September 17, 2012
Nutritional regulation of muscle protein synthesis with resistance exercise: strategies to enhance anabolism.

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.


MPS after resistance 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. 

High vs low load

Protein source


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.

Dose

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. 


There you have it.  Now, I’m off to eat some beef.

September 12, 2012
Aerobic Exercise Alters Skeletal Muscle Molecular Responses to 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.

Lundberg et al Med Sci Sports Exerc. 2012 Sep;44(9):1680-8.

August 10, 2012
Protein Ingestion before Sleep Improves Postexercise Overnight Recovery

"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).

Conclusion:

  1. Casein protein at bedtime is effectively digested and absorbed which would lead to an increase in available amino acids from blood plasma overnight
  2. 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.


Res et al Med Sci Sports Exerc. 2012 Aug;44(8):1560-9.

June 20, 2012
Sex-based comparison of protein synthesis following resistance exercise.

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.

West et al J Appl Physiol. 2012 Jun;112(11):1805-13 

April 1, 2012
Exercise Induced Muscle Damage and Hypertrophy

"Bro, how can I put on some mass? I’m a hard-gainer."  "I need some more muscle, I’m too skinny."  "I’m lifting hard several times a week but I just can’t add any size".  Sound familiar?  Luckily, a group published an excellent review in the NSCA journal a few weeks ago on exercise induced muscle damage and it’s association with muscle hypertrophy.  Sparing you the molecular science as much as I can, I’ll highlight for you the key practical findings which support the recommendations that I give to people for training as well as incorporate in my own routines.  An all muscle review.  I’m drooling.  Women can take away from this too because there is nothing sexier than a girl that can deadlift her own body weight.  Right, men? Right.

When we talk about exercise induced muscle damage (EIMD) most scientific studies look at eccentric exercise.  That is to say, the negative portions of the rep.  For example, if you’re doing a bench press, it is the portion that you’re lowering the weight down.  This eccentric portion has been shown to display the most damage to the muscle.  Looking at meta-analyses on the topic, it is clear that eccentric exercise is superior to inducing gains in muscle mass rather than concentric and that optimal exercise-induced muscle growth is not attained unless eccentric muscle movements are performed.

So what is EIMD exactly?  When we’re talking about skeletal muscle damage it is actually shearing of myofibrils (the smallest contractile units of the muscle).  Subsequently, this causes damage to the membrane of the cells which disrupts the flow of calcium.  When the tearing destroys the membrane and calcium levels are tampered with, you get a decrease in muscle force, swelling, and eventually the lovely friend DOMS (delayed onset muscle soreness).  

"Bro, how can I get rid of the DOMS?". One proposed way to attenuate this response is what is described as the repeated bout effect.  Basically it is adaptation of the muscle to the next training session.  The authors note that the arm muscles appear to be more predisposed to EIMD than the leg muscles when taking into account this effect.  Repeating the same routine the next time around will not elicit the same response as the previous because the body has adapted.  Thus, attenuating DOMS for the next session.


"Bro, how can I increase my satellite cells in my muscle? You know, the stem cells of muscle, brah."  Satellite cells donate their nuclei to existing muscle fibers, which aid in their ability to synthesize new contractile proteins.  When the muscle grows the ratio of nuclear content to fiber mass stays the same.  Therefore, to put on muscle long-term, it would be essential to add new nuclei to the muscle.  Damaged fibers require new nuclei to repair.  Therefore, satellite cells are necessary for muscle repair but it is still not entirely known how much of a role this has in hypertrophy.  Although it is important to note that this process is regulated by an enzyme COX-2, deemed necessary to achieve maximal skeletal muscle hypertrophy in response to weight training.  However, non-steroidal anti-inflammatory drugs (NSAIDs) such as Ibuprofen (Advil) or Acetaminophen (Tylenol) block COX-2, which in turn blunts the satellite cell response, which in turn blunts hypertrophy.


"Bro, what about my hormones so I can get SWOLE?".  When we talk about natural hormonal signaling involved in muscle growth we’re talking about insulin-like growth factor 1 (IGF-1).  One form of this growth factor is primarily responsible for compensatory hypertrophy.  A target of this factor has been shown to be greater in eccentric contractions than isometric but this is still not certain.  In addition, IGF-1 has been shown to increase rates of protein synthesis.

