Hormones and Muscle Growth: An Overrated Correlation?
The belief in the importance of anabolic hormones is central to most athletes, coaches, and researchers. The depth of the belief extends to pretty much everything we do in the gym. For example, most people believe it's important to consume carbohydrates in a particular ratio with protein after a workout. The belief is that the right ratio maximizes the effects of insulin and insulin-like growth factor (IGF-1), some of the more potent anabolic hormones.
The trouble with this belief is that it has been challenged. When I say that, I don’t mean that there are useless fitness gurus who just want to sound controversial. I mean there are good reasons in literature to doubt the truth of one of our most foundational beliefs of exercise and diet. To use my example above, some studies have demonstrated the absorption of just as much protein without carbs as with carbs. How can that be if insulin and the golden carb-to-protein ratio is so important?
A recent review in the Journal of Strength and Conditioning is one of the best discussions on hormones and their effects on muscle growth that I’ve ever read. In the review, author Brad Schoenfeld examined the literature regarding hormones and what he calls the “hormone hypothesis.” To put it simply, when we work out the anabolic hormones come out in force, namely IGF-1, testosterone, and growth hormone. The better the workout is for hypertrophy, the higher the hormones.
However, there's a crippling problem with this theory. Even with virtually no presence of these hormones, hypertrophy still happens. Oops. Sounds like a pretty faulty hypothesis. Schoenfield's goal was to explore to what degree these hormones do improve hypertrophy, if at all. It’d be assumed that at least they would help.
The answer is divided into long-term and acute, and it is going to surprise you. Long-term results for the hormone boost we get from exercise are inconclusive. Schoenfeld indicated that an increase in satellite cell activity might boost long-term hypertrophic responses, but there simply isn’t enough evidence. Essentially it’s a guess that needs some proof.
Acutely, the answer is iffy as well, but one thing is clear. If the hormones do anything at all, it’s modest at best. Schoenfeld indicated that an 8% hypertrophic improvement would be “reasonable." He also noted an 8% increase would be an “upper estimate” of the effects of the major three anabolic hormones. Now 8% is important for a competitive bodybuilder, make no mistake, but for other athletes it’s perhaps less critical of a figure. Schoenfeld also notes that there is an increase in hormonal response with lifters over time, which is compelling.
So best case scenario here is that we need more research to elucidate the actual importance of anabolic hormones to muscle building. Regardless, for muscle building, it is very clear that these hormones aren’t as important as we think they are. The future of this research may well shift the fundamental ways we look at preparation for athletics.
1. Brad Schoenfeld, “Postexercise Hypertrophic Adaptations: A Reexamination of the Hormone Hypothesis and Its Applicability to Resistance Training Program Design,” Journal of Strength and Conditioning Research, 27(6), 2013.
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