Another reason treading on a LEGO brick hurts “has a lot to do with the concentration of nerves on the bottom of your foot,” says Dr. Lauren Geaney. She’s a foot specialist at UConn Health in Connecticut. Nerve cells send messages throughout the body, including telling the brain when something is painful (see How You Feel Pain). The sole of the foot has about 200,000 nerves. That’s 10 to 20 times more nerves than in the skin on your leg. All those nerves magnify the sensations felt on the bottom of the foot, says Geaney.
Both Geaney and Wood-Black agree that classic, rectangular LEGO bricks are the worst to step on. Because they’re thick, their edges dig farther into your foot, agitating loads of nerve endings. OUCH!