Suddenly engaging in sexual activity, or any exercise for that matter, could put you at higher risk of having a heart attack if you lead a sedentary lifestyle.  

Researchers at the Tufts Medical Centre in the United States analysed 14 studies that focused on the link between physical exertion and the risk of heart attacks, and found that people are 3.5 times more likely to have a heart attack when they are exercising.

Furthermore, we are 2.7 times more likely to have a heart attack during or immediately after sexual activity, since the acceleration in heart rate may go beyond normal

The relative risk of a heart attack caused by an increase in physical activity is at about 45 percent for each additional time a person indulges in it per week. But this risk falls if exercise becomes regular.

The research suggests that people who have sex and/or exercise regularly may reduce their risk of cardiac arrest by a whopping 30 percent.

"What we really don't want to do is for the public to walk away from this and think exercise is bad," Jessica Paulus, a researcher at Tufts, told Reuters.

The researches say that they are not discouraging people form exercising, but rather advising those who are not active to increase the intensity of their exercise regime gradually rather than risking any major strain on their hearts.