But more often than not, the extra boxing chapter is counter-productive. He proceeded to lose sorry bouts against men who idolised him and hated to take advantage of his fast-ebbing boxing skills. Foreman, who retired at the peak of his powers after a shock loss to Ali, took more than ten years to get over his post-defeat depression. Among lighter-weight fighters, Sugar Ray Robinson, Benny Leonard and Julio Cesar Chavez all fought on past their best like Duran. The urge to do so may be strong, but the risk is still great.
Age dims the reflexes and there is nowhere for a slowing fighter to hide in the ring.
True, Ali did have success adjusting his style to rely more on resilience than speed during his 1970s renaissance. But he also took tremendous punishment, particularly at the hands of Joe Frazier in three gruelling bouts. Ali's longevity as a fighter has come at the expense of his health in retirement. His is not an isolated case. Louis is thought to have damaged his heart, fighting for peanuts at the end of his career, and died comparatively young in 1981.