Testosterone, overall muscle growth, and specific muscle groups

Factual Questions
1

In theory, there is a factual answer, but online you can find a wide range of perspectives.

So, it seems to be a fact that overall muscle growth is limited by testosterone. You can’t get big without it. Manipulate it via steroids and other PEDs, and you can get very big indeed.

But here is an assertion I don’t know whether is true or not: That if you focus on one muscle group, you will use up all your testosterone on that group, and you won’t have testosterone with which to build another muscle group.

Thus, if I am doing massive legwork with squats, for example, my upper body development would suffer. The legs would suck up all the test, and I could have T-Rex arms.

So let me suggest a theoretical case: I do leg press for a year, nothing else. I in theory use all my test on my legs. I have reached my maximum. My legs are, according to the aforementioned assumption, bigger than had I been doing full-body workouts this whole time. Is this really true, however? Or have I just maxed out my test use for the legs alone?

Let’s suppose that I have used all my test on my legs and then start doing heavy upper body while maintaining my leg press routine. IF it is indeed possible for me to use all my test on my legs, then either of the following should happen:

• My upper body grows but my leg press numbers go down. Reason: The test use is spread more evenly across the body.

• My leg press numbers stay constant, but I can’t get my upper body to grow much. Reason: I’ve already built total max muscle on my legs, so I can’t build any more on my upper body.

Yet, what I think would really happen is this: The leg press numbers would stay constant but the upper body would indeed grow. If you stimulate a muscle, something is going to happen. But it seems possible that the preexisting muscle in the legs would hamper upper body growth a bit.

Another possibility is that, while test usage by the body is indeed limited, maxing out a single muscle group would still not use all the test. Thus, if one focused overly on the lower body, one would not use all the test there, and there would still be plenty of room for upper body growth.

Thanks for your insights!

2

IANA expert on this but ISTM that your question is based on a number of assumptions, which go above and beyond just testosterone levels affecting how quickly and completely you can bulk up.

Such as:

[ol]
[li]Testosterone levels is the critical limiting factor in how big someone’s muscles can get. [/li][li]High testosterone levels are also required for maintaining muscle mass[/li][li]Testosterone gets “used” by muscles, and not replenished. So if muscle A needs lots of test, then there’s little left for muscle B. [/li][/ol]

I think these assumptions are questionable, especially the last one.

3

It would seem to be the bottleneck. Protein, calories, and training seem to be the other essential factors, over which we have more control.

This definitely seems to be true. You can’t build up huge muscle on roids, go off the roids, and keep the muscle.

This is not my assumption but basically what my question is: how test gets distributed and used over time. Test definitely gets replenished, but since it is needed to maintain muscle per above, it is unclear how it works per my hypotheticals in the OP.

4

Surely there is some more muscular and endocrinological knowledge on the Dope!

5

  1. Testosterone levels are regulated, just like most hormone levels are, in feedback loops. “Use up” some testosterone to make levels decrease and the hypothalamus responds relasing gonadotropin releasing factor which then causes the pituitary to release FSH and LH which in turn cause more testosterone production increasing it until the hypothalamus relatively turns down production again. Of course other factors impact that feedback loop as well but the basic concept is that testosterone levels are set by the brain given a normal ability for the testes to respond. (Hence why one side effect of giving supplemental, a.k.a. exogenous, anabolic steroids is the brain sending less signal to the testes and the testes shrinking as a result.)

  2. In general heavy resistance exercise, and even moreso moderate to heavy with higher volume increases short term levels of both testosterone and growth hormone in the period immediately after exercise. Theoretically at least lifting hard on squats and deadlift, and the Olys, will augment the impact of upper body lifts as those big whole body lifts are (more likely) a stronger stimulus for those transient increases in testosterone and growth hormone levels after work outs. Exercise does NOT use it up.

  3. Overall muscle growth is limited by lots of factors, including but not limited to testosterone levels I can’t say that I know what the typical limiting factor is but I am not sure I’d believe anyone who said they did without some good citations backing them up.

A detailed review if you want it. (pdf)

6

Thanks for that info, Dseid.

