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Mythbusters! The Growth Hormone Myth

By August 17, 2010December 27th, 2013Guest Blogs

The Growth Hormone Hypertrophy Myth
By Mark Young

The common assertion in strength training literature (I use that term loosely) is that compound movements must be done (and short rest intervals used) to maximize the growth hormone output associated with training to accentuate muscle hypertrophy.

In simpler terms:

Big compound movements + Growth hormone release = Hyooge muscles (i.e., looking like Bret Contreras)

(editors note: Compliments go a long way in these parts!)

For years studies have demonstrated that training using compound movements and/or short rest intervals does indeed increase the output of anabolic hormones giving strength to this theory which would normally be considered a good thing. Sounds good right?

However, more recent research has demonstrated that although testosterone, growth hormone, and IGF1 do rise with when training the larger muscle groups, there is no difference in muscle protein synthesis (muscle building) or intracellular signaling when compared to a group training without these hormonal changes.

Of course, caution is always warranted when we’re looking at mechanistic studies where hypertrophy is not actually measured (as this is how we got in this mess in the first place) so a follow-up training study was conducted to demonstrate the effects of training in the presence or absence of these hormones on hypertrophy and strength.

In this study, 12 males trained their biceps using a unilateral arm curl for 15 weeks. However, one arm was trained on one day strictly performing curls (Low Hormone Group). The other arm was trained on a completely different day followed immediately by several leg exercises aimed at increasing hormone concentrations in the blood (High Hormone Group).

From weeks 1-6 each arm was trained once per week. From weeks 7-15 each arm was trained two times per week although 48 hours was always left after the arm only condition (Low Hormone Group) to make sure that they did not experience any influence of the additional anabolic hormones while still while their protein synthesis was still elevated from training the previous day.

For those who are interested, each arm workout consisted of 3-4 sets of 8-12 reps using 95% of their bicep curl 1 rep max. In addition, the high hormone group performed 5 sets of 10 reps of leg presses followed by 3 sets of 12 reps of a leg extension/leg curl superset after each arm workout.

At the end of each workout the subjects drank a beverage containing 18 grams of whey protein to facilitate maximal protein synthesis. Isometric strength, 1 repetition max, and 10 repetition max for the bicep curl were taken pre-training and at 15 weeks. MRI and muscle fiber biopsies were used to determine increases in muscle growth.

As it turns out, the high hormone condition did elicit greater responses in testosterone, growth hormone, and IGF1 than the low hormone condition. While both groups experiences increases in strength, fiber hypertrophy, and muscle cross sectional area, there were ABSOLUTELY NO SIGNIFICANT DIFFERENCES BETWEEN THE TWO GROUPS. In other words, training in the presence or absence of endogenous hormones didn’t make a lick of difference.

Criticisms of this study might include the fact that the subjects were novice lifters, that they didn’t have enough protein after training and that there were no dietary controls.

To these I offer a two considerations.

1 – Novice trainees will indeed make gains in response to almost anything. It is certainly harder to make gains with advanced lifters. For this reason I would argue that the differences would be LESS pronounced in people who were already trained since their gains are already limited.

2 – Whether or not the protein intake was actually sufficient (which THIS STUDY indicates that it is) or whether the diets were controlled doesn’t really matter because the study was a within subject design. In other words, because the study was comparing one arm to another instead of comparing between two separate groups means that each arm was subject to the same nutritional effects as the other arm since the belong to the same person. This minimizes the possible variability usually found in a between subject design (i.e., one group ate a lot of protein and calories and the other didn’t) and makes a within subject design more powerful. If there was a difference between methods, this type of design would have been the best suited to discover it.

All in all, the big picture is that training the larger muscle groups and shortening the rest intervals DOES increase the output of anabolic hormones. However, these hormones do NOT cause any additional hypertrophy.

That is not to say that you shouldn’t use the “big bang” exercises or that short rest intervals are useless. Heavy lifting taxes more muscle groups thereby increasing your chances of strength and growth. Short rests also make workouts quicker and more efficient (or possibly allow more training volume during a fixed amount of time).

