Androgen Receptors

Every hormone in the body has a specific type of receptor that it binds with. You can think of the receptors as keyholes with the hormones being the keys. When the hormone floats through the bloodstream and reaches the muscle cells it fits into the receptor and unlocks a specific set of activities the cells are designed to be able to perform.

In the case of building muscle, the androgen receptors are activated by androgenic hormones like testosterone and DHT. The male physique relies on the concentration of androgen receptors in various muscle groups. Hence the name of the program "Androgen Density". The researcher found that androgen receptors concentration in men is higher in the upper body than in the lower body.

Specifically, the muscles of the upper chest, shoulders, upper back, neck have a higher androgen receptor concentration than the muscles of the lower body. This means for men who are trying to achieve the androgen dense physique, is that changes in anabolic hormones like testosterone levels will cause a relatively large change in the muscles of the upper body.

When men perform resistance training workouts, the effects are more noticeable in the upper body. Men's bodies are designed for increased levels of muscle mass in the upper body. If it comes to the lower body, I noticed and seen legs being more designed for power and speed.