A new study finds firefighters who died of stroke, heart attack, or other vascular events on the job were typically doing vigorous physical activity right before the attack. 

"It's interesting because they found that quite a number of the people that had a heart attack or stroke were engaged in aggressive physical activity- firefighting or something to that effect," said Dr. Jennifer Frontera, who did not take part in the study but treats stroke at Cleveland Clinic.

Researchers at the Zeenat Qureshi Stroke Institute in St. Cloud, Minnesota collected data from the National Institute for Occupational Safety and Health from 1998 to 2012.

They found of the 199 fatal cardiovascular events firefighters had while on duty, 88 were actively engaged in fighting a fire. 35 percent of the events were triggered by fitness training or heavy lifting at the fire station.

Researchers say firefighters or anyone who must perform vigorous, physical activity at work should be aware of the signs and symptoms of a heart attack or stroke. They also recommend screening for risk factors among employees. Frontera agrees.

"Family history of stroke or heart attack, elevated cholesterol, abnormal heart rhythms are also a big risk factor, if you have any of those things, as well as smoking, which you certainly should stop doing," explained Frontera. "If you have any of those risk factors it's really important to go see your doctor and work on a plan to try to get them under control."