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.
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.
Weight training and some form of aerobic in the same session. Does it hurt or help?
Introduction: Exercise scientists use the term concurrent exercise when referring to resistance training and aerobic exercise being performed in the same session. These two modes of exercise are different in regards to skeletal muscle profiles and therefore may not be compatible with one another on the cellular level. This is noted as an “interference effect” between the different signals occurring in the muscle. The purpose of this study was to see the effects of a short bout of aerobic exercise on the molecular responses that are supposed to control exercise-specific muscle adaptations to resistance exercise.
Methods: The subjects (9 men) underwent one-legged aerobic exercise in the morning followed by four sets of resistance exercise six hours later. One leg received both aerobic and resistance exercise while the other volunteer’s leg served as a control and only received resistance exercise. Standardized meals were given the day before and the day of to each person and muscle biopsies were taken.
Results: The leg that underwent both aerobic and resistance exercise decreased in muscle glycogen more than the leg that just did resistance (makes sense). A well-known marker of mitochondrial biogenesis was higher in the leg that underwent both training modes. Another marker or muscle size regulation (myostatin) was significantly lower in both the resistance trained leg and in the leg that underwent both modes. Finally, a marker of protein synthesis was higher in the leg that underwent aerobic plus resistance training than the other leg.
Discussion/conclusion: From this study, the authors conclude that concurrent exercise may in fact enhance the skeletal muscle anabolic environment although it is important to note that these differences between legs were modest. An interesting finding is that the well-known marker of mitochondrial biogenesis which is usually increased from endurance training also increased from the resistance trained leg as well. Myostatin inhibits muscle hypertrophy and the finding that both legs decreased myostatin levels shows that both training modes could be effective at increasing muscle mass (although both legs did resistance and this very well may be the main reason for that). In conclusion, the authors state that both exercise types can be scheduled on the same day without compromising important molecular signals in the muscle.
My input: I’ve written about this previously on my blog. This study has similar results to the other in that they conclude resistance training after aerobic training may in fact enhance muscle machinery and subsequently help with performance. Although, the two studies are truly hard to compare due to the fact that this current one waited 7 hours later to do the resistance training, while the previous one I wrote about hit the weights immediately after. A great strength of this study was using one leg for aerobic and resistance exercise and using the person’s other leg as the control that just received resistance exercise. As far as a doing weights after cardio on the same day in the gym, there seems to be no immediate inference effect but this can not yet be extrapolated to more long-term sessions.
"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.
I read three articles this week solely for the purpose of posting on here but it turned out I didn’t like any of them. So I apologize for not giving you all a new article. Instead, I suggest checking out this week’s ACSM sports medicine brief written by my doctoral adviser on how much exercise is necessary to improve insulin resistance.
The title says it all. Who is better able to recover following resistance training? The results may surprise you (or even motivate you).
Introduction: Researchers sought out to see whether men or women have higher rates of protein synthesis during the early (1-5) and late (24-48) hour recovery periods. In addition to the resistance training, they also gave a dose of whey protein (25g) that is expected to induce maximal muscle protein synthesis. A secondary aim of this study was to see if the large amount of testosterone released by men post-exercise (10 to 15 times higher in men than women) would have an additive effect on muscle protein synthesis that women would not be able to obtain.
Methods: Eight men and eight women who were participating in regular physical activity took part in this study. The bout of exercise was an intense bout with 5 sets of 10 reps at 90% of a persons 10 rep maximum on the leg press as well as 3 sets of 12 reps of leg extensions/leg curls supersets. Upon finishing this workout, subjects were given 25g of whey protein.
Results: Starting rates of protein synthesis were similar between men and women. After exercise, protein synthesis increased in men and women at 1-3 hours and remained elevated at 26-28 hours after with no difference between the sexes.Testosterone was approximately 45 times greater in men than women fifteen minutes after exercise but did not have an effect on muscle protein synthesis more than that of women.
Discussion/Conclusion: This study shows that there are similar rates of muscle protein synthesis as well as anabolic cellular signaling events between men and women following resistance training plus a 25g dose of whey protein in the earl and late phases of post-exercise recovery. Even though men had a far greater increase in testosterone than women post-exercise, it was not enough to increase protein synthesis more than women. Therefore, the anabolic effect of resistance exercise clearly is working through some other mechanism other than spikes in testosterone levels.