7

Testosterone promotes muscle growth by, among other things, stimulating the production of the proteins used to build muscle and by inhibiting cortisol, which breaks down muscle during recovery. It works “system wide” in the body.

As for using it up, it will benefit whichever muscles are being worked. If you’re working your legs, it will help your legs. If you’re working your legs and upper body, it will help both. It isn’t going to pick and choose and one set of muscles can’t “steal” it from another.

8

Isn’t there a lot more to it than mere testosterone levels? I mean, there are a lot of “hard gainers” out there who aren’t by any means deficient in testosterone.

I always conceived of anabolic steroids as being most akin to what nitrous oxide is to a car- kind of a brute-force approach to getting more out of an engine, and one that’s not terribly good for it, while natural testosterone is more like your intake system- probably not what’s really limiting your car’s top speed in most cases.

AFAIK, testosterone and steroids are more akin to a catalyst than a raw material in muscle-building- in that they increase protein production and block cortisol’s break-down effects. So basically if you super-charge that, you’ll get muscle growth, but it’s not like it’s “used” up, so much as your body’s feedback mechanisms work to flatten the hormone level out.

9

Yes, there’s way more to it than testosterone levels and screwing around with your endocrine system isn’t something to be done lightly or by the ignorant. Bad things can, and do, happen.

Testosterone levels are controlled and maintained by the hypothalamus, pituitary, testicular axis and screwing around with that mechanism isn’t for the simple minded. For example, if you start raising your testosterone levels, your body will start producing more aromatase which will convert the testosterone to estrogen.

Endocrinology isn’t a “let’s have a bash and see what happens” sort of deal. No one should be playing at being a hormone doctor.

10

Another vote for not messing around with your hypothalamic-pituitary-gonadal axis (and not saying anyone here was suggesting such).

Yes there are “hard gainers” and there those who don’t respond effectively to an endurance training program. Odds are that those who most excel at marathoning would not be able to become great powerlifters no matter how hard they trained and it is not because they cannot produce enough testosterone … and the converse for great powerlifters or bodybuilders … just innately a different balance of slow and fast twitch muscle fibers likely with different concentrations of testosterone receptors as well. Heck they can even vary in how those fibers are distributed. If I had to place my marker down I’d put it on the balance of fast and slow fibers a “the critical factor.” But dang … timing of the response matter, other hormonal balances matter, nutrition matters, a host of other factors from individual genes to how the genes have been regulated and modified in the past to … more complicated than I can parse out anyway but I take comfort in knowing that most who think they can only think so because they understand so little about what is going on … they don’t know enough to appreciate how little they know.

But the op does have a GQ response: testosterone is not “used up” by muscles during exercise; resistance exercise actually increases short term testosterone levels and the more muscle mass used during the session and the greater the intensity the greater the testosterone response.

11

Thanks, but that’s not the real question, which is in what way does testosterone and/or the system that produces serve as a bottleneck to muscle growth, since there is no question it is. If it were not, then people not on roids could get as big as those on roids, which is factually not the case.

12

This isn’t a factual answer, but isn’t the limiting factor overall anabolism rather than particular muscle groups? People who do 8 week cycles of AAS might see a 20 pound muscle growth, however I don’t think that people who only work their upper bodies will see 20 pounds only in the upper body, while those who do the lower half will see 20 pounds in the lower half. There seems to be a rough upper limit on anabolism and building of new muscle.

But that could be BS also, as people with muscle memory can pack on large amounts of muscle pretty rapidly when they get back into a workout regimen. Some people claim gains of 30 lbs of LBM in a month with muscle memory.

Also the benefits of testosterone seem to level off, it isn’t like 8g a week provides much more of a gain over 800mg a week.

13

It seems a different question than what was in the op, but sure …

First kudos for stating it with some precision: "a’* bottleneck, not “the” bottleneck; and “muscle growth” not per se strength or power. Yes circulating levels of testosterone or exogenously administered testosterone like compounds can increase muscle bulk. But the same testosterone level will not have the same result in different people with different sorts of muscle fiber balances and absolute numbers of them or in the same person with different sorts of exercise or nutrition patterns or likely even at different ages. Still I am not quite getting what you are asking for now.

