Researchers analyzed data from more than 28,000 people in Europe who suffered a heart attack in order to see how active or more "couch potato" lifestyles affected their risk of death.

Higher levels of physical activity were associated with a lower risk of death immediately and within 28 days.

Those who had engaged in moderate levels of activity had a 33% lower risk of immediate death. At 28 days, they had a 28% lower risk of death, the study found.

"Almost 18% of patients with a heart attack died within 28 days, substantiating the severity of this condition. We found an immediate survival benefit of prior physical activity in the setting of a heart attack, a benefit which seemed preserved at 28 days," said study author Dr. Kim Wadt Hansen, from the department of cardiology at Bispebjerg Hospital in Copenhagen, Denmark.

Researchers said the findings provide strong support for European guidelines recommending healthy adults of all ages get at least 150 minutes a week of moderate intensity or 75 minutes a week of vigorous intensity aerobic activity, or an equivalent combination.

Heart disease is the leading cause of death worldwide.