My input: So, men do not have it easier when it comes to weight training anabolic responses. Both sexes are primed equally for muscle recovery. The fact that they looked at testosterone comparisons really added to the quality of this study. It is important to note that the authors are referring to muscle protein synthesis during a recovery phase and not muscle protein synthesis in a long-term muscle building sense. However, recovery is the first step to adding muscle.
Have a 5K coming up or a race in a track meet? Would you like to improve your time in the event (wow, it sounds like I’m trying to sell something)? Well, a group from Denmark just published a paper with an interesting endurance training method to help you reach your new time goal. This one is for the runners and I assure you I’m not selling anything but exercise.
Introduction: It is known that people who are already trained need to intensify their training protocols to continue to improve. Training at maximal or near maximal intensities creates the muscular adaptations necessary for these improvements. A popular method to do this is introducing 30 second sprint intervals into your training coupled with a short recovery period. Normally, this is repeated 4-5 times. However, it is uncertain whether training using just 10 second near maximal sprints has the same effect as the 30 second intervals. In addition, it is unclear whether training at this high of an intensity can affect the health profile of people who are previously trained. Therefore, the 10-20-30 training concept is introduced and tested to see whether or not it can lead to endurance performance, increases in cardiovascular fitness, as well as health.
Methods: Eighteen moderately trained individuals (12 males and 6 females) were divided into 2 groups, the 10-20-30 group or a control group. For a period of 7-weeks, the 10-20-30 group trained with this method whereas the control group continued with their normal weekly training sessions (2-4 times per week, 27km and 137min total). The 10-20-30 training concept consists of 3-4 x 5 min running interspersed with 2 min of rest. During the 5 min running period, a person would run 1 min of an interval divided into 30, 20, and 10 seconds at an intensity related to <30%, <60%, and >90-100% of maximal intensity. They performed this 3 times per week with a volume of 14 km per week. To test differences in the training methods, the groups performed a 1500m race, a 5-K run, and a running test to exhaustion.
Results (after 7 weeks):
The 10-20-30 group improved performance by 6% in the 1500m and 4% in the 5-K run with no difference in the control group.
The 10-20-30 group increased their VO2max (maximal oxygen uptake) by 4% with no changes in the control group.
The 10-20-30 group lowered their total cholesterol and LDL cholesterol with no changes in the control group.
The 10-20-30 group’s systolic blood pressure was lower with no changes in the control group.
Discussion: After a 7-week period, the 10-20-30 training method, lead to an increase in VO2max of 4% and decreased times on the 1500m by 21 seconds and on the 5-K by 48 seconds. In regards to health, this training concept also decreased LDL cholesterol as well as resting systolic blood pressure. This all occurred even though the volume of training reduced by 54%. One explanation for this by the authors is that high cardiac stress (the max effort 10 second sprints) coupled with a reduction in training volume is sufficient enough to increase VO2max because the group that did the 10-20-30 spent approximately 40% of training time spent above 90% of maximal heart rate whereas the control group spent 0% of training at this level. For health parameters, the authors also state that the 5 mmHg decrease in systolic blood pressure is of clinically significant because a decrease such as this can reduce the risk of cardiovascular death by 10-15%.
Practicality: If you were wondering approximate running speeds in case you want to try this out on the treadmill, the 10 second intervals were at speeds >20 km/h, the 20 second intervals were between 10-14 km/h, and the 30 second intervals were <10 km/h. For those still having trouble understanding the 10-20-30 principle I will give an example: You would run a warm-up of 5 min at a very low intensity, following this you would begin the 5 minutes interval which is divided into 10-20-30 seconds for each minute. You run <10 km/h for 30 seconds then right away increase the speed to 10-14 km/h for 20 seconds then again immediately increase the speed to >20 km/h (or as fast as you can run for 10 seconds). After repeating this another 4 (to make 5 minutes) times you would then have a recovery period of 2 min at a low intensity before repeating the 5 minute intervals 2 or 3 more times. For those who have tight time schedules, this is practical because all of these improvements with this technique can be accomplished in just 30 minutes. The authors also state that 10-20-30 is also applicable for anyone who is sedentary up to elite running levels.
