drink should contain easily digested and assimilated proteins like hydrolyzed whey.
Amino Acids (3-5g of each) – The BCAA (Branched Chain Amino Acids) may be important as they're the main amino acids oxidized during exercise. The provision of BCAA during exercise decreases net cellular protein breakdown. In addition, glutamine may spare muscle glutamine concentrations and maintain immune homeostasis during training and recovery.
Creatine (3-5g) – Creatine intake increases work capabilities during exercise, increases recovery of ATP-PC homeostasis, and may increase muscle mass directly/indirectly.
Water (2 L) – The amount of water you consume with such a beverage is crucial since digestion will suffer if you have a beverage that's too concentrated. A solution of 4 to 8% is ideal for proper digestion and hydration during exercise. Any more concentrated and many of those nutrients will be completely wasted. To calculate concentration, remember 10g of total powder in 1L is a 1% solution while 100g of total powder in 1L is a 10% solution.
Editor's Note: Based on these recommendations, John formulated Biotest Surge as the perfect pre- and post-workout drink. (Biotest did not include creatine, however, because some people just don't want it or respond to it. Adding creatine would have also driven up the price, but you can certainly add creatine to your Surge drink if you like.)
Repeat the above beverage but add 500mg of vitamin C and 400IU of vitamin E.
Here's a sample calculation of what a 220lb (100kg) person would need:
40g-80g of carbohydrate (50%glucose-50%maltodextrin)
20g-40g of hydrolyzed protein
3-5g each of creatine, glutamine, BCAA
2L water (80g CHO + 40g PRO + 5g Creatine +5g Glutamine +5g BCAA = 135g of nutrients. In 1L of water this would be a 13.5% solution and too concentrated. In 2L of water this is about 6.75% and the concentration is just right).
40g-80g of carbohydrate (50%glucose-50%maltodextrin)
20g-40g of hydrolyzed protein
3-5g creatine each of glutamine, BCAA
1L - 2L water
500mg vitamin C, 400IU vitamin E
Support for these recommendations
Pre and Mid-Workout Benefits
The benefits of such a beverage during exercise include:
Rapid provision of fuel – Supplementation can provide fuel when it's needed most. Liquid, easily digestible nutrients can be digested, absorbed and delivered in a matter of minutes while whole food meals can take hours to reach the muscle.
Maintenance of blood glucose – Blood glucose can decrease during exercise, leading to local muscular as well as central fatigue. Supplementation can maintain blood glucose concentrations and delay fatigue.
Maintenance of muscle glycogen – As shown earlier, six sets of leg extensions can deplete thigh glycogen by over 40%. Supplementation with liquid carbohydrate during repeated sets of leg extensions can help prevent such a large decrease in muscle glycogen. Compared with the normal 40% decline in muscle glycogen, subjects supplemented with carbohydrate only experienced a 20% reduction of muscle glycogen.
Increased muscle blood flow – While some theorize that the digestion of this drink will draw blood away from the muscle and toward the gastrointestinal tract, this couldn't be further from the truth. Since the recommended drink is so easily digested and the stimulus to send blood to the muscle is so strong, blood flow to the muscle will actually increase with such a drink.
At rest, blood flow to the muscle is quite low. However, during exercise muscle blood flow increases by almost 150%. When a carbohydrate and amino acid drink is taken pre/during the workout, the blood flow during the workout increases by about 350%. This is a very powerful effect since there's significantly more blood going to the muscle and this blood is packed with anabolic nutrients!
Increased insulin concentrations – By increasing insulin concentrations and delivering more of this insulin to the muscle, the extra glucose, amino acids, and creatine that are in the blood will be more readily taken up into the muscle. Studies have shown that the more insulin available in the blood, the more prominent the tissue building effect. The highest insulin response noted (over 1000% increase) was induced by a carbohydrate, protein, and amino acid beverage with the same proportions of nutrients as recommended above.
More positive protein balance (see "positive protein status" below)
Rapid fuel provision for recovery needs (same as above)
Decreased post-exercise cortisol concentrations – After exercise, cortisol concentrations can increase to concentrations 80% higher than resting values. The provision of a carbohydrate supplement can lower the cortisol response to exercise by about half. This means that post exercise cortisol concentrations with supplementation will only be about 40% higher when compared to resting concentrations.
Increased insulin concentrations – By increasing insulin concentrations, the extra glucose, amino acids, and creatine in the blood will be more readily taken up into the muscle.
Rapid glycogen replenishment – After exercise, if nutrients aren't provided, glycogen replenishment won't occur. In one study, a resistance exercise protocol depleted muscle glycogen by 33%. If no meal was consumed and muscle glycogen was measured four hours later, muscle glycogen remained depleted. If a 230-calorie beverage was consumed (either carbohydrate alone, or a macronutrient blend) immediately after exercise, glycogen was fully restored in the four hours.
Stimulation of protein synthetic pathway – Below, I've listed values for protein synthesis under different treatment conditions. Each percent increase is relative to fasting baseline values.
Insulin Treatment – 50% higher
Amino Acid Infusion – 150% higher
24 Hours Post-Exercise – 100% higher
Amino Acids Immediately Post-Exercise – 200% higher
Amino Acids and Carbohydrate Immediately Post-Exercise – 350% higher
Amino Acids and Carbohydrate Given Immediately Pre-Exercise – 400% higher
It should be obvious that pre- and post-workout drinks dramatically stimulate protein synthesis.
Positive protein status – When fasted, during exercise and immediately post exercise, protein status is negative (more protein is being lost than is being retained). With feeding, protein status increases so that more protein is retained than lost. If liquid nutrients are given after exercise, the protein status becomes positive very quickly with the highest increase in the group that gets carbohydrate and amino acids immediately before exercise.
In all post-exercise situations where nutrients are provided, protein breakdown is accelerated (as we'd expect and as I recommend), but the increases in protein synthesis outweigh the increases in breakdown and lead to large increases in protein retention.
Anabolic hormone changes seen with exercise are relatively unaffected – Testosterone decreases slightly after exercise when any type of food is consumed but the change is small and won't impact muscle mass. In addition, while GH declines with carbohydrate intake at rest, after exercise the signal to release GH is very strong and is unaffected by nutritional supplementation. Therefore a drink given post exercise won't diminish any small effects that the anabolic hormones may have on the body.
Prevention of free radical damage – The vitamin C and E recommendations are in place to help prevent excess free radical induced cellular damage. The exercise itself as well as the acute phase response leads to free radical production. The antioxidants may save the cell from free radical damage.
Rapid ATP/PC recovery – Intense resistance exercise leads to the loss of substrate from the ATP/PC system. Creatine supplementation can help the body more rapidly resynthesize these substrates.
At this point I must be completely frank by acknowledging potential critics. Some may argue that the data supporting these recommendations are incomplete. They may argue that there are no studies showing that using a Biotest Surge type of beverage will improve athletic performance or increase muscle mass. They will argue that there are no proven benefits to such a blend.
In response I must concede that they're correct, at least partially. There are no such long-term studies at the present time. However, in our laboratory and others, research is currently being conducted to address these concerns. But, as we all know, research takes time. So what does one do until the debate is settled?
You could certainly stay on the fence and wait until the data are in. However, in the mean time, I believe that the evidence and real world feedback weighs in strongly that such a beverage will offer significant benefits. And as Arnold Schwarzenegger said in the movie Pumping Iron, "All these things are available to me. And if they are available to me, I might as well use them."
I'll go one step further in saying that you should use them.