"Wouldn't that be consistent with Travyon Martin getting off of George Zimmerman and George Zimmerman raising the gun and firing it?" Guy asked Root, a use-of-force expert.
"It could be consistent with any kind of movement ... We weren't there so the info that we have is George Zimmerman's statement," he said.
Later, defense attorney Mark O'Mara straddled the dummy himself, pounding the back of its head against the carpeted courtroom floor, demonstrating how he says Martin gave Zimmerman the head wounds seen in police photographs from the night of the shooting.
He later asked Root -- a former police officer with extensive training in firearms and self-defense -- if it would have been possible for Zimmerman to reach around Martin's body to get at a gun located near his hip.
"Yes, sir," Root replied, minutes before Nelson called a lunch break.
Earlier, Root testified the apparent fight between Zimmerman and Martin went on for a relatively long time -- some 40 seconds -- and was clearly marked by a high level of fear and anxiety.
"I have personally sat there and timed it myself, where it is about 40 seconds of time. That's a very long time to be involved in any type of physical altercation," Root said.
"We have a golden rule," he told defense attorney Mark O'Mara. "If you have not successfully completed the fight, if you have not won the fight in 30 seconds, change tactics, because the tactics you are using are not working."