LONDON, June 16: If watching the World Cup with a drink in your hand is your perfect idea of unwinding, you might need to find a better way to relax, say British researchers examining stress levels in soccer fans.

With funding from online betting firm Betfair, Loughborough University scientists are measuring at every England game the strains experienced by supporters as well as the added impact of having a bet on the contest.

The researchers monitor fans' heart rates throughout the match, take their saliva samples before kick-off, at halftime and after full time and then map the results against a recording of the game.

“We may be able to see whether England supporters tend to get more stressed or anxious,” biochemist and sports scientist Mike Gleeson said during England's match with Trinidad & Tobago on Thursday evening.

Previous studies have shown that sporting fervour can lead to anxiety, panic and even heart attacks in some soccer fans, although winning the World Cup can boost a nation's health or feeling of well-being.

Gathered in a room in west London with Thursday's game projected on to a wall, both groups of fans -- 10 on each side -- looked excited and reacted to every near-goal and every last-second save. There were loud cheers or gasps and even jumps and dance routines.

“I never get stressed, more anxious,” said participating England fan Ben Fox, 32, after a tense but goalless first half.

“We shouldn't have to depend on a kid (Wayne Rooney), it annoys me,” he added.

Rooney came on in the second half, passed fit to play after his injury saga.

Fellow supporter Jefferson Lovell, 23, sounded equally downbeat at half time. “It's typical England: too much expectation, not enough performance,” he said.

Exactly how stressed each fan has become is assessed from their heart rates, taken every five seconds and then averaged by a computer over each minute. Saliva volumes and composition are measured and there are questionnaire responses.

During the first experiment at the England-Paraguay game last Saturday some fans' heart rates rose to 95-100 a minute compared with the normal 70, Gleeson said.—Reuters