In other words, does having higher testosterone levels within the normal physiological range (i.e. not on gear) actually result in more muscle growth?

To help us slash through the bro science, a fantastic study by Morton et al (2018) looked into why some people are ‘responders’ and some are ‘non responders’ when it comes to muscle growth and whether anabolic hormones such as testosterone have anything to say about the matter.

Over the course of a 12 week training programme, they examined whether circulating hormones, intramuscular hormones and hormone-related variables had an impact on the results of trained men (i.e. not newbies).

For the analysis, and after the programme finished, they split the group of men into ‘responders’ and’ non-responders’ based on the amount of muscle they’d packed on over the 12 weeks.

After dissecting their muscle, they found that systemic hormone concentrations are neither associated with, nor predictive of gains in muscle mass from training for both the responders and non-responders.

I.e. there were no meaningful differences in any circulating hormones measured either before or after the training programme between each group.

What they did find is that the guys who responded well to training had higher androgen receptor content within the muscle. Interestingly, the number of androgen receptors didn’t change throughout the programme for either groups….

Why is this important?

When testosterone (androgen) binds with the androgen receptor, it signals your body to build muscle. So, having high amounts of testosterone without anything to bind to is pretty useless for building muscle.

This leads the authors of the paper to conclude that the amount of muscle gained throughout a training phase is due to the androgen receptor content of the muscle as opposed to circulating hormonal levels.

So, sometimes trying to jack up anabolic hormones within the normal physiological ranges will do jack shit if your androgen receptor content is low.

The question you’re probably asking is, how can I gain more androgen receptors naturally?

Best guess, building more muscle and training heavy appears to be effective…