Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance

by Alex Hutchinson

There are other reasons to avoid dulling the pain too much. In a series of experiments starting in 2009, researcher Markus Amann, then at the University of Wisconsin, investigated what happens to cyclists when they can’t feel pain at all. Amann and his colleagues injected the nerve blocker fentanyl into the spines of their volunteers, preventing signals from traveling up from the leg muscles to the brain, and asked them to ride 5K as hard as they could on a stationary bike.15 The effects were dramatic. The volunteers had been given a gift that many athletes dream of—the ability to push as hard as they wanted without feeling pain—and they took advantage of the opportunity to ride themselves into a smoking ruin. By the end of the time trial, the riders couldn’t even get off the bikes by themselves. Some couldn’t even unclip their feet from the pedals, Amann recalls, “and not a single one was able to walk.”