Superhuman? No, Just Very Frightened

The AP just reported a story that vividly illustrates the incredible capacity of the human brain and body to perform under intense pressure. A Kansas man named Nick Harris was driving his 8-year-old daughter to school last week when he saw a car back up and run over a neighbor’s 6-year-old daughter.  “I didn’t even think. I ran over there as fast as I could, grabbed the rear end of the car and lifted and pushed as hard as I could to get the tire off the child,” Harris said.

The story continues:

He realized the little girl was Ashlyn, a friend of his daughter’s. Harris carried the screaming first-grader to the sidewalk and was going to get his phone to call 911, but Ashlyn said she wanted him to stay with her. He told people nearby to get the child’s mother, who lives a block away. There were no witnesses to confirm what happened. But Ottawa police Lt. Adam Weingartner said, “I don’t have anything to dispute it.”

Hough said Ashlyn told her Harris lifted the car off her, Weingartner said. Weingartner, the first officer at the scene, said Harris “was amped up pretty good. The first words out of his mouth were, ‘I lifted the car off the girl.'” He said it appeared Ashlyn wasn’t pinned under the car long enough to be seriously hurt, Weingartner said. Hough said her daughter was released from the hospital that afternoon with a concussion and some scrapes.

It’s an amazing story, if not totally watertight: there were no witnesses, and what happened to the car that ran the girl over? But Harris’ feat, while incredible, is not impossible. Chapter Two of Extreme Fear begins with the story of a similar episode, in which a Tucson man ran to lift a car off a bicyclist trapped underneath.

Because most of us rarely find ourselves in life-or-death situations, it can be hard to appreciate what a powerful effect fear can have on our physical speed and strength. Under acute stress, the sympathetic nervous system prepares the body for sustained, vigorous action. As the adrenal gland dumps cortisol and adrenaline into the blood stream, blood pressure surges and the heart races, delivering oxygen and energy to the muscles. It’s the biological equivalent of opening the throttle.

Vladimir Zatsiorsky, a professor of kinesiology at Penn State who has extensively studied the biomechanics of weightlifting, draws the distinction between the force that our muscles are able to theoretically apply, which he calls “absolute strength,” and the maximum force that they can generate through the conscious exertion of will, which he calls “maximal strength.” An ordinary person, he has found, can only summon about 65 percent of their absolute power in a training session, while a trained weightlifter can exceed 80 percent. Under conditions of competition a trained athlete can improve as much as 12 percent above that figure. Zatsiorsky calls this higher level of performance “competitive maximum strength.” This parameter is not a fixed number — the more intense the competition, the higher it can go, as the brain’s fear centers progressively remove any restraint against performance.

But there’s a limit to how fast and how strong intense pressure can make us. We’ve all heard stories about panicked mothers lifting cars off their trapped babies. They’ve been circulating so widely, for so long, that a great many assume that they must be true. Zatsiorsky’s work, however, suggests that while fear can indeed motivate us to approach more closely to our absolute power level than even the fiercest competition, there’s simply no way to exceed it. A 100-pound woman who can lift 100 pounds at the gym might, according to Zatsiorsky, be able to lift 135 pounds in a frenzy of maternal fear. But she’s not going to suddenly be able to lift a 3000-pound car.