Are you asking for the mechanism of action? Or for what regulates testosterone levels normally? Or something else?

14

I think it’s misleading to look at things that way.
I could use similar logic to say that creatine is a bottleneck.

I think in most cases it’s more like it’s possible to be deficient in, say, testosterone in which case you will find muscle-building very difficult. And supplementing large quantities will definitely promote growth.
But inbetween that, I don’t see a reason to say that testosterone is the critical factor and a person A with X units testosterone in their blood will find it harder to build muscle than a person B with 1.2X units.

15

There are some actual studies that address that as the testosterone supplement for aging males with low normal testosterone is a high profit drug segment.

And you are right. Going from low normal to high normal with supplementation had no impact on function or strength in either the non-exercise or the progressive resistance training groups. There was a statistically significant impact on body composition over the year: after a year of progressive resistance training the group testosterone supplemented to high normal range averaged a 1.2-kg greater decrement in fat mass and a 1.7-kg greater increment in fat-free mass than those given a placebo.

Studies definitely show that older men with below normal testosterone though can increase strength with supplementation as well; the problem there has been an apparent increase in serious cardiovascular events too. Thus even use for documented low testosterone levels is now under the FDA microscope.

16

I suspect the answer is that in most circumstances, each separate muscle is limited by it’s own growth rate. The more a particular muscle fiber set hypertrophies, the slower it grows, and the higher the testosterone levels need to be in order for the individual fibers to grow any further. (that’s why growth diminishes over time and approaches an asymptote of an absolute maximum for everyone, but steroids obviously lead to larger muscles than normal people can achieve naturally)

There are relationships between the different muscle systems, of course : allegedly there are thought to be mechanisms that help to balance the relative size of muscle groups to maintain symmetry. Obviously, if you aren’t consuming enough protein, you would expect one muscle group to cannibalize another.

Still, overall, this is why the consensus among bodybuilders seems to be that the most effective known method basically is :

1.  Big compound exercises with free weights.  Usually barbell, usually squad/bench/deadlift and a few others.  Usually, the squats are done more frequently than the other exercises because the giant leg and butt muscles seem to be able to take more punishment.
2.  Take injections of testosterone totaling about 500 mg of the drug per week
3.  Consume a sufficient quantity of protein, using that whey protein powder as a supplement, of about a gram per kilogram of body mass, daily.
4.  Consume a few grams of creatine daily, and a multivitamin and some fish oil.  All the rest of the supplements are probably a waste of money.

Everyone argues about a lot of things, and there’s often very little data to support any given position, but *most *seem to agree on the above list. You can obviously skip the roids if they are illegal in your jurisdiction and/or you don’t want to risk the possible heart problems, but in terms of what is the most effective way to gain the most muscle in the least amount of time, #1-4 seems to be the consensus.

There are a lot of people who have gotten to the “monster of ripped muscles” eventually doing the above. (it obviously takes a few years) Is it the absolute fastest way possible? Probably not, but there is often no real data on whether “tip” #50031 invented to sell a muscle magazine or given by a personal trainer talking out his ass is actually more effective than not doing it.

17

Oh, one last note. #1-4 is for getting large muscles. For losing the body fat that covers them, the consensus seems to basically be :

  1. Restrict calories. Calculate your caloric need using a formula, then restrict so there’s a deficit. Plan your diet carefully and prepare all food in advance, with a scale, so that you do not eat anything other than what is on the plan.
  2. Walk a few miles daily. Running and other more “aerobic” exercises are not known to be any better.

That’s supposedly how you get to the point that you can freely rip your shirt off at the slightest excuse and feel good about it. The contest winning bodybuilder needs a far more complex plan with many supplements that may help a tiny bit, exercises targeted at specific muscles, all sorts of artificial cheats used in the days right before a competition (diuretics to remove water so you artificially have even less apparent fat, synthol injections or overtraining a muscle to swell it so it looks bigger, lotions and creams and so on, etc). None of these things help the normal person’s goal in making themselves appear sexier to average girls and getting asked all the time to help people move…