"Bro, what about the sick pump?"  There is a novel theory by which EIMD may induce hypertrophy by increasing the intracellular water content.  Cell swelling = getting SWOLE (in a scientific meaning).  This is due to pressure against the cell membrane which leads to reinforcement of the structure.  There are specific sensors that respond to the stretch in the membrane.


"Bro, I just annihilated my arms, I won’t be able to shampoo my hair for a week."  So far there is no true direct cause and effect relationship established between EIMD and hypertrophy.  There does however exist a threshold beyond which more damage does not elicit a greater effect on hypertrophy.  The great 8 time Mr. Olympia Lee Haney is known best for saying, “stimulate, don’t annihilate.”  

"Bro, what about lifting heavy ass weight?"  In the plethora of studies looking at hypertrophy-oriented routines, they all use submaximal intensities of 65%-85% of a person’s one-rep max and that similar anabolic responses are found for programs that are >90%.


"Bro, what about running and lifting? I don’t want to get small."  Finally, this review touches upon a "switch" whereby signaling can be shuttled from a catabolic endurance gene activation and an anabolic resistance dominant state and is specific to the type of training you are performing.  Muscle damage is not sufficient enough to override the endurance switch once it is activated.

Taking all the text in bold, I will now finally outline for you the practical messages from this review that I suggest and deploy in my own training to maximize muscle growth.  Let’s got from the lab to the gym.

  1. Eccentric portions of the rep are superior in inducing damage and increases in muscle mass.  Always make sure you are slowly controlling the weight on the negative portion of the rep.  Even try to add some negative only sets in your routines where someone helps you completely with the concentric and you slowly lower the weight for a count of 4-10 seconds.
  2. The arm muscles are more predisposed to EIMD than the legs.  Don’t be afraid to train your legs with high volume, a lot of sets and a lot of reps to induce growth.  Even training them twice a week if you feel you really want to add size to them.  They can handle the punishment since you walk on them daily.
  3. NSAIDs blunt the response of the enzyme that initiates the signal to increase muscle size.  Try to avoid Advil, Tylenol, etc even if you are very sore from a training session as much as you can.  
  4. Cell swelling may be responsible for an increase in muscle size.  Always try to focus on getting a complete stretch of the muscle on every set as well.  This is important because the greater the stretch, the more you can squeeze the muscle at the end of the movement.  Also, focus on achieving a maximal pump to really stretch the fascia of the muscle even further.
  5. Stimulate, don’t annihilate.  A moderate amount of damage is needed for growth but more than this will not maximize the hypertrophic response.
  6. Focus on controlling the weight first and the actual weight on the bar second.
  7. Once again as I’ve said before, if possible, it may help to separate endurance activities and resistance activities.
  8. Finally, consider changing your routine often due to the repeated bout effect to not allow your body to continually adapt to the same stimulus over and over again.  This is even more important in people that are highly trained and want to keep accumulating muscle.
There you have it.  All the best in your getting swole endeavors, brah [or girl]
Nick

March 1, 2012


Here is what a gene microarray looks like.  In this image, there are 824 genes that were scanned during resistance exercise; in this case, bicep curls.  The red are higher levels of mRNA and the green are lower levels.  It’s amazing, although sometimes quite messy in this case, what we can now do in science.

What this group found is that resistance training blunts genes involved in immune responses by minimizing expression of genes involved in the recruitment of immune cells while simultaneously upregulating genes responsible for inflammation.


In addition, resistance training blunted genes involved in glucose metabolism, mitochondrial structure, and oxidative phosphorylation.  This makes sense due to the specificity of the training.  Resistance training would not require the upregulation of genes involved in these processes because it is not an endurance type activity.  For this reason, I always recommend trying to separate sessions in the gym of weight training and cardio as much as possible because they clearly upregulate and downregulate different genes.  It may be detrimental to the specific adaptive training response if both are done around a similar period, but this is yet to be shown to my knowledge.  Some studies were published on this but I would still say it’s just merely a working hypothesis for now.






(Gordon et al J Appl Physiol.2012 Feb;112(3):443-53. Epub 2011 Nov 3.)

