Frederick T. Zugibe, M.D., Ph.D., Chief Medical Examiner in Rockland County, N.Y. and Adjunct Associate Professor of Pathology Columbia University College of Physician’s and Surgeons, N.Y. "crucified" both fresh cadavers (or body parts) and living students (using only straps) to test and study the practice of crucifixion.
Zugibe found that his students "crucified" (with straps) in [the traditional Christian] manner began having serious difficulties almost immediately. When they lurched forward, as in Zugibe’s lab photo
[at link], their chests, shoulders, and arms began cramping in ten to twenty minutes. Only his strongest student was able to stand it for forty-five minutes. Death would come quickly crucified like this, if you didn’t pull free and fall off first! That’s the problem. Roman records indicate that people survived for days on the cross. These victims must have been in a different position, a more comfortable position (relatively speaking), in order to survive that long.
The peg (or seat) solves a lot of logistical problems. Sitting on the peg makes you more comfortable, so you will suffer longer. That was, after all, the point of crucifixion: prolong death so as to suffer for as long as possible. Roman records refer to a man who was taken off the cross after three days and recuperated. Another man lasted a full week before he died—seven days alive and suffering on the cross. Using a peg for the victim to sit on would make these scenarios possible. And another thing: sitting on a peg would prevent you from lurching forward.
[I did my own simple experiments and concluded a horizontal restraint was also required - hence the cornu.] The seat would enable you to rest your weight on it, killing gravity’s pull forward away from the cross.
http://bertgary.blogspot.com/2009/01/wa ... wn-in.html