If you don’t have time to exercise during the week, longer workouts on the weekend can be just as good for your heart.

Adults should get 150 minutes of moderate to vigorous activity per week, most the guidelines recommend, with the typical advice to distribute it throughout the week. The Harvard researchers were surprised to find that people who packed their 2.5 hours of activity into one or two days reduced their risk of heart attack by 27%, compared with 35% among people who exercised more on weekdays. «Weekend warriors» also experienced a 38 percent reduced risk of heart failure, compared with 36 percent among those who exercised regularly, the new study published Tuesday in JAMA found.

«The idea of ​​being able to cram everything into one weekend or two days a week was a bit of a surprise,» said the study’s co-author. Dr Patrick Ellinoracting chief of cardiology at Massachusetts General Hospital and professor of medicine at Harvard Medical School.

The bottom line, Ellinor said, is that «the goal is to get 150 minutes of moderate to vigorous activity a week, no matter how you do it.»

To take a closer look at how the timing of the exercise made a difference, the researchers turned to the UK Biobanka widely used database of 502,629 participants, ages 40 to 69, who enrolled between 2006 and 2010. For the new research, a subset of the group agreed to wear wrist-mounted accelerometers, which measure physical activity 24 hours a day.

Ellinor and her colleagues focused on 89,573 of the participants who wore the accelerometers for one week, most of whom were followed for 6.3 years. The researchers characterized the participants as weekend warriors, regular or inactive athletes.

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A major limitation of the study is that the activity data was collected for only one week, Ellinor said, so they don’t know if the participants continued the same exercise pattern during the follow-up period.

Still, the take-home message is that people should get 150 minutes of moderate to vigorous activity each week, «however they can do it,» said Dr. John McPherson, a cardiologist and professor of medicine at Vanderbilt University Medical Center in Nashville.

«It can be clustered over two days or it can be 25 to 30 minutes every day,» said McPherson, who was not involved in the new research. “The really important thing is to maintain the 150 minutes a week.”

How to avoid exercise injuries

One argument against compressing exercise into two days is the higher chance of injury reported in some studies of weekend warriors. But experts say that people who are careful to develop an exercise program and warm up and cool down properly can avoid such injuries.

If you’re going to cram all your exercise into two days, you really need to build it up, said Keith Diaz, an exercise physiologist and associate professor of behavioral medicine at Columbia University’s Vagelos College of Physicians and Surgeons.

“The biggest concern is overuse injuries,” said Diaz, who was not involved in the new research. “You can’t go from zero to 60 in two days. There are many weekend warriors without injuries, but their bodies have acclimated.

The type of activity you choose is also important, Diaz said. While you’ll want to choose something you enjoy doing, low-impact activities like swimming and biking are a better option because they’re less likely to damage your joints, he added.

Because the adult body begins to lose condition after three days of inactivity, limiting workouts to the weekend will not be the path to peak physical performance, Diaz said.

«You’re constantly fighting the body’s tendency to go back to the disused state,» he explained.

The new study offers good news, said Glenn Gaesser, a professor of exercise physiology at Arizona State University’s College of Health Solutions.

«It didn’t really matter how people divided up their exercise throughout the week, as long as they did at least the minimum amount of moderate to vigorous activity,» Gaesser said.

For people concerned that exercising just one or two days a week could increase injury risk, previous research shows it’s mostly due to contact sports, said Gaesser, who was not involved in the new research.

Calling people in the study «weekend warriors» is somewhat misleading, since most do not engage in «warrior» activities, Gaesser said. “The vast majority are doing typical cardio activities like walking, biking, etc. Those who participate in contact games are more likely to get injured.”

To avoid injury from prolonged workouts, pay attention to what your body is telling you, said Dr. Gregory Katz, cardiologist at NYU Langone Heart and assistant professor of medicine at NYU Grossman School of Medicine.

«Don’t ignore that nagging pain,» said Katz, who was not involved in the new study. “Does it feel like the kind of stress you should be putting on your body or something that could be harmful?”