It does mean though that you don’t HAVE to do the big exercises or maintain short rest intervals to elicit hypertrophy. For those who find it difficult to squat, deadlift, or bench due to an injury or condition, this should come as a welcome change to the usual “do the big 3 or be forever small” mantra. You have to load the muscles and you have to feed your body, but how you do it is up to you.

In the end, the anabolic hormone cascade is not going to do you any favors in terms of extra hypertrophy…because that is straight up bro science.

Consider That Myth Busted!

For those who want to reach Mark to bitch him out for shattering their dreams of becoming muscular and sexy as a result of endogenous hormone release you can visit his website at


  • Ian Mills says:

    So, if the elevated levels of “strength” building hormones did not in fact result in elevated strength and mass then what is the point of people supplementing with them in the MLB showing obvious signs of mass and strength gains. I am under WADA rule so there is no experimenting here.

    Does this mean that elevated HGH does not speed up recovery or elevated levels of Testoreone not give you that extra oomph to work harder? Maybe the smaller muscle groups dont actually benefit from elevated levels where the big muscle groups do? That would be nice to know.

    This is intriguing.

    If you guys mythbust the study that was done on doing sprints after a heavy workout to boost HGH levels then I would be forever grateful. The only thing that gets me through those 4x200m strides after being destroyed already is the confidence that its actually speeding up my recovery by boosting my natural HGH secretions by as much as 400%.

    Mad Dawg Mills

    • Matt P says:

      You can inject a lot more hormone than your body could ever produce naturally.

      Putting a supraphysiological dose into your body is not even remotely the same thing as the natural pulses of hormones that occur in your body.

      • Ian Mills says:


        I understand that… but if a huge dose helps then wouldn’t it make sense that a relatively smaller dose help as well? The study mentioned by Mark shows that it obviously doesnt but my biggest question is this: is there something else going on that isnt being addressed and that the final conclusion isnt necessarily final?

    • Ian, do you have a link to the abstract…on Pubmed for example? My guess is that the research is accurate but how much it helps recovery probably hasn’t been studied.

      • Ian says:

        I will try and track it down. I read it a while back and didnt care at the time to take note of the study or who did it.

      • Ian says:

        As you mentioned Bret, the benefits of higher levels of HGH on recovery is not addressed, however it was my impression that HGH aided in recovery; is this not the case?

        Or, did I understand Matt correctly, while HGH may act in correlation to strength gains by speeding up recovery, they are not the direct cause of strength gains.

  • Matt P says:

    One more from Stu Phillips to round it out:

    The hormonal hypothesis has never made much sense to me and I’m glad people are starting to realize that it’s a pretty weak concept.

    Even researchers have gone out of their way to promote it for reasons unknown. Look at this one:

    Conclusion says “The correlations between T and the changes in isometric strength and in muscle CSA suggest that both serum basal testosterone concentrations and training-induced changes in acute testosterone responses may be important factors for strength development and muscle hypertrophy.”

    Except look at what happens to the strength athlete (SA) group: “Significant increases of 20.9% in maximal force and of 5.6% in muscle CSA in NA during the 21-week strength training period were greater than those of 3.9% and -1.8% in SA, respectively.”

    Moderate strength gains and loss of size in trained strength athletes trying to maximize hormonal responses. But they conclude that it’s the hormones creating the positive effects anyway.


    • Ian Mills says:

      The second study you referenced (I only read the abstract cause Im cheap lol) was still only done with leg extensions. I should have specified that the increased hormone levels may be beneficial when lifting multiples of your own body weight (Squats, dead lifts, hip thrusts etc.) Doing leg extensions does not satisfy my query.

      If they Mythbust using heavy lifts then I will surrender to the conclusions because I dont need to get “jacked” to do bicep curls or leg extensions but I do need to get my hormones pumping when I am staring down twice my bodyweight….now thats a potential topic of study: Does Pounding ones chest, stomping the floor, grunting or mentally picturing a grizzly increase the secretion of Testorone, adrenaline or other potential performance enhancing hormones…lol

      Its just my experience but I have gotten much stronger without increasing CSA because of my nutritional plan so I don’t find the reduction in CSA a concern from my point of view. I train to increase my Power to Weight ratio and not to look good in a tight T-shirt.

