Stimulate, Supply, and Signal
by Kelly Baggett Iron Magazine
Contrary to popular belief, training is not the only way to stimulate muscle growth. In fact the biggest growth spurts for the average person occur in the absence of any intention to increase muscle mass (adolescent development and puberty).
A good example to illustrate the various ways of stimulating hypertrophy is with arm training. Everyone says you need to perform whole body compound movements and gain 10-15 lbs. overall scale weight to gain an inch on your arms right? However, you’ll routinely see guys at the gym who increase their arms by an inch or more without gaining a pound. You’ll see plenty of guys with big upper bodies who probably don’t even know what a deadlift is. You know they didn’t start out big because their lower bodies are skinny. Same thing for guys with big arms, but rather normal sized upper bodies and pencil necks. Is this just genetics or what’s going on here?
Additionally, you have “gurus” saying that it doesn’t take “extra” nutrition to grow muscle. They give examples of guys who gain significant amounts of muscle eating 1500 calories per day of fast food and pop tarts. On the other hand, you have guys who won’t gain an ounce unless they really tie on the feed bag and take a hardcore no holds barred attitude when it comes to spending hours at the dinner table and driving that scale weight up. So what’s going on here?
To understand all this it helps to understand the 3 keys for growth:
A. Stimulation – Training (load, density, volume etc)
B. Supply (nutrient and protein intake)
C. Signaling (anabolic hormones, testosterone, insulin etc.)
Training stimulates growth, eating supplies material for growth, and various hormones signal growth to occur.
Training stimulates muscles to grow. Not exactly a “cutting edge” observation, but any work you do that your muscles are not accustomed to will cause some protein breakdown in your muscles which, assuming that nutrient supply and anabolic signaling are optimal enough, your body will repair the damaged muscle with a little more protein to make them a little bigger then before. Regardless of how you create the stimulation (traditional lifting, isometrics, strongman, manual labor, partials, rubber bands, lifting rocks, pushing cars, negatives, or whatever), all physical work creates tension and greater levels or volume of mechanical tension then what your muscles are accustomed to stimulates protein breakdown. The more total muscle cells you have in a given muscle group, the greater potential growth improvements you tend to have in that muscle. Although the stimuli can vary, a muscle can only respond to so much stimulation workout to workout. In other words, if you can stimulate growth from 1 or 2 sets, it’s not like doing 20 sets will enable you to grow 10 times as fast
Supplying Material for Growth
A pound of muscle requires a little more then 700 calories to manufacture. Under certain situations, the body can and will sometimes get those calories from the breakdown of energy from stored bodyfat, or it can get them from your diet, but the energy has to come from somewhere. Since muscle is made up of 70% water and a pound of muscle only contains about ~136 grams of protein it might make sense that if you simply eat maintenance calories and an additional 20 grams of protein per day that you’d consistently gain about a pound of muscle per week. But it’s not quite that simple and here’s why:
Imagine you’re locked up in a cage in a concentration camp and you’re totally dependent on someone else to bring you food. Ok. Let’s say you’re in this concentration camp and have a choice of whether to stay the same size and burn up the same amount of energy or get bigger and use up more energy. Now, remember, you never know when the next meal will come or how much food will be contained in each meal. One week you might go 3 days without eating and another week you might get 3 meals per day every day. Would you choose to get bigger and increase your daily energy needs when a period of starvation might soon follow? Probably not.
