Why does it seem most lower weight class fighters get burned out by 30-32 and heavyweights can go on and be competitive into their 40's?
because lower weight guys are more active in fights moving around throwing way more punches the big guys dont use there bodies as much as the smalled guys
Because of advances in modern science and anatomy boxers will be able to fight well into their 40's maybe even 50.
Its all to do with speed. Heavyweights dont rely on speed anywhere near as much as guys fighting in the lower weight classes.