Taking ice baths post-exercise seems to be the most popular method of reducing delayed onset muscle soreness for novice and elite athletes. This method, known scientifically as cryotherapy, is growing to be more popular than traditional ones such as massage, stretching, or taking non-steroidal anti-inflammatory drugs (NSAIDs). The most popular forms of cryotherapy are cycling 1 min in ice water (5 degrees Celsius) followed by 1 minute out for a total of three times or a longer duration of 15 minutes at 15 degrees Celsius. Now that you have the background, I’ve went out and found an enormous extensive review on the subject to make clear whether or not this technique is useful or useless at combating muscle soreness and aiding recovery.
The scientific claims: You know that you treat sprains, strains, or any swelling in the body with ice. The mechanisms for why cryotherapy works are similar; reduce pain, swelling, and inflammation. There is also vasoconstriction (decreasing the diameter of the blood vessel) which stimulates blood flow and nutrient and waste transfer as well as decrease in nerve transmission speed, which could alter the threshold of pain receptors.
The studies used: The review included 17 small trials (published from 1998-2009) of 366 participants. No restrictions were placed on age (16-29), gender female, or type of level of exercise. Also, no restrictions were placed on duration or frequency of immersions or depth of immersion. The studies were all of small sample size (20 participants or less) except for one that used 54.
The exercises used: All exercise used were designed to produce delayed onset muscle soreness (DOMS) under laboratory controlled conditions. Repetitions for resistance exercise ranged from 50-100 of eccentric or alternative concentric and eccentric contractions. The other studies used running or cycling in single bout efforts (for the bike) or steady state efforts. Few actually included team sport exercise (basketball and soccer).
The cryotherapy used: The most common for the studies was 10-15 degrees Celsius with an average immersion of 12.6 minutes. This was employed in almost all of the studies immediately after exercise. The different methods of cold-water immersion were compared to nothing/rest (the most common), cold-water immersion vs. contrast immersion (switching between hot and cold), cold-water immersion vs. warm water, and cold-water immersion vs. active recovery.
Enough with the technicalities. Let’s go to the results.
Cold-water immersion vs. nothing: In terms of muscle soreness, there is no significant difference immediately between the two conditions but at 24, 49, 72, 96 hours later the cold-immersion group reported a significantly lower amount of muscle soreness than the group that just rested. This effect seems to be more prevalent after running based exercises than resistance exercises but the authors not that due to the various types of exercises that were performed between all the studies, plus the sample sizes being small, it is difficult to find whether or not this is truly significant. There were no significant differences in strength, power, functional performance, swelling, or biomarkers of muscle damage.
Cold-water immersion vs. contrast immersion: In terms of muscle soreness, there was no significant differences between the groups. Also, there was no significant differences in strength, power, functional performance (time to fatigue), swelling, range of movement, or biomarkers of muscle damage.
Cold-water immersion vs. warm-water immersion: There was significant lower levels of muscle soreness reported only for the cold-water immersion group at time-point 96 hours with no differences in strength, power, functional performance, swelling, or biomarkers of muscle damage.
Cold-water immersion vs. active recovery: There are no significant differences in reports of muscle soreness, strength, power, functional performance, swelling, or biomarkers of muscle damage.
Discussion/Conclusions: Cold-water immersion did significantly reduce muscle soreness at time points 24, 48, 72, and 96 hours post-exercise. However, it is important to note that these were all subjective reporting (self-reports) and the authors state it is hard to draw true conclusions from the data due to poor methodological quality. There were high risks of bias due to the fact that blinding was performed poorly as well as concealment of group assignments (only 1 study did this effectively). There were also large differences in the types of exercises used and subjects were a mix between trained and untrained. The effectiveness very well may rely on the specificity of the exercise performed as well as the athletic level of the individual.
