London: Men who possess a winning streak in every competition are likely to have higher testosterone levels and cheat on their spouse or partners, finds a study.

The findings showed that just being convinced that they have won, or bested another man, is enough to cause male hormonal fluctuations that can influence sexual behaviour.

This leads to a hormonal and psychological shift, which gives them an inflated sense of their own value as a sexual prospect and makes them more inclined to approach new potential partners.

"The endocrine system that controls hormones is responsive to situational changes. Previous research has shown that testosterone is lower when men are in a committed relationship, or have children, to promote long-term mating strategies," said lead author Danny Longman from Britain's University of Cambridge.

"Our results show that both testosterone and its corresponding psychological effects can fluctuate quickly and opportunistically, shifting towards short-term mating in response to a perceived change in status that may increase mating value," Longman added.

For the study, published in the journal Human Nature, the team used a simple proxy for social and sexual competition by pitting athletic young men against each other to see who was the most powerful rower.

The team measured hormone levels, as well as self-perceived attractiveness and confidence in approaching women, in a small group of men in their twenties before and after competing in head-to-head battles on rowing machines.

They took saliva samples to test hormone levels before and after the races.

Overall, men who thought they were winners had testosterone levels 14.46 per cent higher than their opponents.

And these men demonstrated a "self-perceived mate value" that was 6.53 per cent higher, on average, than their rivals, and were 11.29 per cent more likely to approach attractive women in an effort to instigate sexual relations, the researchers said.