Here is what a gene microarray looks like.  In this image, there are 824 genes that were scanned during resistance exercise; in this case, bicep curls.  The red are higher levels of mRNA and the green are lower levels.  It’s amazing, although sometimes quite messy in this case, what we can now do in science.
What this group found is that resistance training blunts genes involved in immune responses by minimizing expression of genes involved in the recruitment of immune cells while simultaneously upregulating genes responsible for inflammation.
In addition, resistance training blunted genes involved in glucose metabolism, mitochondrial structure, and oxidative phosphorylation.  This makes sense due to the specificity of the training.  Resistance training would not require the upregulation of genes involved in these processes because it is not an endurance type activity.  For this reason, I always recommend trying to separate sessions in the gym of weight training and cardio as much as possible because they clearly upregulate and downregulate different genes.  It may be detrimental to the specific adaptive training response if both are done around a similar period, but this is yet to be shown to my knowledge.  Some studies were published on this but I would still say it’s just merely a working hypothesis for now.
(Gordon et al J Appl Physiol.2012 Feb;112(3):443-53. Epub 2011 Nov 3.)

January 5, 2012
Blood Flow Occlusion Training

I got this question from Chris a few months back and was hesitant to answer it quickly (sorry Chris) because, like him, I was skeptical on the studies and waiting for something new to be published.  Well something just came up last month from a review in MSSE. 

Intro: Chris wanted to know what I thought about Blood Flow Occlusion Training, which is simply putting a band (similar to when you get your blood pressure measured) around a working muscle group in order to restrict the blood flow in hopes of increasing protein synthesis in that area.  It sounds crazy to work, right?

Results: Well researchers report that at low intensities (20%-50% of one rep maximum) plus the occlusion, you can get a similar increase in muscle size and strength as traditional, high-intensity resistance exercise.  The group that wrote this review reported a 46% increase in muscle protein synthesis after an acute bout of resistance exercise with occlusion, similar to that as standard high-intensity resistance exercise.  They also reported this muscle protein synthesis was coupled to activation of mTOR (specifically complex 1), which is a protein associated with activation of protein synthesis.

Discussion/How it works:  When you restrict blood flow to an area the body compensates by increasing the strength of blood flow to that limb.  Eventually, the area will build up metabolites from the exercise that cannot be taken away due to venous flow being occluded.  It is thought that this is the reason/stress that creates the internal environment in the working muscle that can create the response of increases in protein synthesis.  For the molecular junkies, scientists add that occlusion training also decreases proteolytic (breakdown) genes FOXO3A, atrogin, and MuRF-1 8 hours after exercise.  However, there were no reported differences in genes between conventional resistance exercise and bloodflow restricted 3 hours post-exercise.

Conclusion:  At this point, the authors suggest that there are still no explanation for the exact cellular mechanisms responsible for the increases in muscle growth following blood flow restriction training.  All that can be said is that it is showing promise in similar increases in mTORC1 in that of conventional resistance training methods.

My input:  Am I going to try it? Probably not.  Even if it works it is still not shown to be better than standard resistance training protocols.  If I were to prescribe this, I would do so to healthy older individuals (age 50 or above) who simply cannot handle the weights of people in their physiological prime since this method has weight intensities of 20-50% 1RM.

August 9, 2011
Integrins and eccentric exercise induce hypertrophy.

A muscle study, my kind of study.  If you want to add some muscle, I can make it your kind of study too.

Introduction:  Eccentric training (the negative or lowering of the weight) induces significant mechanical damage to the intregrity of skeletal muscle to the extent that increase the size of the muscle more than that of concentric exercises.  Mechanical stimuli work off of the mTOR pathway.  To keep it simple (which the mTOR pathway is not), stimulation of this pathway causes increased protein synthesis, muscle growth.  Muscles sense mechanical strain (duh, Nick) but scientists are now taking steps to understand singaling pathways involved in this strain.  Integrins are “heterodimeric transmembrane receptors that allow cells to adhere to the extracellular matrix providing the opportunity for cellular stabilization and the ability to transmit mechanical and chemical information from the outside of the cell to the inside.”  That is to say, integrins are cell glue, if you will.  One such intregrin, A7Beta1, was found to increase in myopathy cases such as muscle dystrophy; thus, it is protective of the muscle.

Hypothesis:  the presence of the α7 integrin would increase fiber hypertrophy and whole muscle size following repeated bouts of eccentric exercise.

Methods:

4 weeks of eccentric training via downhill running in a mice model overexpressing this integrin.