      Kind Regards,

      Mad Dawg

      • Matt P says:

        Ian, I’m not sure why you’re focusing on the details of the protocol. That’s really the least important point there. I posted that to demonstrate that researchers have tended to promote hormone spikes as the causative effect of training when even their own results indicate the contrary. So, yeah. Not sure where you were going with that.

        As far as using compounds, Mark laid out why in the post: because they tend to work lots of muscle at once. This isn’t saying you shouldn’t use compound exercises, because there’s more reasons than “magic hormone spike” to do compound movements. They haven’t suddenly lost effectiveness because bad science was removed from the equation.

      • Daniel says:

        Heavy compound movements work the biceps indirectly, therefore it would interfere with the results of the study.

    • Awesome stuff Matt! Thanks!

  • Dave Sandel says:

    Can someone forward this to Ferruggia and his circle of trainers?

    • Dave, let’s be fair. Recommending big, basic compound lifts could never do nobody no harm, right? They obviously work, just not through increased test and hGH levels. Maybe there’s another physiological mechanism at play. Maybe it’s just due to the fact that they hammer the erector spinae…the secret to total body strength and foundational strength.

      • Dave Sandel says:

        I agree 100%, and that has always been my counter to anyone that still believes it’s the hormonal response. However, he, as one of the more well-known guys in the industry will specifically state that is because of increased T and HGH. I don’t like when our “leaders” perpetuate misinformation and bro-science. That’s all.

    • TJ says:

      I’m pretty sure Jason isn’t using the big compound lifts for their GH responses.. I’m pretty sure it has more to do with training economy.

  • Matt P says:

    Ian, you appear to be operating on the juicehead assumption: hormone fluctuations matter because some guy can run a gram of test and blow up.

    For comparison: most average test cycles will run say 500-750mg per week. Blood levels will stabilize a little higher than that using the long esters that most run.

    In comparison, the range of 300-1000ng/dl that’s considered “normal healthy range” in an adult male? That translates to about 70mg per week, and even with those normal daily fluctuations around a workout, test will never go outside that boundary.

    The effect has been mistaken for the cause. Hormones indicate a stress imposed on the system. Science repeatedly demonstrates that the desired effects – strength and lean tissue gain — can occur without that cause, which means that the cause is superfluous.

    If you really want me to give you a biochemistry lecture on why this can happen, I’m happy, but I hope you like acronyms.

    Correlation is not causation, and such. Happening along with the things that stimulate growth does not mean that they cause growth.

    • Dave Sandel says:

      Matt P,

      You sure sound like a guy that writes for an extremely informational fitness blog out of New Zealand. Same first name and last name initial. Peculiar…. ; )

  • Ian Mills says:


    I would love a lecture in biochemistry, specifically in the best natural way to restore levels of glycogen in the muscle fibres (Maple Syrup, Honey) without causing too much of a candida response.

    I was just talking to my buddy who is a Doctor fresh out of Medical School that I need to find a friendly neighbourhood biochemist who can teach me something (for free of course, hence the friendly neighbourhood bit). Do you have a website or a blog or were you just being facetious? 🙂

    I appreciate you clearing up my confusion

    Thank you

  • Ian Mills says:

    Found your site Matt…isnt the internet great? If I have any more questions after I read through your stuff, I will let you know bud

  • Bruce Kelly says:

    To me there are issues with the study because they didn’t use what I would consider compound movements (leg extensions, please!). I understand the confounding impact those exercises may have on arm hypertrophy which just gets back to the flaws in the study. Furthermore, if we all agree compound exercises are necessary for overall strength and at some point cross sectional muscle size is the limiting factor in further strength gains, then there seems to be a conundrum here.
    While this type of research is interesting and thought provoking ,as with most research, it is not real world (at least not my real world), it done by academics not people actually training people, and, to me anyway, has little or no application.

    • Matt P says:

      Bruce, I’m not sure you understand the role of Occam’s razor and the preponderance of evidence in making claims like this post.

      The idea of hormone spikes causing training effects is inelegant and does not mesh with what we know of muscular responses to resistance exercise. It’s entirely unnecessary in understanding the responses to strength training.

      That you can point to methodological flaws in a few studies because they “might not” line up with a fundamentally bad idea that you happen to prefer is akin to taking a puzzle of a cat, taking out a single piece, and then saying it might be a dog. The big picture doesn’t vanish because a few details are out of order.

