His doctor, who works for the UFC, recommended Jackson to an age specialist who recommended the therapy.
It was hard for me to train, it takes time to heal, I couldn't do certain things, but this was my first time ever using testosterone. I took what the doctor prescribed to me and I went to the pharmacy… I gave myself small doses and that shit immediately changed me, that's why I am saying now I am not going to retire. I am not gonna retire no time soon, its just unfortunate that I got this injury.
I started hitting it up pretty good, I still gotta take care of my knee but I feel like a 25 year old again.
He also talked about how the testosterone improved his sex life, but you'll have to go read the Fighter's Only interview to catch up on Jackson's bedroom prowess. Jackson said he was skeptical of the testosterone replacement therapy in the past, but changed his mind when he learned more about it.
Jackson claims the testosterone helped him heal from injuries faster, but that is exactly what performance-enhancing drugs are often used to do. Thiago Silva was suspended for one-year after using a banned substance before his fight with Brandon Vera. He said afterwards he used because he needed a win after a back injury.
Dan Henderson and Chael Sonnen are both users. Nate Marquardt was cut from the UFC when his high testosterone levels knocked him out of a bout hours before weigh-in.
Michael Bisping, a UFC middleweight and Jackson's friend and onetime training partner, spoke out against the practice in August. He blasted testosterone users on Twitter, calling them "steroid users" and cheats.