Athletes who believe they have consumed caffeine perform better even when they have in fact had none, research shows.
In tests of four teams of cyclists, the group who knowingly took caffeine were the most successful. But a team who were told they had been given the drug but had been given a placebo produced similar results to another team given caffeine without their knowledge.
Michael Duncan, a senior lecturer in applied sports science at Coventry University, called the effect as a "self-fulfilling prophecy". He added: "We found there's a psychological mechanism whereby the person will react depending on what they think they've ingested, rather than what they've actually had. When we told them they were having caffeine but they had orange squash, they performed better".
"Their perception of how hard things were was also lower when we told [athletes] they had had caffeine. The trick is if you can convince them that some substance is going to have a positive effect, it will have that effect."