My input: Did you know that in the 1920s, cyclists in the Tour de France would smoke during the race because they believed that smoking opened up the blood vessels and oxygen transport machinery of the lungs? Ridiculous, right? I’m not saying ice-baths are as crazy as this, but are they truly beneficial to aid recovery in the muscle? I’m not so sure. From the most basic laws of chemistry, we know that when something is heated up the molecules in it move faster and when something is cooled down the molecules in it slow down. If you are exposing your muscles to cold, all of the molecular processes will slow down. You need enzymes (which function effectively at specific temperatures) and proteins moving post-exercise to begin the repair process and signal inflammation, and if you’ve read my previous posts on muscle hypertrophy, you know inflammation is necessary. It is the same reasoning to avoid NSAIDs in hopes of reducing muscle soreness. For this reason, I’m always heading for the exact opposite after training, a hot shower. The reason I do this is not only to continue normal biochemical processes in the muscle but also to incorporate the activation of what are called heat shock proteins. Heat shock proteins are proteins in the body that respond to stress or elevated temperatures. They function as chaperones for other proteins by aiding them to conform to a certain shape and stabilize proteins that are not shaped properly. Basically, they can clean up the mess inside of the muscle cell and help with repair. This is another reason why I’m not on the ice-bath bandwagon. You might feel that it has helped you before in the past and it possibly could have helped, but I just want to let you know there is no scientific evidence supporting it. The studies are low quality studies. If you truly want a good study on this, take a group of at least 35 people, train their legs or their arms simultaneously with the same protocol and put one limb in the ice and one limb not in the ice or in warm water, take muscle biopsies, and see the differences between the conditions (Anyone want to take this on as a nice Master’s or PhD project? I’ll be glad to give advice for it). To my knowledge this has not been done and this would be the best way to see if cold-immersion truly helps. Although there was some evidence in a decrease in self-reported muscle soreness, I’m still not convinced and higher quality studies are necessary before I’ll be convinced.
You’ve heard the debate before, you know you have. High intensity interval training (HIT) versus continued steady state running. Which is better? A new article has been published showing that when it comes to the two, they may in fact be more similar than we initially thought.
Introduction: When we talk about adaptations to endurance training, we’re talking about muscle mitochondria. These adaptations are thought to be turned on by increases in molecular responses from the onset of contraction (e.g. increases in the AMP/ATP ratio, calcium levels, reactive oxygen species, lactate, reduced glycogen availability, etc). All of these lead to activation of proteins called kinases which phosphorylate targets such as transcription factors or transcriptional coactivators. Okay, I know, too much science. It’s gross for you. Basically, what this means is that these signals increase markers responsible for allowing the mitochondria to adapt to the endurance training and subsequently, you become a better athlete. However, it is uncertain if there is an optimal exercise stimulus to create these adaptations. Therefore, the aim of this study was to see the whether or not the signals of these molecular responses after an acute bout of either HIT or continuous running increase greater for one mode of exercise or the other. The primary hypothesis is that HIT will increase these signals responsible for adaptation to a greater level than that of continuous running.
Methods: The study recruited 10 recreationally active males who underwent both the HIT and the continued running protocol. For those unfamiliar with HIT, the protocol was 3-min running at 90% of one’s maximal oxygen uptake followed by a recovery period of 3-min at 50% maximal oxygen uptake (this was repeated 6 times). The group in the continued running ran the entire time at 70% maximal oxygen uptake. Muscle biopsies were taken pre-exercise, post-exercise, and 3 hours after exercise.
Results: Muscle glycogen decreased by 30% in both groups but there was no difference between HIT and continuous running (CONT). There were increases in all of the molecular markers of mitochondrial content (AMPK, p38MAPK, PGC-1a) in both HIT and CONT but again, no differences between the two modes.
Discussion/Conclusion: This is the first study to demonstrate that both HIT and continuous running induce comparable responses of molecular markers in muscle. The authors state that this could be due to both protocols being relatively intense since there is only a difference of 20% maximal oxygen uptake between the two groups. Another first-time discovery of this study was an increase in stress proteins in response to HIT training indicating a stress response on the body (although this was not significant).
My input: The main power of this study is that the even though the 2 groups performed different types of endurance training, the researchers matched the groups to perform the same intensity, duration, and work performed. Without doing that, it would have been very difficult for them to conclude that HIT and continuous running show similar molecular responses. It bothers me that the intervals were not the usual ones prescribed for exercise protocols in studies (4-6 times of 30 seconds all out cycling/sprinting). My only critique comes with the time. When matching for time, the HIT group exercised for 18 min of sprinting and 18 min of recovery plus a warm up and cool down period totaling 50 min. The continuous running group did 50 minutes without a warm up and cool down. If they took the biopsies after the sprints were finished and not after a cool down, they may have seen responses similar to what they hypothesized. It is also worth mentioning that this study is short-term and it is not yet known the responses to long-term endurance training of this variety. Other than that, this is the first study to show that following a short bout of endurance exercise, there are similar responses in the mitochondrial of muscle between both HIT and continuous running. It seems that for now, both are sufficient in making you a better athlete.