My name is Nick and I am currently doing my PhD in physiology with an emphasis in muscle physiology. Welcome to my exercise science blog. Unlike a lot of fitness blogs out there, this one is unique because it is backed by true science. You will find only articles that have been peer reviewed and published in top tier science journals on this blog. For the fast easy read, just read the bold type. If you have any questions do not hesitate to ask me. I am at your disposition for any advice in exercise or just basic physiology. This is not a progress blog to benefit myself but rather to share some of my knowledge and expertise with you that I have gained over my years dedicating my career to exercise science. If I do not know the answer, I will do my best to search through the journals to find it for you. Although I am in biomedical research, I am not a licensed medical professional so please consult a physician before entering any exercise or nutrition program.
The following was presented by Eric Rawson at the 2013 ACSM Conference. It is my pleasure to share it with you.
1.) Creatine monohydrate
Doses: 0.3 g/kg/day for 5 days or 0.03 g/kg/day for 30 days is sufficient to increase the concentration of creatine by 20-25%.
Washout period: 6 weeks is usually recommended
Performance factor: Increase performance of high intensity exercise of durations less than 30 seconds
Safety profile: Excellent
Doses: 3-6g for 4-8 weeks can elicit 40-50% increases. Acts as a buffer
Washout period: 10-15 weeks
Performance factor: Good for H.I.I.T. or sprinting. High intensity exercise (1-6min duration). Overall 2.58% increase in performance
Safety profile: Safe but may cause a niacin flush (paresthesia)
3.) Sodium Bicarbonate (NaHCO3)
Doses: 300mg/kg taken 1-3 hours pre-exercise can act as an extracellular buffer
Washout period: None. Some suggest as a chronic dietary supplement.
Performance factor: 1-2% increase in body mass. Increase in high intensity exercise (1-5min). Shown previously to take 0.8s off of a 1 min race.
Dose: 0.4 g/kg/hour of exercise (Milk is the best bang for your buck) 1.6-1.7 g/kg/day.
I think it also important to not neglect your carbohydrates. In exercises lasting 30 seconds to 1 minute, a lot of people think that most of the energy is coming from creatine. In actuality, 10% is coming from creatine whereas 47-60% is coming from carbohydrate stores. 1.2 g/kg/hour of carbohydrates post-exercise is sufficient for muscle glycogen resynthesis.
Are you a girl who regularly skips breakfast? Read on because this well-controlled study is for you.
Introduction: Breakfast skipping is strongly associated with a greater chance of weight gain. Furthermore, this trend is also linked to poorer food choices. Higher protein meals are becoming more popular as a way to improve satiety and appetite control. The purpose of this study was to examine if it is better to skip breakfast or eat one higher in protein in regards to appetite control throughout the remainder of the day.
Methods: Twenty overweight or obese girls between the age of 15-20 who normally skip breakfast were recruited for this study. They were tracked for 7 consecutive days and randomized to one of 3 groups: breakfast skipping (BS), a normal cereal meal for breakfast (NP), or a high-protein breakfast (HP) consisting of beef and eggs for breakfast. Breakfast and lunch were controlled but the rest of the day they were free to eat as much as they wanted.
NP & HP led to a 60% reduction in daily hunger.
HP lead to a greater increase in total fullness.
NP & HP led to a 30% reduction in daily desire to eat.
HP breakfast but not the others suppressed an important hunger stimulating hormone (ghrelin) by 20%.
HP breakfast but not the others increased an important satiety-stimulating hormone (PYY) by 250%.
BS & NP led to greater evening snacking than HP.
Discussion/Conclusion: A small breakfast of merely 350kcal led to reductions in perceived hunger, the desire to eat, and prospective food consumption. In addition, it also increased fullness. What is even more interesting is that the high-protein breakfast group had additional benefits of a reduction in the hunger-stimulating hormone ghrelin, increases in PYY (a hormone that makes you feel fuller), and decreases in evening snacking, particularly of high-fat foods. The authors note that a limitation of this study was that the breakfast skipping group and the high-protein group had similar total amounts of calories consumed during the day. Although this study looked at 1-week of food consumption, it is not certain if eating a high-protein meal for longer periods of time (a year or more) would prevent weight gain.
