3 Tips for Muscle Hypertrophy (Bigger Muscles): Research Review for November 2009

Jack Leon[between 1910 and 1915]

Just a few very cool studies this month and see my comments on how you can apply these for increased athletic performance on the field and in the gym!  Let’s roll

Local NSAID infusion inhibits satellite cell proliferation in human skeletal muscle after eccentric exercise

Despite the widespread consumption of nonsteroidal anti-inflammatory drugs (NSAIDs), the influence of these drugs on muscle satellite cells is not fully understood. The aim of the present study was to investigate the effect of a local NSAID infusion on satellite cells after unaccustomed eccentric exercise in vivo in human skeletal muscle. Eight young healthy males performed 200 maximal eccentric contractions with each leg. An NSAID was infused via a microdialysis catheter into the vastus lateralis muscle of one leg (NSAID leg) before, during, and for 4.5 h after exercise, with the other leg working as a control (unblocked leg). Muscle biopsies were collected before and 8 days after exercise. Changes in satellite cells and inflammatory cell numbers were investigated by immunohistochemistry. Satellite cells were identified using antibodies against neural cell adhesion molecule and Pax7. The number of Pax7+ cells per myofiber was increased by 96% on day 8 after exercise in the unblocked leg (0.14 ± 0.04, mean ± SE) compared with the prevalue (0.07 ± 0.02, P < 0.05), whereas the number of Pax7+ cells was unchanged in the leg muscles exposed to the NSAID (0.07 ± 0.01). The number of inflammatory cells (CD68+ or CD16+ cells) was not significantly increased in either of the legs 8 days after exercise and was unaffected by the NSAID. The main finding in the present study was that the NSAID infusion for 7.5 h during the exercise day suppressed the exercise-induced increase in the number of satellite cells 8 days after exercise. These results suggest that NSAIDs negatively affect satellite cell activity after unaccustomed eccentric exercise.

My thoughts

Very interesting study, but I am not convinced that NSAIDs are actually bad for muscle growth.  The data about 2-3 years ago, said that they were bad for muscle hypertrophy; but newer data is not pointing that way.     The eagle observer would notice that this study showed a negative effect on satellite cells, which would say that it is bad for muscle growth.  The downside is that muscle growth was not measured in this study.  Muscle can get bigger by various mechanisms, and while satellite cells is one way, it is not the only way.  Satellite cells are the little guys that hang out at the end of the muscle fibers and work to repair them from damage.   So for now I would not automatically reach for NSAIDs if you have muscle soreness, but if you have to, it is probably not affecting growth too much.  If people are interested, drop a note in the comments and I will do a blog post just on this.

Working around the clock: circadian rhythms and skeletal muscle

The study of the circadian molecular clock in skeletal muscle is in the very early stages. Initial research has demonstrated the presence of the molecular clock in skeletal muscle and that skeletal muscle of a clock-compromised mouse, Clock mutant, exhibits significant disruption in normal expression of many genes required for adult muscle structure and metabolism. In light of the growing association between the molecular clock, metabolism, and metabolic disease, it will also be important to understand the contribution of circadian factors to normal metabolism, metabolic responses to muscle training, and contribution of the molecular clock in muscle-to-muscle disease (e.g., insulin resistance). Consistent with the potential for the skeletal muscle molecular clock modulating skeletal muscle physiology, there are findings in the literature that there is significant time-of-day effects for strength and metabolism. Additionally, there is some recent evidence that temporal specificity is important for optimizing training for muscular performance. While these studies do not prove that the molecular clock in skeletal muscle is important, they are suggestive of a circadian contribution to skeletal muscle function. The application of well-established models of skeletal muscle research in function and metabolism with available genetic models of molecular clock disruption will allow for more mechanistic understanding of potential relationships.

My thoughts

Very cool study and the first I have seen in this area.  The age old question of what is the perfect time to lift has been around for a long time.   From what I have seen, there does not seem to be a perfect time.  The perfect time is when you can get to the gym and seems to be highly individual.  First priority is to get there, lift the weights and then later worry about finding the best time.  If I could set up my perfect schedule it would be to lift at 3pm in the afternoon.   Keep in mind that if you have a contest, say a powerlifting meet that start at 9am, you may want to do some lifts at that time in practice just to see how your body reacts.

For now, get to the gym first.

Translational signaling responses preceding resistance training-mediated myofiber hypertrophy in young and old humans

