It's unlikely sexual abstinence has any physiological benefits related to performance in athletes, a Hamilton sports physician says.
The idea was an "urban myth'' and the benefits would be purely psychological, Chris Milne said.
His comments follow a failed Telecom campaign to urge rugby fans to abstain from sex during the Rugby World Cup in support of the All Blacks.
It pulled the tongue-in-cheek "Abstain for the Game'' campaign, due to be fronted by former All Blacks captain Sean Fitzpatrick, after a negative public reaction.
Dr Milne said the theory about abstinence and performance was "as old as the hills''.
Abstinence might be used by coaches as a psychological tool with pent-up energy being a possible benefit, Dr Milne told the New Zealand Doctor magazine.
Condom manufacturer Durex has also rubbished the campaign, saying the argument for it was "misguided''.
"There isn't any scientific proof that sex negatively impacts on athletic ability - in fact, there are plenty of proponents of the idea that it actually improves performance,'' Durex spokesman Adonis Souloglou said.
He pointed to top tennis players Andy Murray and Francesca Schiavone, who had openly admitted they did not avoid or they actually chose to have sex before a big match.
"We'd hate for fans - and any of the players - to miss out on weeks of great sex all for nothing,'' Mr Souloglou said.
Meanwhile, Auckland District Health Board today launched a campaign encouraging safe sex during the World Cup.
The "Play safe, play fair'' campaign uses slogans like "consent, crouch, touch, condom, engage'' to promote condom use and get people thinking about sexually-transmitted infections and pregnancy.
"We don't believe simply telling people to abstain from sex as a single strategy is a realistic way of sending out effective messages about sexual health,'' Auckland Sexual Health Service (ASHS) programme supervisor Nick Laing said.
Posters and condom wallets will be distributed throughout the Rugby World Cup as part of the campaign.
ASHS doctor Nicky Perkins said the campaign acknowledged the reality of increased sexual activity and alcohol consumption, which was linked with unplanned sex, during large sporting events.
Although the Telecom campaign was intended as a joke and not a sexual health campaign, she was glad it was pulled because it wasn't very useful, Dr Perkins said.