LONDON (Reuters) - Forget pretending you are talking to one person or concentrating on a single point in the audience -- having sex is good way to calm nerves before giving a speech or presentation.

But Stuart Brody, a psychologist at the University of Paisley in Scotland, said it has to be full sexual intercourse to get the best results.

He studied nearly 50 men and women who recorded their sexual activities for two weeks and analysed its impact on their blood pressure levels when under acute stress, such as when giving a speech.

Brody discovered that the volunteers who had sexual intercourse were the least stressed and had blood pressure levels that returned to normal more quickly than people who engaged in other types of sex.

But people who had abstained from sex had the highest blood pressure response to stress.

Even after taking into account stress due to work or other factors, the range of responses to stress were best explained by sexual behaviour.

"The effects are not attributable simply to the short-term relief afforded by orgasm but rather, endure for at least a week," Brody told New Scientist magazine said on Wednesday.

He believes that the release of the so-called "pair bonding" hormone oxytocin might explain the calming effect.