Alison Cope goes to the gym four times a week, and after 20 minutes on an exercise machine her heart rate reaches 135 beats per minute (bpm).
But it only takes one goal from Wayne Rooney to send it skyrocketing to 160bpm.
As part of a BBC experiment, Ms Cope, 37, from Derby, wore a heart monitor as she watched England’s Euro 2004 game against Switzerland.
It showed large peaks for each of England’s three goals, and a smaller peak when striker Wayne Rooney was shown a yellow card.
With such stresses being put on the heart, it is little wonder that researchers warn of the health hazards associated with watching football.
Ms Cope said: “I wasn’t surprised my heart rate was high because I get so into the football.
“But I thought it was interesting that it was faster than when I’m pouring with sweat at the gym.
“I don’t think I’m at any risk because I am reasonably fit, but someone who spends all their life sitting on the couch and drinking would probably be at more risk.”
A Swiss study last year showed that deaths from heart attacks increased by 60% during last summer’s World Cup finals.
Separate research showed the number of heart attacks increased by 25% when England lost to Argentina in a penalty shoot-out at the 1998 World Cup.
University of Birmingham research fellow Dr Victoria Burns monitored Ms Cope’s heart rate for the BBC.
She said heart rates soared during exciting moments in football because of a “fight or flight” response.
She said: “If it was a response to a physical threat, the increased heart rate gets more oxygen to the muscles so you could run away.
“However, this is an inappropriate reaction when watching football, because no physical action from the spectator is required.”
Dr Burns said most people were not at risk of having heart attacks, but people who were unfit or drank a lot of alcohol needed to be careful.
“You can lower the risk by not drinking, not watching in a group environment and, of course, keeping the game in some perspective.”