i train a guy who is 57 and had a liver transplantation 15 months ago after absuing alcohol and hard drugs for over 40 years. he got meds who made his breast grow to counterbalance some hormonal stuff going on after the transplantation. he also got brain damage from liver failure and can't move the weights in a good rom. however, within a year of progressive weight training and a almost healthy diet he could build significant muscle, especially to his arms because he is a curl addict.
i don't believe in all this low testosterone gossip. just lift good, stick to the routine and don't embrace excuses. if this guy can build muscle and strength, everybody can.