I wish that I had found this site before. A couple of years ago I noticed that my erections were not as good as they had been when younger (I am 57). My erect length was 1/2 inch shorter than when measured in my 20s. In order to try and regain this length I purchased a penis extender which did the trick. Not only did I regain the loss but the girth improved considerably as did my ability to maintain an erection.
I have decided to try exercises without equipment for a period to see what effect this has. I am quite happy with things now but an experiment would be interesting . I will post full statistics later but currently erect length is 8.3 inches and girth is 6.4.