Did you know DNA affects your muscle growth?

The genetics of bodybuilding - Why a variant in the IL6 gene makes it easier to grow muscle

Before his stint as the Governor of California, and even before his Terminator days, Arnold Schwarzenegger was a bodybuilder. He was and still is, one of the biggest icons in bodybuilding, and is considered to be one of the greatest bodybuilders of all time. Yet Arnold’s 22 inch biceps and the 57 inch chest that earned him the title of ‘Mr. Olympia’ multiple times probably won’t cut it in today’s bodybuilding world, where to get even close to the top you need to be massive.

This rage to be freakishly massive doesn’t come without a cost – the recent passing of bodybuilding star Rich Piana at the age of 45 can attest to that. Piana paid the ultimate price for using performance enhancers to aid in his quest to achieve “perfection”. But, is it even possible to achieve the standard set for the perfect bodybuilding physique without the help of performance-enhancing drugs? Maybe not right now, but it’s going to be a definite possibility in the near future, and here’s why. Bodybuilding requires gaining muscle in a controlled, systematic way that involves eating right, weight training and rest, all of which are heavily influenced by genes. So, to be as muscular as one can be, all you have to do is tailor your training regime to specifically match your genes. One such gene involved in muscle growth, IL6, would make an excellent test case for whether the future of bodybuilding will be able to embrace the philosophy of staying natural.

DNA Fitness Test box

DNA Fitness Test

Muscle growth can increase the size of our muscles in two ways – by increasing the size of individual muscle cells (known as sarcoplasmic hypertrophy), or by increasing the size of muscle fibres (known as microfibrilar hypertrophy). Your choice of exercise will dictate the type of muscle growth you will experience. If you aim to lift as much weight as possible but just once like Olympic power-lifters, you will see an increase in muscle strength because of the growth in muscle fibres. Bodybuilders that perform multiple repetitions at submaximal weights increase the size of their muscle cells to build bigger muscles.

These responses to exercise are generated through a series of events that include many different proteins. Interleukin 6 (IL-6), encoded by the IL6 gene, just happens to be one of them. IL-6 is a cytokine, a messenger molecule used by cells to communicate with each other. It’s kind of a jack-of-all-trades with roles in immunity, inflammation, energy metabolism as well as muscle growth. It’s sometimes also referred to as a myokine because muscles themselves can make IL-6, but what’s even more important is that it’s absolutely essential for muscle growth.

Exercise, especially the type of repetitive submaximal exercises bodybuilders tend to use, induces the release of IL-6. However, levels of IL-6 are also genetically determined and can vary between individuals. People who inherit an altered version of the gene known as rs1800795 C have significantly lower levels of IL-6 in their blood compared to those with the rs1800795 G version, which may place them at a disadvantage in activities that require power or extra muscle strength. The frequency of the G version is higher in elite Polish power athletes (jumpers and throwers) compared to either endurance athletes or non-athletes. Inheriting two copies of the G version greatly elevates the odds of becoming a power athlete.

Additionally, IL-6 was identified as one of the nine genes that influences power status in a meta-analysis that analyzed data from 35 previously published studies. What does this have to do with bodybuilding? It tells us that staying off performance-enhancing drugs might come easy to some bodybuilders with a genetic upper hand for building muscle.

With so much at stake, it’s unrealistic to expect that staying clean by avoiding performance-enhancing drugs will become the norm for bodybuilding anytime soon. Regardless, genetic tweaking of musculature is going to take time, because strength training is only one aspect of bodybuilding, and IL-6 is one of the many genes involved in power performance. As science makes these leaps and bounds, if it reaches even a small number of people to keep them safe, that’s better than nothing at all and is well worth the money and the effort.

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