While skeletal muscle protein accretion during resistance training (RT)-mediated myofiber hypertrophy is thought to result from upregulated translation initiation signaling, this concept is based on responses to a single bout of unaccustomed resistance exercise (RE) with no measure of hypertrophy across RT. Further, aging appears to affect acute responses to RE, but whether age differences in responsiveness persist during RT leading to impaired RT adaptation is unclear. We therefore tested whether muscle protein fractional synthesis rate (FSR) and Akt/mammalian target of rapamycin (mTOR) signaling in response to unaccustomed RE differed in old vs. young adults, and whether age differences in acute responsiveness were associated with differences in muscle hypertrophy after 16 wk of RT. Fifteen old and 21 young adult subjects completed the 16-wk study. The phosphorylation states of Akt, S6K1, ribosomal protein S6 (RPS6), eukaryotic initiation factor 4E (eIF4E) binding protein (4EBP1), eIF4E, and eIF4G were all elevated (23–199%) 24 h after a bout of unaccustomed RE. A concomitant 62% increase in FSR was found in a subset (6 old, 8 young). Age x time interaction was found only for RPS6 phosphorylation (+335% in old subjects only), while there was an interaction trend (P = 0.084) for FSR (+96% in young subjects only). After 16 wk of RT, gains in muscle mass, type II myofiber size, and voluntary strength were similar in young and old subjects. In conclusion, at the level of translational signaling, we found no evidence of impaired responsiveness among older adults, and for the first time, we show that changes in translational signaling after unaccustomed RE were associated with substantial muscle protein accretion (hypertrophy) during continued RT.

My thoughts

There is more and more research coming out on hypertrophy in older folks.  My good buddy Carl Lanore likes to say “muscle is metabolic currency, so go to the gym and make a deposit today,’ and I totally agree.   It appears that muscle size is harder to come by as we age; but how much harder is still not clear.  Early studies showed that it was difficult, but recent data like the one above show that maybe there is not much difference.  Again, this is a 16 week study (which is pretty good for most studies) and note that they used NOVEL exercises.  I think this is a key point.  You need to give the body a REASON to adapt.  It also showed that strength increased, so the old people in the study were not all show and no go!

What 3 Tips Did We Learn Today?

1. NSAIDs may not be as bad for muscle hypertrophy as we once thought

2. Timing may become a bigger issue in the future, but for now get to the gym first

3. If hypertrophy is your goal, you need to “surprise” the muscles.  Now don’t go all crazy with the Weirder “confusion” principle, as plain old overload (doing more work over time) is a very powerful stimulus as the work load is novel.  I am a big fan of adding volume since it allows you to manage fatigue (Charles Staley’s ears are burning) and keep doing perfect reps.

Any questions/thoughts, let me have it in the comments

Rock on

Mike T Nelson

PS

You will have to come back here on Monday as you will have to see what I am posting.  The feedback on it so far has been crazy (both good and bad crazy),  Stay tuned!

Morphological Hypertrophic Muscle Adaptations (aka, Mechanisms Behind “I Wanna Get Hyoooge!!”)

Pop your head into just about any gym in America, and observe the male population (especially the younger ones) train. While the training methods are interesting in themselves, the common battle cry of the young Arnold wannabes is usually the same “I Wanna Get Hyoooge.” In an effort to explore the mechanisms behind the scenes in the body to help out these “bros” it is time to board the magical muscle mystery tour. Tour stops include a drive by of the nervous system, muscle fiber types, and how muscles adapt to exercise to get bigger and badder (as in a Michael Jackson “bad” is now good way).

Before we dive in head first into this, we need to do a short little anatomy tour. They say a picture is worth a thousand words, so check out figure below.

This time around I will spare you all the details on the exact names of each, but notice how a single fiber at the end goes into another group of fibers and then THAT group goes into another group until we are all the way up to the muscle itself. Muscle fibers can be broadly defined as type2 fast twitch or type 1 slow twitch (8). Fast twitch (type 2) fibers can produce more force, but they don’t last as long (26). Think of an NFL lineman. He can produce a ton of force to knock you into next week, but it is unlikely he will be chasing your around the block or very far at all. Type 2 (slow twitch) muscle fibers are like the slower cousin to the type 2, think energizer bunny. They can’t produce as much force, but they keep going and going and going and going………..

Remember that the nervous system is the head cheese, numero uno, el presidente, the commander in charge that controls all muscle movements. The nervous system also controls which fibers are type 1 or 2! Buller et al. (9) in 1960, carefully did the ole “switcheroo” on cats and switched nerves and a type 2 muscle fiber with a new type 1 NERVE now took on the properties of a type 1 muscle fiber! Think of this as “what the commander says goes.”
Another key point is that “living systems are build up through use and atrophy (get smaller) with disuse.” So when you are in the gym blasting away, you are actually making your muscle SMALLER! Yikes! The good part is that your body responds by BUILDING up those damaged fibers during the recovery period (33). So next time you do a similar exercise, the body has “new and improved” muscle tissue to better handle the damage. Pretty sweet!

Muscle Growth Time
Skeletal muscle is a very dynamic tissue capable of adapting to the stress placed on it. The process of exercise-induced adaptation in skeletal muscle involves a multitude of signaling mechanisms all the way down to the genetic level, ultimately putting together strings of amino acids to form new proteins in the form of more muscle tissue (10). Whooo ha, and the gym “bros” rejoice!

