Devoted football fans experience such intense levels of physical stress while watching their team they could be putting themselves at risk of a heart attack, research suggests, the BBC reports.
The Oxford study tested saliva from Brazilian fans during their historic loss to Germany at the 2014 World Cup.
It found levels of the hormone cortisol rocketed during the 7-1 home defeat in the semi-final.
This can be dangerous, increasing blood pressure and strain on the heart.
The researchers found no difference in stress levels between men and women during the game, despite preconceptions men are more “bonded to their football teams”.
“Fans who are strongly fused with their team – that is, have a strong sense of being ‘one’ with their team – experience the greatest physiological stress response when watching a match,” said Dr Martha Newson, researcher at the Centre for the Study of Social Cohesion, at Oxford.
“Fans who are more casual supporters also experience stress but not so extremely.”
Prolonged high levels of cortisol can: constrict blood vessels, raise blood pressure, damage an already weakened heart.