Are there any actual studies to back up the claim that testosterone levels decline with age? I have read studies that testosterone levels have been declining over time, that is, men in the 1950s had more testosterone than men today, but I do not recall seeing a study showing age related decline.
Is there such a study?
The male Endocrine system up-regulates until age 25 or so then levels out and after age 30 declines 1-3% per year. Of course everyone is different and genetics play a part in how much you lose. Some guys don't lose much at all.