My input: The most obvious inferences that the authors draw come from the simple fact that the breakfast skipping group is fasted. Of course, their perceived hunger/fulness, desire to eat, and prospective food consumption will be higher in the morning because they just woke up. I think the most powerful part of the study came from the blood draws and the actual measurable physiological significance that a high-protein breakfast did decrease a hormone responsible for making you want to eat and increase a hormone that tells your brain that you are full.That is what truly stands out as powerful rather than all the other results based solely on questionnaires. For that reason, I’d suggest trying out the high-protein diet over your standard cereal-based breakfast and seeing how it works with your own feelings of satiety throughout the day.
Maximize your muscle protein synthesis after weight training, bros. I’ll highlight for you a recent review, which the scientist nerds can read entirely for free here, from Dr. Stuart M. Phillips. I encourage you to take the time to read this one.
Introuction: When scientists talk about muscle protein synthesis they are referring to accruing muscle proteins in an overall net positive balance. That is to say, taking the most basic form of proteins, amino acids, and eventually creating structural muscle (aka hypertrophy). Normally, this is done by adding to already existing contractile machinery of the muscle cells. Researchers suggest that muscle protein synthesis (MPS for now on) is controlled by certain factors including dose, food source, and timing. Let’s see what Dr. Phillips has to say about each of these areas.
"The anabolic window" -Timing
It’s like the holy grail of muscle growth for bros. ”You can’t miss the window or you ruined the entire workout.” Well, that’s a bit exaggerated. Phillips states that, "It is now unequivocal that immediate post-exercise amino acid provision is an effective nutrition based strategy to enhance MPS above rates observed with exercise alone.”Early post-exercise ingestion of amino acids or protein comes from studies that showed that exercise induced increases in rates of MPS are greatest right after exercise; approximately 100-150% above basal rates. However, it may not be that big of a deal if you miss this window. If you look at the figure below, the increase in MPS is in fact greater after exercise but can remain elevated for up to 48 hours. Phillips suggests that consuming protein during these later times as well can be just as beneficial as ingesting protein directly after exercise.
More importantly, Philips discusses the importance of actual exercise intensity and how it relates to muscle failure. This is in lines with a study I touched upon in the past. Looking at yet again another figure below, you can see that groups that take resistance exercise to failure, regardless if they’re using heavy load and low volume, or a light load and high volume had an enhanced amino acid sensitivity to muscle protein synthesis. Let me say that again, IRREGARDLESS OF HOW MUCH WEIGHT YOU USE, as long as you are taking the muscle to failure, you will increase your rates of muscle protein synthesis more than loads not till failure.
Let it be noted that whey, egg albumin, soy, casein, and beef have all been shown scientifically to be able to stimulate MPS. However, the Philips group has shown in the past that whey and milk can increase MPS greater than soy products following resistance exercise (this could be due to differences in amino acid profiles and/or digestion kinetics). Why is whey fast-digesting and casein slow-digesting? Every one knows that or will tell you that but do they even have an explanation why? Phillips drops a knowledge bomb with one sentence, “Whey protein is acid soluble and is associated with a very rapid, large, but transient increase in postprandial amino acid availability, while casein coagulates and precipitates when exposed to stomach acid and the resultant dairy curd is slowly released from the stomach resulting in a much more moderate but sustained rise in plasma amino acids.” I love knowledge bombs.
It is still accepted that in young healthy individuals, approximately 20-25g (which corresponds to approximately 8-10g of essential amino acids) of a rapid digesting protein source (whey or milk) can help maximize stimulation of MPS after resistance exercise.
"Yo, you gotta take your casein before bed so you stay anabolic. Steady flow of amino acids while I sleep." How many times have you heard that? How many people have showed you a study validating it? Finally, one exists.
Introduction: It is hypothesized that ingesting protein before sleep could be beneficial to increase plasma amino acid availability, stimulate skeletal muscle protein synthesis and increase whole-body protein balance during sleep. Thus, this group took 16 recreationally active young men and after a single bout of resistance training gave them either casein protein or a placebo before bed. This is the first study to look at the effect of ingesting casein protein immediately before sleep and subsequently seeing how it effects protein synthesis and protein balance overnight.
Methods: All subjects received a standard meal the evening before the test and a standardized diet throughout the experimental day. Tracers were implemented in this study which allows for measurements of certain molecule in the blood. A tracer is a molecular that contains radioactive isotopes that can be measured by machines to see the overall flux of the molecule throughout the body. In this study, the researchers traced radioactive amino acids (it’s safe because they are stable isotopes, trust me)throughout the night following the exercise protocol. The protocol consisted of leg extensions and leg press and was performed three hours before bed.
