Which type generates more power?

[Mares]

how to develop fast twitch muscle then? does weight lifting improve it?

[Richie-G]

its genetically determined, you are born with a certain amount of fast twitch fibres and slow twitch ones, hence why we have sprinters and marathon runners.

You can train them to a certain extent, in that you can become more explosive using plyometrics and explosive forms of weigthlifting.

[RightCross94]

Shorter stockier types with thick legs and torso's are generally able to get more leverage into punches like hooks and uppercuts (case in point: Mike Tyson)

Long, tall types with long arms are able to get more leverage into the long straight punches (Tommy Hearns)

[vietsouthpaw]

Having broad shoulders or longer arm length?

well i think the power of the punch is the snap and weight distribution from your legs....but i agree with right cross if anything having broad shoulders helps more than having longer arms