Is your IL-6 activity enhancing or limiting your muscle growth?

Alex Auld


February 14, 2023

A common misconception is that resistance training directly leads to an increase in muscle mass and strength. In fact, rather than building it, resistance training breaks down muscle, but in doing so creates the necessary metabolic conditions for muscle repair and growth to occur. This is known as a training adaptation.

One process that is central to the growth of new muscle is the activation of satellite cells. When activated, these specialised cells multiply in number and fuse with muscle fibres, increasing overall muscle size and strength.

A molecule that is key to the activation of satellite cells, and therefore to muscle growth, is interleukin-6 (IL-6). In addition to stimulating satellite cells post-exercise to repair, remodel, and develop muscle tissue, IL-6 also suppresses inflammation, further optimising the conditions required for muscle growth.

However, beyond this acute response to resistance training, IL-6 can also have a negative impact on inflammation levels and overall health. High resting levels of IL-6 caused through secretion of the molecule by fat tissue, immune cells, and blood-vessel walls can result in chronic, low-grade inflammation.

In addition to causing tissue damage that can lead to conditions such as type II diabetes and cardiovascular disease, chronic inflammation can cause the breakdown of existing muscle tissue and limit potential growth.

Calculating your Inflammation and Muscle Growth result

In creating the Inflammation and Muscle Growth report, the FitnessGenes science team combined genetic variants that influence both the activity of IL-6 and the function of IL-6 receptors with relevant lifestyle risk factors (such as age, physical activity, and diabetes risk) to predict the effect that IL-6 is having on muscle growth.

Based on the combination of these influential genetic and lifestyle factors, seven possible results were created, between which all FitnessGenes members were categorised:

1. Enhanced muscle growth

2. Mildly enhanced muscle growth

3. Average muscle growth

4. Mildly impaired muscle growth

5. Impaired muscle growth

6. Moderately impaired muscle growth

7. Severely impaired muscle growth

As you can see from the graph above, IL-6 is positively impacting the muscle growth of 45% of FitnessGenes members. For these members, ensuring that they optimise their workouts and nutrition through their recommended actions will help them to maximise their genetic muscle building advantage.

At the other end of the scale, 28% of members may have IL-6 activity that is negatively impacting their muscle growth and increasing their risk of chronic inflammation. This may be due to the genetic variants that they carry, their current lifestyle, or for those at the greatest risk, a combination of the two. For these members, fundamental changes to their lifestyle and exercise may need to be introduced to manage their risk of muscle breakdown and improve growth.

Inflammation and Muscle Building recommendations

So, what can those at the greatest risk of reduced muscle growth and chronic inflammation do to address this issue? While each result group has their own set of personalised recommendations, we’ve selected a handful from the highest risk group; severely impaired muscle growth.

1. Include two days of resistance training with regular aerobic activity each week.

Combining resistance exercises with aerobic activities, such as walking or cycling, will help you maintain healthy IL-6 levels and optimise your ability to increase and retain muscle strength.

2. Add 15 minutes of vibration therapy 3 times a week into your recovery.

Vibration therapy has been shown to both increase the clearance and reduce the production of IL-6, which may help with building strength in older populations.

3. Ensure that you are getting enough zinc in your diet (11 mg for men and 8 mg for women per day) through foods such as shellfish, seeds, and legumes.

Zinc deficiency can increase resting IL-6 levels, so make sure you are consuming enough of this mineral to prevent chronic inflammation and aid muscle building.

Understand your personal Inflammation and Muscle Growth risk

If you’re a full FitnessGenes member, your report is now live in the Members’ Area. Login to view your personal result, insights, and actions. Not yet a member? Get started completely free of charge by unlocking your lifestyle-based reports with three simple steps. Follow to link in the top menu to create your free FitnessGenes member account.

Alex Auld

One of FitnessGenes' first full-time employees, Alex re-joined the company in 2021 after completing his MA in Global Communications at the University of London. He now oversees all customer communications, helping to ensure that our members get the most from their results. An amateur triathlete, you can expect to find him in the pool, on the bike, or running laps of his local park most weekends.

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