Results: After ingestion of protein before sleep, the total essential amino acid concentrations in the plasma increased rapidly and stayed higher throughout the night as compared to the placebo group. For the tracer, the amount of protein available from the plasma-derived amino acids was 50% higher in the protein ingestion group at time 7.5hrs after sleep compared to the placebo. Finally, whole-body protein synthesis rates were higher in the protein group versus the placebo group.
Discussion: It is evident that the casein protein was in fact digested and absorbed normally throughout the night because the tracer used in this case came directly from the casein protein shake. Not only did they observe and increase in whole-body protein synthesis with the blood plasma samples, but the group also showed an increase in synthetic rate by taking muscle biopsies as well. Of course this could not be confirmed throughout the night but only before bed otherwise the person would not be able to sleep when the biopsy was being performed. Also, it is important to keep in mind that this is an acute (one-time) bout of resistance training and not chronic (long-term).
Casein protein at bedtime is effectively digested and absorbed which would lead to an increase in available amino acids from blood plasma overnight
Casein protein at bedtime stimulates muscle protein synthesis rates which would increase overnight protein balance.
My input: This study highlights the practicality and necessity of using tracers. Without labeling the amino acid in the casein drink, it would be difficult to tell whether or not the amino acids in the plasma are coming from inside the body (endogenous) or what was ingested (exogenous). The authors clearly show in the figures that the rise in the amino acids come from the isotope labelled casein source that they provided. Now for the first time, you can all finally tell your friends it is a good idea to supplement with casein before bed because science suggested it.
1kg (2.2lbs) of skeletal muscle contains approximately 650g of intracellular water. Representing normally around 40% of body weight, skeletal muscle in the whole body contains 80 grams of amino acids in the intracellular pool. The amino acids glutamine, glutamic acid, and alanine contribute approximately 80% to this pool.
Whey protein or leucine post-workout to increase muscle protein synthesis (MPS)? The Phillips group just published an article trying to answer this question.
Introduction: You all are probably aware that ingesting amino acids stimulates an increase in muscle protein synthesis even without resistance training. Leucine has been toted to best stimulate MPS by activating components of a signalling cascade known as mTOR. There is still controversy though as to whether or not leucine can enhance MPS following leucine infusion or by simply adding more of it to a post-workout protein drink. This group previously reported the the optimal dose of protein post-workout to stimulate MPS was 20g and that anything below this is not sufficient and anything above this number (40g) does not increase MPS further. Therefore, the aim of this study was to see if taking a “sub-optimal” dose of whey (6.25g with approximately 0.75g of leucine) protein and supplementing it with leucine or a mixture of essential amino acids without leucine would have an effect on MPS at rest and after acute resistance training. This will be compared to a dose of whey (25g with approximately 3.0g of leucine) which is sufficient to induce maximal stimulation of MPS after resistance exercise.
Methods: Twenty-four adult males were randomized to one of three groups that either ingested a whey protein drink, a leucine drink, or an essential amino acid drink. Prior to ingestion, the volunteers completed an acute bout of unilateral resistance exercise (knee extensions). Muscle biopsies were taken at the time of ingestion and at time points 1 hour, 3 hours, and 5 hours post-exercise.
Results: After whey protein ingestion, blood leucine, branch-chain amino acids, essential amino acids, and total amino acids were all highest as compared to the groups that ingested leucine or EAA (without leucine). Blood leucine was only higher initially after ingesting the leucine drink but stayed elevated longer by ingesting whey. Rates of MPS remained increased for 3-5 hours at exercise recovery above those volunteers who did not ingest anything, versus the groups who ingested leucine or the EAA drink.
Discussion: A dose of whey protein that has been previously shown to be less than maximally effective to stimulate MPS after resistance exercise, when supplemented with leucine, resulted in an early (1-3 hour post-exercise recovery) increase in rates of MPS equal to that of ingesting 25g of whey. Also, the same was found by supplementing a low dose of whey with essential amino acids void of leucine. However, MPS was sustained longer (3-5 hours post-exercise) only with the group that ingested whey protein. These differences occurred despite the fact that blood amino acid levels returned to baseline after 3-5 hours but MPS still continued. Therefore, the authors state that peak activation of MPS does not appear to be driven by increasing leucine in the blood and that amino acid transport across the sarcolemma (plasma membrance of the muscle cell) and intracellular amino acid availability may be important in the regulation of MPS.
