Originally Posted by Boilermaker
I think it has a lot to do with the emphasis on running in training. Look at the Chris Byrd vs Shane George fight to see how some of the modern heavyweights would look if they trained the way the earlier fighters did. Whether this is an advantage or not, i guess the jury is still out, as Byrd never went too well in that fight (although age might have also been a factor).
Bingo. Running can kill your size. What I mean but that is some of the muscle density. We're not talking 3-5 miles but the 5-15 miles daily types with fewer and bigger concentrated meals, rather than many more smaller sized meals & nutritional benefits most athletes get today.
Byrd failed because he dropped too much weight from his stabilized fighting days. You can't just trim yourself down like that without hurting your resistance or stamina.
I think this is a particular reason why many boxers had smaller thigh measurements back in the day. They had strong, very conditioned legs. But their legs were for the long haul of a fight, and not quite as big as some fighters legs are nowadays. Longer distance running can do that to you. But then now that I think about it there are many boxers that appear rather top-tall, especially some of the HWs. This may be more because of a dismissal of leg-based conditioning (Interval training or distance) in favor of alternatives like swimming. I'm not sure. Genetics plays a part, naturally.