Your Muscles Tend To Assume A Food Shortage Is Around The Corner – Unless You Tell Them Otherwise
The relevance of this is that your muscles are the same way. If your muscle cells get bigger, this increases your daily energy needs. Your body is always striving to operate as efficiently as possible in the event that a famine might be just around the corner. Bigger muscles mean greater food requirements for you, which would not be a good thing if a food shortage is just around the corner. Thus, in order to grow, a muscle needs “assurance” or a strong “signal” that says, “Ok I’m very well fed so I can get bigger and not have to worry about an impending nutrient deficit.” What sends that signal? Mainly a “chronic” nutrient surplus, which means full glycogen stores and a chronic influx of amino acids (protein)
Genetic Variability and Experience
Now, based on the strength of your “growth signaling” network (a.k.a. genetics – which I’ll cover next), and how far above your baseline level of muscle mass you are, in order to get that chronic nutrient surplus it’s often necessary that you eat more then just maintenance calories and a few extra grams of protein per day. Some people need to jack their calories and protein intake way up into the stratosphere in order to send that “fed” signal and supply enough excess material for growth, while others might grow on maintenance or below maintenance calories with little attention paid to nutrition. However, there is no doubt that a good supply of nutrients allows the body to maximize the stimulation response (grow faster). If that weren’t true, then guys who consciously pushed the scale weight up wouldn’t gain so much more muscle then the measly 3 or 4 pounds of muscle per year that natural bodybuilders gain when trying to stay ultra lean year around.
One last point relevant to this topic: Even in the absence of exercise, supplying excess raw material (food and protein), can cause some growth too occur. In one study, sedentary people overfed 1000 calories per day for 100 days gained 1/3 of their newfound scale weight as muscle.
Signaling Growth To Occur
The last “S” is hormonal signaling. Various anabolic hormones such as testosterone, insulin, IGF-1 etc. stimulate growth to occur. Think of the muscle mass difference between a male and female. It’s all due to hormonal signaling. Think of someone labeled with “good” genetics vs someone with “bad” genetics. Again, the difference is mostly hormonal. People naturally vary in their hormonal signaling. Genetic freaks tend to have much better hormonal profiles. How powerful is hormonal signaling? Even in the absence of training, anabolic signaling can cause plenty of growth, which is why the average male gains ~40 pounds of near permanent muscle during puberty even without training. In studies done on steroids, guys who took 600 mg of testosterone and sat on their butt and did no training over an 8 week period of time still gained twice as much muscle (9 pounds) as another group of guys who busted their ass training naturally over the same period of time. (4.5 pounds)
It’s worth noting that the growth that results from eating and the growth that results from anabolic hormones kind’ve go hand in hand. When you eat well and manage your stress levels, the growth is not necessarily just from the food, but from an optimization of your hormonal status which maximizes your hormonal growth signaling.
The relevance of all of this is that if you maximize stimulation, supply, and natural anabolic signaling, you obviously have a superior environment for muscle growth.
Beginners Can Grow Even Without Everything Being Optimized
Initially, you can get a growth response from anything. This is why you can take a sedentary person and have them start lifting, even with suboptimal eating habits and a caloric deficit, and they’ll often still gain some muscle. For example, let’s say a person buys a curl bar and decides to start training their arms a couple of times per week. Initially, even though they might lose bodyweight, they will most likely still be able to gain maybe an inch or so on their arms. That right there would appear to shoot the “15 lbs per inch” theory straight into the ground and it does. Anytime somebody tells you that you need to gain 15 lbs to gain an inch of muscle on your arm consider them full of crap unless they can qualify that statement and tell you under what conditions that might be necessary.
Localized hypertrophy from training is really just excess repair. The important thing is, there is a limit to how much of that excess repair or hypertrophy the body will create on it’s own unless you start adding in excess raw materials (food), and/or excess anabolic signals (extraneous hormones or the hormones that come from eating). That point will vary from individual to individual so a few will be able to stay at practically the exact same bodyweight and be able to cause significant growth all over or on only one area of the body and some can gain quite a bit of muscle without much intentional attention paid to increasing their nutrition.
Local Stimulation vs Whole Body Stimulation
Ok. Now, the growth stimulation from training (mechanical loading) by itself is also local. You train a muscle group and cause some damage and the body repairs that muscle group with a little more muscle so that it can better deal with the stress next time. In other words, if we’re only referring to growth that results from training, if you train your biceps you’re not gonna get your calves to grow. The only muscle that will grow is your bicep.
