Steroids don't help your stamina any. Vargas was totally gassed after the 10th round. Steroids don't help your chin. Vargas was stopped by a guy who wasn't even a big puncher at 154.
All I learned was steroids don't compensate for a massive gap in boxing skill that you are never going to close in one life time.
Vargas just had the wrong gameplan all together for that fight. The additional muscle mass to his weight cut caused his endurance issues.
Vargas never had stamina problems before that fight. His body was too muscular and tight. However, that's because they weren't utalised properly. Of course steroids can help your stamina.
Foolish thing to say, steroids can be used for more than just muscle growth and there's diferent types.