Results:  myofiber CSA (cross-sectional area), whole muscle CSA, relative muscle weight, myofibrillar protein content, and maximal isometric force were significantly elevated in α7Tg muscle following training compared to sedentary counterparts. mTOR was also activated.  It is important to note that this training protocol did not induce muscle hypertrophy in normal mice but solely in the mice overexpressing this integrin.

Conclusion:  The α7Beta1 integrin may represent a critical intrinsic factor in muscle that initiates signaling events leading to efficient exercise-induced muscle growth.

My input:  The purpose of this blog is to provide information that exercise is not just for weight loss but like the ACSM states, “exercise is medicine”.  Here is another key study linking exercise training to increases in hypertrophy (which is great for healthy individuals) but also has the biomedical aspect that carries over to patients with muscular dystrophy.  Exercise science continues to take strides to rival those of researchers in biochemistry and biology.

 Zou et al J Appl Physiol August 2011

June 29, 2011
Hormonal Responses to Resistance Exercise during Different Menstrual Cycle States

This one’s for the ladies, especially those that aren’t afraid to lift weights, aka, my type of women.  Anyways…

Introduction:  Little is known about anabolic hormone responses to resistance exercise in different phases of the menstrual cycle.  Therefore, Japanese researchers wished to see how resistance training can effect different anabolic responses which eventually lead to physiological adaptations to exercise.  To do so, they examined changes in 2 phases of the menstrual cycle; the early follicular (EF) and midluteal phases (ML) in eumenorrheic (normal) young women as well as young women with menstrual disorders (oligomenorrhea and amenorrhea OAM). 

 Hypothesis:  Changes in ovarian and anabolic hormones in response to an acute resistance exercise are influenced by menstrual cycle phase and state.

Results:  Serum estradiol and progesterone increased in the ML phase but not the EF or OAM.  Serum growth hormone increased after exercise in both the EF and ML phases; however, this was not present in the OAM group.

Conclusion:  The responses of anabolic hormones to acute resistance exercise were different depending on the menstrual cycle state, suggesting that menstrual cycle state may influence the exercise training-induced skeletal muscular adaptation.

My input:  Perhaps it is time that women start planning their resistance training around the ML, a.k.a. the periovulatory phase of their menstrual cycle to optimize the skeletal muscle adaptations to weight lifting.  It is interesting to note in many biopsychological studies, that this is the also the phase where woman find themselves most attractive to “rugged” men, meaning their hormones are higher(and you know what happens next).  This study did a good job of controlling for the many factors that influence hormonal responses to resistance exercise (e.g., sex, age, fitness level, nutritional status, exercise variables).  Interestingly, the OAM group did not have a GH response but they did attribute this to low levels of circulating estradiol, which is thought to stimulate GH secretion.

Nakamura et al Med Sci Sports Exerc. 2011 Jun;43(6):967-73.

June 23, 2011
Acute Loading and Aging Effects on Myostatin Pathway Biomarkers in Human Skeletal Muscle After Three Sequential Bouts of Resistance Exercise.

Introduction:  Myostatin is a negative regulator of skeletal muscle mass by maintaining satellite cells (the stem cells of muscle) in a quiescent state.  That is to say, when myostatin gene expression levels are high, skeletal muscle atrophy (loss in size) will occur.  Not much is known about myostatin levels in the older adult population and this is significant in the prevention of sarcopenia, or age-related loss in muscle mass.  To investigate this, researchers recruited young (mean age 21) and old (mean age 66) men and measured their basal levels of myostatin as well as the levels of various other precursor markers during three different bouts of resistance exercise.

Hypotheses:  The expression of the myostatin pathway-related genes would be upregulated in older compared with younger men.  However, following acute resistance exercise, the pathway-regulated genes will be downregulated to a greater extent in older compared to younger men.

Results:  Myostatin mRNA levels were decreased in older men after resistance exercise and baseline FST & FSTL3 (inhibitory factors of myostatin) were higher in older men as well.  There were no differences in baseline values between older and younger men.

Conclusion:  Older men have a more favorable internal environment for muscle growth than younger men by possessing lower levels of myostatin after resistance exercise.  This finding could be a protective mechanism to prevent further muscle wasting with aging and preserve muscle mass in older individuals.

My input:  Get your dad to hit the weights in the gym.  He has a more favorable muscle growth environment in his genes than you do.  This is a great way to preserve his muscle and keep his metabolic rate higher to prevent unwanted weight gain.

Dalbo et al J Gerontol A Biol Sci Med Sci. 2011 Jun 10