Conclusion: Leucine stimulates MPS post-exercise equal to that of whey protein, despite only containing 45% of the total EAA content of the whey. However, similar increases in MPS were observed in the EAA ingestion group that did not contain leucine. Thus, the authors speculate that in young healthy individuals, the leucine content provided by approximately 6.25g (approximately 0.75g of leucine) of whey protein seems adequate to maximally stimulate MPS if sufficient amounts if the other EAA are provided (approximately 8.5g EAA). Also, the whey protein ingestion group was the only group that sustained MPS 3-5 hours post-exercise.
My input/practicality: What if I were to tell you I can make a 1lb bag of whey protein last me 3 months? Well I can, and I do, and I’ve been doing it for years. I only use a half scoop of whey protein post-exercise. Never a full scoop. Never a “heaping” scoop. Why do you even think they use the word heaping? It’s all about the dolla dolla bill y’all. This study shows that only 6.25g of whey is necessary to maximally stimulate protein synthesis as long as it contains approximately 750mg of leucine and 8.5g of the other 8 essential amino acids (which are histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine). Make sure you check on the labels of your favorite whey protein because it usually lists the amount of leucine and the other essential amino acids on it. One scoop of whey is usually on average around 20g of protein so if you use a half scoop like me it is around 10g (still a little over from what this study suggests). Supplement companies are going to hate this study (like they read them anyways) as well as me for posting this but you’ll love it/me for saving you money.
This post stems from a question about whether or not there is a significant hormonal rise during leg training that is enough to elicit increased size in other muscles of the body.
With all things aside, the answer to this question is, yes.There are significant increases in testosterone in exercises such as Olympic lifts, deadlifts, and jump squats (lifts that use a relatively large amount of muscle mass).It’s even suggested that one should perform exercise with large muscles first before smaller muscles with the thought of the surge in testosterone from the large muscle groups increasing the hypertrophy effect on the smaller muscle groups.Below is a table from a review that shows various methods of training and whether or not they show significant increases in testosterone.
Now for some testosterone physiology (and I’ll keep this short & simple, I promise).Testosterone works by binding to intracellular androgen receptors that translocate to the nucleus of the cell eliciting a complex which transcribes specific genes.When you perform large muscle mass lifts, your body will subsequently release testosterone which will mainly be bound to sex-hormone binding globulin (44-66% of free testosterone).The amount of testosterone that is biologically active is in a free form.Unfortunately, (for those wanting to put on muscle), only 0.2-2% of testosterone is in the free form.Specifically in the muscle, testosterone increases the amount of androgen receptors in the muscle, stimulates protein synthesis, inhibits protein breakdown, promotes satellite cell (stem cells of muscle) replication and activation, and increases IGF-1 (insulin-like growth factor-1).
With this said and the plethora of articles that support it, I would like to change your mind on this entire idea of large increases in hormones being the main reason for increases in hypertrophy. Where is the fun in believing one method and never doing any inquiry of your own?My interest from this came a few years ago when I read some studies that castrated mice still possess the ability to increase their muscle size.I now want to direct you to some recent studies that can argue the point of an intrinsic process for muscle hypertrophy not due to increases in growth hormone or testosterone.
The two intrinsic local processes in the muscle are sarcomerogenesis and remodeling which both prime the muscle for protein accretion and subsequently, hypertrophy.These are both mechanical steps, if you will, in allowing the muscle cell to become plastic and respond to the stress placed on it by resistance training.Think of it as an entire system of sensors beginning at the membrane of the cell in which these sensors respond by releasing complex signals into an array of converging pathways with one end goal, growth.The following diagram is the proposed pathway working through the protein p70s6k (which scientists are now saying is a better predictor of hypertrophy because this protein increases significantly after training and outlasts the period of growth hormone release):
To conclude, sure there is a large rise in hormones following training that includes large muscle mass.However, studies are starting to emerge that show that testosterone, GH, and IGF-1 may not be the entire mechanism necessary to induce hypertrophy.Hope this answered your question.
Back to the carbohydrate + protein for post-exercise recovery story. This time, looking at proteins inside of the muscle.
Introduction: Studies suggest that adding protein to a carbohydrate recovery drink increases muscle protein synthesis (MPS). However, no studies have attempted to discover specific protein fractions that contribute to MPS in the muscle and the mitochondria. Hence, the specific aim of this study was to do just this experiment following a bout of cycling.
