It’s happened before. In 1982, Angela Cavallo lifted a 1964 Chevy Impala off her teenage son, Tony, who was working on the car’s suspension when the jacks failed and the car fell on him.

When we are under duress, the hormone adrenaline binds to adrenergic receptors on our muscle tissue, and actin and myosin—the proteins responsible for muscle contraction—bond faster. Adrenaline also increases the respiratory rate, which raises blood pressure and makes our heart pump harder and faster. Exercise physiologist William J. Kraemer, a professor in the University of Connecticut’s kinesiology department, says that our muscles can be 5 to 15 percent stronger in these conditions. We are limited, though, by our genetic capability and our muscle development. Adrenaline, Kraemer says, removes some inhibition and gives us a quick burst of strength.

If we’re as strong as Brian Shaw, we could use that strength to pull airplanes. Shaw is a professional strongman and a runner-up in the 2010 World’s Strongest Man Competition. He can deadlift 1,100 pounds. But, he says, he’s at his best in front of a crowd, when he’s pumped up, focused, “almost in fight mode.” An adrenaline rush from being in front of an audience can definitely help a lifter like Shaw, Kraemer says. Enough, even, to pull a semi truck. Lifting a car? Piece of cake.

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