      There is no conceivable mechanism by which squats would magically have a greater impact on local growth elements than a leg extension, and even so the fact that the exact protocol isn’t identical is irrelevant: hypertrophy signaling is activated even without the big hormone spike. That’s the important part.

  • Johan says:

    Could the GH release still be of use for fat burning though?

  • David Ratcliffe says:

    Great guest blog! Keep up the terrific work Mark.

  • Anthony says:

    Great Read

  • Dush says:

    I’ve always maintained longer rest periods between compound lifts, I figure that you’re not training intense cardio you want to train strength (well that’s my goal when I do compounds) so I need to give my cardio-v system a chance to recover. Otherwise you’re simply unable to maintain maximum power output.

    In between isos though I hardly take any rest, as they don’t feel like I’m doing much.

  • Tim says:

    I agree with the point of the article, but my only concern is the study. Has anyone ever tried just making one arm grow and not the other? I feel like it’s highly unlikely for the body to grow that unilaterally. I’m not sure if there’s some way for your body to control that or if it really is based on the work the individual muscle does, but it seems unlikely to grow one arm significantly without the other even if you were trying. Might be wrong but that flaw popped into my head.

    A better study would utilize two separate groups of people and control diet. I’d like to see that.

  • TJ says:

    I think the primary problem with the study is its length.. At first glance, 15 weeks seems like a long study.. However, if you consider an average steroid cycle is around 8 weeks (and total concentration of test in the blood is MUCH MUCH higher than the response from training), then it’s really not surprising that they didn’t find any difference.

    Plus the bicep muscle is such a small muscle, that differences in strength, CSA, and hypertrophy would have to be extremely significant to find a difference.

    Having said that, I completely agree with Mark. Does anyone really still think compound movements primary mechanism for increased hypertrophy is their hormonal response?

  • First off, great stuff Mark. I first saw this presented by Dr. Phillips (who you know very well) at ACSM in 2009 and wrote about it on my blog at

    Great minds thinks alike–awesome! Great to see more science in the strength world.

    As Mark pointed out, test increased, BUT when in a NORMAL range did not enhance muscle hypertrophy.

    Almost everything in physiology is NONlinear. If you are very low in test, adding more helps a ton.

    If you are in the normalish range, not so much.

    If you inject superaphysiologic doses, yes it helps (as pointed out).

    There is literature to support the notion that it is LOCAL growth factors most likely that help. Make perfect sense=more local stress on the muscle would need more repair.

    Compound movements work due to more overload and stress on more tissue. Keep in mind that they were looking at more “global” hormones.

    For maximal glycogen replacement (assuming you are doing 2 a days and NEED it to be replaced ASAP) look into Vitargo.

    If you are not doing very intense training back to back, most of the time glycogen levels will be normal or very normal within 24 hours as long as calories are sufficient.

    Rock on
    Mike T Nelson PhD(c)

    • Ian Mills says:

      Thanks for clarifying Mike. My two a days involve a weight session or hill or sprint session followed by a push session in the ice house or doing 5 runs at the track (skeleton) once the season starts in the winter so quick replacement is key for me because the G-force stress adds to the crash at the end of the day.

      In the offseason, I only do one 2/day every week but once the season starts it becomes more like 3-4/week on a good week. It may or may not be vice versa depending on when we slide during the day.

      However, I do not consume products with artificial sweetners for any reason which is why I was referring to natural replacement (Maple Syrup, Honey etc.).

      Mad Dawg Mills

  • Bruce Kelly says:

    Matt P,
    You may have a point but I’ve been in the field for over 25 yrs. and have trained 1000’s of athletes/clients. I’m wagering that is not the case with you.
    Though hypertrophy is part of the training mix there are other reasons compound exercises should be the foundation of strength training protocols like efficient use of training time, intra/intermuscular coordination and recruitment patterns, power development if done correctly, etc.
    If you want localized hypertrophy, which is what this study seems to be about, then go for it.
    I don’t train bodybuilders so I don’t see the application for my athletes and clients.

    • Matt P says:

      You really just pulled out the “I lift a lot of weights so I know more about science” line on me? Of all people? Good lord at the meta-humor.

