Some top soccer players are under-performing because of worries about gambling losses, new research says.

Players are also using online betting sites to conceal their gambling from their partners, the British Sociological Association's annual conference in Birmingham was told today.

Graeme Law, of the University of Chester, interviewed 34 current and former professional football players, including international and Premiership players as well as those in lower leagues.

Players talked about how worries caused by gambling – usually poker games on the coach or at hotels before matches – had impaired performances on the pitch.

"Players gamble as a way of relieving the boredom on journeys to away games and after training on pre-season tours," said Mr Law, who carried out the research as part of his PhD. "Contrary to popular opinion, their actions are heavily regulated and constrained, so they get easily bored."

But gambling losses could affect their performance. "Players were unable to function to the level expected, and this leads to resentment in the team about their gambling."

One Premiership player told Mr Law: "I have lost a lot and I had a stinker because it's all I thought about during the game."

One Premiership player said of a team-mate: "On the way to the game he lost about two grand, and he was only 18. Now he had a shocker in the game."

One former Championship player said: "I have seen a lot of players lose a lot of money and when they get to the game they have a bad experience or a bad game…when I became a manager I tried to ban cards…but you can't really stop it."

Mr Law told the sociology conference that players turned to online gambling to keep their habit secret from their partners.

"Previous gambling environments were more social and encouraged group interaction, whereas the internet now allows gambling to be done in private."

One international and Premiership player told him: "I liked to bet on the bus, but it got worse when I could bet online. I was able to do it all the time with no one knowing. I lost a lot. My wife found out after a year or so and she got me help and it's under control now. It's the culture to gamble in football and it can get dangerous when it grips you."

Mr Law told the conference: "An unintended outcome of the development of technology has been that partners have a lack of awareness of potential gambling problems that can arise for players."

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