Originally Posted by pugilist_boyd
the rock # 1 but i never seen hagler tire in the few bouts i seen him in did he ?
Yes, in his first attempt to win the MW Title, Marv did tire late in a 15 round draw against a good candidate for this distinction, Vito Antuofermo. Vito ran five miles a day, even when not training for a match.
Sometimes, there's no correlation between conditioning and endurance, and the classic example of this is Earnie Shavers. While a contender, Earnie was actually the best conditioned heavyweight in boxing, but the weight of his arms, the force he put into his haymakers, and his complete inability to pace himself always made him notorious for running out of gas quickly. Nothing he did could have improved his performance in that regard, although he tried to cultivate his staying power diligently.
SRL maintained top physical conditioning. Jeffries was a freak in that respect. Sweet Saoul Mamby sustained an incredibly long career with his dedication to skipping rope and disciplined training. Emile Griffith was no slouch in that regard either.
Over the last 30 years, it's hard for me to go against Vito. In back-to-back-to-back 15 rounders, he tired out veterans Hugo Corro (RIP), Hagler and Alan Minter (another noted strong endurance performer). Vito could be stopped on cuts, but good luck wearing him out.
Sal Sanchez wore down and stopped Danny Lopez late twice. Little Red was known for his staying power as well as his punch.
I'm omitting Aaron Pryor and Henry Armstrong on purpose. They were both physiological freaks of nature who possessed extreme endurance as an accident of birth. (At Armstrong's autopsy, it was found that his heart was larger than usual, and he had an abnormally slow heart rate by nature. I suspect the same quirk applies to his friend Pryor.)