      In any case, you aren’t even responding to what’s been said, you’re just arguing to argue. Whether you didn’t bother to read or you’re just trolling, I don’t know.

      Nobody is disagreeing with the practices, only the scientific underpinnings of the suggestions (i.e., training adaptations have nothing to do with acute hormonal responses). How you get the idea that you shouldn’t do compound exercises, when it’s been flat-out said you should, or that compound exercises don’t have other effects, is beyond me.

      But leave it to the internet to start people arguing for the sake of arguing.

  • Chad says:

    What about the body’s natural tendency to want to grow symmetrically? I recall Kelly Starrett explaining that, for example, if your right leg was broken, you could do one leg exercises with the left leg, and it would actually carry over to stimulate the right leg. I suspect there is a similar mechanism going on here which would pretty much negate the whole study. Also, consider that the increase in hormones often lasts more than just one day. Squat heavy on Monday and get your testosterone serum level taken on Friday, it will be elevated. So, even if they were only doing full body movements once a week, the hormonal “wave” would have had longer lasting effects than just post workout that day.

    • Matt P says:

      The cross-talk effect is neurological, not hormonal.

      As far as constant elevation, do you have a peer-reviewed source for that? Because as far as I’ve ever seen, the workout spike is transient, not chronic.

  • Cliff Keutel says:

    I liken this to the claims that it is GH responsible for increased fat mobilization and oxidation during lactate training when, at least in the immediate sense, it is catecholamines responsible for the effects being seen, with any relative impact from GH happening later on. The training itself still has an effect and plenty of value, just not necessarily for the reason/mechanism that often gets the credit. So in terms of practical application, there isn’t a massive shift, per se, it’s just a matter of our understanding about why what is or isn’t happening is the case.

  • Omar says:


    What is the reason the body increases the output of anabolic hormones when shortening rest intervals? It doesn’t increase hypertrophy so what is the purpose? Great blogpost as ever.


  • anoop says:

    GH release is because of metabolic accumulation in the muscle. GH secretion is highly correlated with lactic acid accumulation. Any activity that stress the metabolic pathways like hyperventilation, breath holding, hypoxia and even nicotinic acid ingestion have been shown to profoundly influence growth hormone release. Those activities are no way anabolic.

    Not sure why there is testosterone increase though. Even though there is, it is too transient.

  • Rich says:

    Isn’t there a GH response to hunger as well?

  • PolyisTCOandbanned says:

    I knew some guys with huge upper bodies as gymnasts, that never did a lower body lift in their lives. I’ve seen guys in wheelchairs with huge upper bodies as well.

    I know it’s awfully simple, but I suspect muscles grow because of the stress put on the muscle itself. Not from squatting hormones, not from compound versus isolation, not from free versus machine. But just from stress.

  • Garett says:

    Totally lame and worthless study. Only idiots would defend this as useable exercise science.
    1) Low production exercises, leg presses and knee wrecking leg extensions to measure hormone changes. If they had any common sense, have them do real squats with a heavy freeweight barbell. Won’t interfere with biceps stimulation.
    Very small amount of sets and reps. Not enough to qualify as a warmup. No one in the real world of serious training does that. A real workout has far more sets and those training for serious results aim to do it with low reps and heavy weight.
    2) Only done twice a week. Any serious weight training program is at least 3 times per week, usually more.
    3) Tiny amount of negligible protein. 18 grams supplemental only once? Most serious trainers consume several times more than this at and in between meals.
    4) Two groups of only 6 people each. Statistically insignificant.
    5) Very short period of time. Only done for 15 weeks.
    6) No measure of sleep or other activities. Those doing serious training often sleep up to ten hours a day.

    Check the hormone levels of people doing real training, use enough people from a cross section of young, old, trained, untrained, etc. Have them on various amounts of food and supplement intakes. Show the effects of rest, sleep, other activities. Be assured of getting far different results.

    This study belongs in the garbage and is irrelevant to the real world. Obviously those arguing in favour of this nonsense may be intellectual. They have a piece of paper saying they have this or that degree. BSc = Bullshit, MSc = More of the Same Bullshit, PhD = Bullshit piled high and deep. Just one other case of where it has removed them from the real world, their weak frail bodies residing in Ivory Towers of impractical and incomplete theories.

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