As mentioned, muscle growth is commonly referred to as “hypertrophy” (34) or more accurately as an increase in muscle fiber SIZE. How does this happen? While a complete answer to that question is beyond this short article, what do you think are some key processes? “TESTOSTERONE!” Good guess and there is a fair amount of data to support this (16, 17, 29, 30), there is also data (although less) to show that in castrated (denutted—youch!!!) animals (yeah I know it was not done in humans but do you want to volunteer for those studies?) are still able to increase muscle size despite having testosterone levels at very low levels (22, 24). “NUTRITION!” Yes, there is no denying that nutrition especially extra calories and protein are needed for muscle hypertrophy (11, 13, 19) but even in caloric restriction muscles can still get bigger (12). “INSULIN!” While insulin is the most anabolic (building) hormone in the body, it is not required either (7). (Side note, I am using the term “anabolic” in the physiologic sense where it is taking small things and making bigger things with them. This can be proteins into new muscle or fatty acids into new fat storage around your waist. And yes, too much insulin can make you a fat bastard). So the muscle building process is a complicated one.

How Do These Genes Look
Further down the hole, we have a whole slew of molecular signaling guys, some newly discovered like Mighty that can dramatically influence muscle growth. Mighty is a downstream metabolite of myostatin. Most have probably heard of myostatin now or seen the huge picture of the Belgium Bull.

Belgian Blue Bulls (say that fast three times in a row) have a mutation in the myostatin gene that produces a truncated, ineffective form of the protein (20), so in English there is almost no myostatin hanging around. The absence of myostatin allows unchecked muscle growth and interferes with fat deposition; the result is a lean, “double-muscled” bull. Yikes! Remember that LESS myostatin = MORE muscle.

The new kid on the block now is Mighty. Mighty is expressed in a variety of different tissues but appears to be specifically regulated by myostatin in skeletal muscle. Overexpression of Mighty in certain cells (ok, C2C12 cells if you really want to know) results in enhanced and accelerated differentiation and hypertrophy of myotubes (this is good for muscle growth, trust me) and leads to increased and earlier expression of MyoD and insulin like growth factor II (IGF-II) (both are good for muscle growth) (23).

Enough Biochem Yacking already
So I spared you from a detailed talk on Interleukin-4 (IL-4) and interleukin-13 (IL-13) that are involved in getting hyoooge (27), so be thankful! Watch out—Geek alert! Serrano et al. (28) recently showed a role for IL-6 in hypertrophic muscle growth and provide mechanistic evidence for the contribution of satellite cells to this process, in our fury friends the mouse.

So back to our irregularly scheduled program. So far we know 1) nutrition is key-calories and protein are needed to build muscle 2) we need a stimulus—weight training works well here (31) 3) certain hormonal and biochemical changes need to take place—from hormonal changes down to even the molecular level.
Shut Up Already and Tell Me HOW to Get Hyoooooooooge!
During short term studies of less than 10 weeks, it was shown that type 2 fibers hypertrophy (get bigger) much faster from training than their slow cousins the Energizer bunny type 1 fibers (1). MacDougall et al.(21) however investigated a longer time period of 5–6 months of heavy resistance training (weight lifting) in seven males and demonstrated a significant cross sectional increase in type 2 AND type 1 fibers; so long term it appears that BOTH fiber types can increase in size. Take home message, use a wide variety of reps.

Damage Plan
The goal of some dedicated Arnold wannabes is to destroy tissue! No pain no gain! Go hard or go home! Is there any research to support this method if we can get hyoooooooooge? There is actually some evidence to support this notion. Goldspink about 30 years ago proposed that if you literally tear the muscle fiber in half (these would be very small tears of course), that this may promote splitting of the muscle fibers once the body goes to work repairing those fibers; thus resulting in more fibers over time. More fibers= more siz
e. The fancy word associated with increasing muscle fiber NUMBER is hyperplasia. The downside is that this phenomena is highly debatable with virtually the studies being conducted on animals (primarily cats and birds), so how it applies to humans is not currently known (2-6, 15, 18, 32).

We know that eccentric (lowering a heavy weight) can scramble the muscle fibers (induce lots of damage) and it appears that fiber disruption induced by habitual weightlifting exercise is essentially repaired after 5 days of inactivity in trained men (14) and oxidative stress indices changed significantly with most peaking at 48 hours (25).

What does any of this mean?
Although data is somewhat limited on the “destroy tissue” approach in relation to hypertrophy there is enough to support the idea for muscle hypertrophy, but keep in mind that your recovery time may be longer with this approach. Your muscles get bigger OUTSIDE the gym when they are repairing!

Conclusion
Thus ends our very brief ride on the magically, muscle mystery tour! I hoped you have enjoyed the tour and kept your hands inside the bus at all times. We got to spend some time in the land of the nervous system, fiber types, stimulus for adaptation (aka weight training), and the adaptation process itself. The take away is that muscle hypertrophy is a complicated process and our best bet in the quest for huge-dom is 1) excellent nutrition with a surplus of calories and proteins and 2) consistent weight training with adequate time for recovery; especially if eccentric movements are used to induce muscle damage.
Time to get to the gym!

Mike T. Nelson has a BA in Natural Science, a MS in Mechanical Engineering (Biomechanics) and is currently a PhD student in Kinesiology (Exercise Physiology) at the University of Minnesota. His research interests are on the effects of energy drinks on metabolic health and the nervous system.

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