Two British anthropologists who analysed four events at the 2004 Athens Olympics have recommended an entirely legal stimulant to enhance performance - red uniforms.

According to them, competitors wearing red were more likely to emerge victorious, reports the Los Angeles Times.

"We were pretty bowled over when we looked at the data," said Robert Barton, who published a paper on this with Russell Hill, his colleague at the University of Durham, Britain.

Barton and Hill specialise in studying the role of colour in non-human primate societies. Red is the colour of male dominance in several other species, they said.

For example, in mandrill monkeys, a male that takes over a group quickly develops red markings that make his authority known to all. But little is known about the role of red in the human social order.

The anthropologists wanted to test whether red could influence competition between humans.

Barton and Hill saw the 2004 games in Athens as the perfect opportunity. In four sports - boxing, taekwondo, Greco-Roman wrestling and freestyle wrestling - the competitors were randomly assigned red or blue uniforms. All of them were male.

In each sport, athletes in red won more often. Overall, the red-clad competitor won 54.9 percent of the time, or 242 out of 441 total match-ups, the study showed.

To make sure other factors were not at work, the researchers examined matches in all 29 weight classes and in all 21 rounds of competition from the opening contests to the finals. In 19 weight classes and 16 rounds, there were more red winners, they found.

The researchers realised that the most powerful factor in a competition was ability. Barton said wearing a red uniform cannot tip a contest when one athlete is clearly stronger or more skilled.

But the analysis suggested red did have the power to sway an even match. To check their analysis, they looked at the closest matches - those with the lowest margin of victory between equal competitors. In these cases, red won at an even higher rate, more than 60 percent.

Barton and Hill also looked to see whether red had the same role in a team sport. In the Euro 2004 soccer tournament, five teams wore two uniforms - one red and one not red - over the course of the competition.

In red, each team scored more goals, the researchers said.

Is it time for sports to ban red to make competitions fair? "That is up to the regulators," Barton said.