The kickback depends on how the blade/chain meets the surface. When
saw chain on the long part of the bar pinches, you may get a healthy
pushback. However, when plunge cutting, if the nose of the bar
contacts the surface, the whole bar will swing up rapidly since the
chain moves DOWN at that point. One of the reasons plunge cutting is
so hazardous.

For circular saws, the problem is that they are already close to your
legs and hands. They don't have to go far to bite you. Carpenters do
remove or pin back the guard, leaving the blade in the air with the
saw upside down. Most saws don't have a blade brake, so they are still
spinning after the trigger is released.
Do NOT cut a board laid across your knee. More than the board might
get cut.

Tom

On Fri, 6 Feb 2009 14:42:56 -0800 (PST), wrote:

Fortunately I have not experienced circular saw kickback or chain
saw. I have read about it and I am wondering how strong it is,
though. I know the answer probably depends on the HP of the saw, the
material being cut, user posture and strength, etc. Is the force
imparted so strong that a reasonably healthy guy would still be able
to hold onto the saw (with two hands) or does the saw simply go flying
out of your hands?

Thanks,
Tim