So Compound Movements Like Squats Aren’t The Answer?
“But what about these gurus who say the quickest way to get big all over is to do squats?” Well they’re also right in a way. (Assuming good eating). If you train your legs hard your legs will grow. Your chest might also grow from leg training but WILL NOT grow from the mechanical training effect that spilled over from your legs. Growth “spillover”, such as training legs and getting the whole body to grow, tends to occur more from the overall anabolic effect.
The effects from training itself can be localized. However, the effects of eating and/or hormones tend to be more systemic. That means you can’t really relegate their action to just a specific part of the body. They tend to affect the entire body and cause growth all over.
In other words, if you take a sedentary person and overfeed him for 2 weeks he’ll probably gain a few pounds of muscle mass and a few pounds of fat. That muscle will tend to be distributed over the entire body not just in one area. If you give that same person steroid injections he will gain muscle all over his body. If you give him testosterone injections for 6 weeks, AND have him do arm training, he’ll probably gain 10 lbs of lean muscle mass. Even though he only trained arms, the majority of that muscle will be distributed over the entire body.
So What About That 15 pounds For Each Additional Inch On The Arm?
Let’s say a guy starts training, eats maintenance calories, and takes his arms from 13 inches to 14.5 inches and then gets stuck. At this point, he’s gotten all out of the lone “stimulation” signal that he can get. His arms have reached a state of homeostasis. His cells have adapted to the stimulation thrust upon them so he no longer causes much breakdown when he curls and, providing he does change his routine a bit so that he can once again stimulate some breakdown, he still has 2 other problems:
A: With his current diet the amount of nutrients reaching the muscle cells in his arms isn’t enough to provide much extra raw material to stimulate growth.
B: The amount of anabolic hormones circulating throughout his body isn’t enough to “signal” anymore increased protein synthesis in his arms
Clearly, in order to get his arms bigger he either has to eat more food or increase his anabolic hormone levels, both of which affect things systemically. At this point, in order to continue getting his arms bigger, his whole body will have to grow a certain amount to. It so happens that after one reaches their threshold of growth from training alone, the average amount of whole body growth from eating and/or hormones is usually around 15 lbs in order to put approximately one inch on the arms. So, if this guy wanted to get a 15.5 inch arm he’d probably have to gain about 15 lbs of overall scale weight.
If a guy or girl does a lot of squats or other compound movements, not only do they tend to “stimulate” a lot of various muscles, they also tend to stimulate the metabolism in such a way so that more nutrients can be taken in and directed to muscle groups all over. That’s one of the superiorities of compound movements. Nothing really complicated about it.
Explanation for the “Collection of Bodyparts” Syndrome
What’s also interesting is that the muscle generated from training and the muscle generated from anabolic hormones is somewhat different. Certain muscles groups have a greater preponderance of testosterone receptors and tend to develop disproportionately in men vs women or men on steroids vs natural trainees. These muscle groups include the neck and shoulders.
Additionally, a muscle will generally hypertrophy according to where the mechanical strain is highest (towards the muscle-tendon junction). Using anabolics or pubertal muscle growth will cause a more general hypertrophy however as the mechanism isn’t 100% dependent on mechanical strain
If you take a close look at someone who has trained naturally a long time they will often look like a collection of bodyparts probably due in part to this difference. The traps, necks, and deltoids will often appear disproportionately underdeveloped then the quads, chest, etc.
Put Things Together
So, to sum it up. You stimulate growth with training. You supply material for growth with good nutrition. You create a good anabolic signaling environment for growth by maximizing your various anabolic hormones. Your hormonal environment can be maximized by optimizing your training, nutrition, and stress levels. The largest growth increases come from exogenous or pubertal hormones. If you’re natural, past the age of puberty, or female, and you want to overcome those deficiencies, you gotta learn how to correctly apply these keys, which hopefully this article series will teach you how to do.