cyclists were told to pedal a stationary bike at top speed for the equivalent of 4,000 meters. Later they repeated the task while watching an avatar of themselves pedaling in the earlier time trial. What the cyclists didn’t know was that the researchers had turned up the speed on the avatar. And yet the cyclists were able to keep up with their avatars, surpassing what they thought had been their top speed. “It is the brain, not the heart or lungs, that is the critical organ,”