Man, Kimble was a very lousy fighter
he got his ass kicked everytime he tried to fight.
I believe in me. I'm a little screwed up but I'm beautiful.
Dr. Nichols is big and stocky and could easily throw a scrawny little guy like Dr. Kimbal around the room. But Dr. Nichols has superhuman powers; hit him in the privates and he can shake it off in about 5 seconds, not that I would know about those things.
Obviously toward the end Dr. Kimbal was on pure adrenaline and was gonna let him have it, consequences be damned. I would too.