All about leverage. Look at John Molina Jr. Not a huge guy, doesn't punch all that fast, but it's like the punch detonates on your head. There's a video with Diego Corrales, who has like no muscular tissue in his body, showing how he hits so hard. Leverage and technique and intent. Some people have it naturally, some don't. Can always be improved though.
is that the golgi reflex you are referring to scrap where the body inhibits ovements to stop itself damaging ligaments, bones, tissues etc?
Norfolk, it has a part to play, Im going down the road at the moment of the involvement of the Pineal and Pituitary Glands and there connection with the Heart and Sympathetic Nervous System. Theres a routine I do thats getting C/P people walking for the 1st time. Still trying to work out the definates, interesting the technique.
http://www.facebook.com/pages/Verti-Run-The-smart-way-to-rehabilitation/229432673778169 This gives you an idea not the finished article. Gets you Fitter while repairing the injury. :good