Athletes' ability to push themselves to the limit is created by the brain's need to win, a new survey has revealed.
Dr Jo Corbett, senior lecturer in applied exercise physiology at the University of Portsmouth, has found that the brain of an exhausted athlete can tap into the body's anaerobic energy sources to fuel that final push for victory.
In his study sportsmen racing against someone else managed to find an extra burst of energy that increased their performance by 1.7 per cent.
"Most sportspeople know they perform harder and better when they are competing, but until now we didn't know precisely why," the Scotsman quoted Dr Corbett as saying.
"Whenever you do exercise you're likely to think 'how much am I willing to hurt myself?' and there's usually a point which holds you back because you don't want to do yourself irreparable damage.
"But when racing someone head-to-head, the athlete's brain can manipulate this signal and keep on going," he stated.
Out of 14 cyclists participating in the study, 12 were significantly faster in the final race, when they believed they were competing against an opponent.
Dr Corbett added: "In each race the participants cycled vigorously until they were completely exhausted but it was only in the last race, when they were unknowingly competing against themselves, they were able to race even harder.
The study was published in the journal Medicine, and Science in Sports and Exercise