The pulse-pounding action of an NHL game can elevate a fan's heart rate to the same levels achieved during vigorous exercise, and may pose a health risk to patients with cardiovascular issues, according to a new study of Montreal Canadiens fans watching the sport.

The study, which was conducted by researchers in Montreal and two high school students, found that spectators' heart rates increase by 110 per cent when watching a live hockey game, and 75 per cent when watching a game on television.

That intensity is equivalent to vigorous and moderate exercise, respectively, and can place substantial stress on the cardiovascular system among vulnerable patients, the authors suggest.

Overall, watching hockey was found to elevate a healthy person's heart rate by an average of 92 per cent.

The study was the brainchild of high school students Roxana Barin, 14, and Leia Khairy, 13, whose father is one of the authors.

The girls told CTV News that both of them play competitive sports, and started wondering whether the spectators at their games, including their parents, experience heart stress during intense moments.

"We see our parents and they stress so much on the field," Barin said. "So we wanted to see, watching a game, how much that affected them."

Senior study investigator Dr. Paul Khairy, a professor at the University of Montreal's Montreal Heart Institute, said he thought the girls had "an excellent idea."

"The girls demonstrated that it is exciting to watch the Montreal Canadiens," he told CTV News. "That the heart rate response is an impressive heart rate response, especially at a live game that is equivalent to vigorous physical activity and these types of heart rate responses do carry the potential in people who are at risk who are otherwise susceptible."

Twenty adult Montreal Canadiens fans wore heart rate monitors for the study, with half of them watching the games at home and the other half watching live at the Bell Centre.

Most of the adults were healthy, although one had hypertension, one had Crohn's disease and one had mild asthma. Base heart rates were established beforehand, and the subjects were also given a simple questionnaire asking about their health and level of fandom. The testing was administered by high school students from Royal West Academy in Montreal.

According to the results, heart rates spike during high-intensity moments for or against the individual's favourite team, such as during a scoring chance, a powerplay or an overtime period. Fandom and the final result of the game were found to have little impact on heart rate.

"If someone has a known cardiac disease, it is always prudent to ensure with a person's physicians that they are on optimal therapy to protect themselves against risks such as watching hockey games and other risks in daily life," Dr. Khairy said.

But he added that people shouldn't be discouraged from "enjoying life" and watching their favourite sports teams.

The findings are published in the October 5 edition of the Canadian Journal of Cardiology, along with an editorial by doctors David D. Waters and Stanley Nattel, who were not part of the investigation.

Waters and Nattel credit the study authors with pointing out the largely unaddressed risk factor that watching hockey might pose to heart patients.

"At-risk patients should be warned about potential CV symptoms," the authors write.

They also offer a tongue-in-cheek evaluation of the risks posed by a potential Stanley Cup win for the Toronto Maple Leafs or the Montreal Canadiens. However, their conclusions fall short in suggesting that "that risk does not seem imminent," as they appear to have overlooked the presence of Auston Matthews on the Leafs' roster.

With files from CTV's medical affairs specialist Avis Favaro and producer Elizabeth St. Philip