Results: Ingestion of CHO + PRO increased the levels of the amino acids phenylalanine, leucine and threonine by 37, 130 and 58% which peaked 1 hour after exercise whereas in the CHO only group they peaked 30 min after. mTOR phosphorylation (a marker of protein synthesis) was the same post-exercise; however, it increased four hours later with CHO + PRO whereas it decreased at this time with ingestion of just CHO. Mitochondrial protein synthesis rates were similar for both groups. As shown in numerous other studies, myofibrillar protein rates (the contractile properties of the muscle) were approximately 35% higher with CHO + PRO than just CHO alone.
Conclusion: "We have shown that when protein is co-ingested with carbohydrates after cycling exercise myofibrillar, but not mitochondrial, protein synthesis is increased. It is possible that frequent post-endurance exercise protein ingestion may promote muscle hypertrophy over time.”
My input: A lot of the other protein fractions that the researchers looked at failed to show any significance between the two groups. All in all, this is just another study supporting supplementation with a protein post-exercise can create a physiological environment that favors increases in muscle mass.
Breen et al J Physiol. 2011 Aug 15;589(Pt 16):4011-25
Let’s step away from the molecular stuff for now and go back to some practical studies. Are you adding carbohydrates to your protein drinks after resistance training hoping for added growth?
Introduction: We know that muscle protein accretion occurs when muscle protein synthesis (MPS) is greater than muscle protein breakdown (MPB). Hyperinsulinemia, induced by adding carbohydrates to your protein drink, is thought to aid in this protein accretion. So, researchers sought after this to see if it works.
Hypothesis: Insulin (from the ingestion of carbohydrates) would augment protein-stimulated inhibition of MPB after exercise but not at rest.
Methods: 9 young recreationally active males mean age 23 performed unilateral leg extension testing for each leg for 4 sets of 8-12RM. The consumption of a protein (25g of whey) or protein+carb (25g whey + 50g maltodextrin) drink was added during this time.
Results/Conclusion: Addition of carbohydrates to a protein drink does not increase rates of MPS nor does it further inhibit MPB.
My input: It is a low sample size (9 participants) but it still has enough power to contribute to the field. It is imperative to note that this study uses the tested dose of whey protein (25 g) that significantly increases markers of protein synthesis necessary for recovery and growth. Thus, save your extra scoop of whey for the next session because it is simply not needed. Insulin release in this case did not aid to MPS, but it is also important to note that whey protein can digest so rapidly that it will also cause spikes in insulin, enough to the point of increasing MPS without the addition of carbs. This is important for people watching their carbohydrate intake for weight loss purposes because data from this study suggests you will not need to add additional carbs to aid in muscle recovery. In fact, insulin is not entirely necessary for skeletal muscle to uptake the glucose for replenishing lost glycogen stores. More studies will indeed follow in this area but for now, no further insulin is needed.
Introduction: Adaptations from exercise in skeletal muscle is thought to be induced by the creation of reactive oxygen species (ROS). One such process in the muscle is via an increase in mitochondrial content and density which are the main adapatations that occur in muscle after endurance exercise training. Genes and transcription factors that govern these adaptations include PGC-1alpha, NRF-1&2, Tfam, cytochrome C and it’s enzyme (COX IV) (protein that controls oxidative phosphorylation), and citrate synthase. Antioxidant supplementation (vitamins E, C, and coenzyme-Q10) blocks ROS. Thus, they may block the main cell signaling processes invovled in skeletal muscle adaptations to exercise training.
Results: Antioxidant supplementation in both exercise and sedentary groups reduced the expression of:
PGC-1alpha mRNA & protein
COX IV protein
citrate synthase activity
There was no significant interaction effects between exercise and antioxidants.
Conclusion: Prolonged antioxidant supplementation could potentially impair the endogenous metabolic and redox status (ROS creation) of skeletal muscle in sedentary people and prevent some of the beneficial adaptations to exercise training.
My input: One of the major setbacks of this study is that it was performed in rats and not humans. Other than that, the study design is very well done. As the authors noted, this is long-term antioxidant supplementation of 14 weeks which is necessary for Vitamin E (the antioxidant that they used) to even enter skeletal muscle. In fact, they cite another study that shows that the other popular antioxidant supplement, Vitamin C, is poorly taken up in skeletal muscle. Therefore, it may be to your advantage to not include supplementation with Vitamin E due to its diminishing effects on mitochondrial markers necessary for adaptation to endurance training. Escpecially if you are a beginniner to endurance training.