The Physical Activity Guidelines for Americans recommend adults engage in high-intensity exercise, such as running, for a minimum of 75 minutes a week. But a new study from Iowa State University suggests that running at a slow speed for just 5-10 minutes a day can significantly reduce mortality risk, and running for any longer may actually do more harm than good.

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Running just 5-10 minutes a day could increase life expectancy, according to researchers.

The research team, led by Duck-Chul "D.C" Lee, an assistant professor of kinesiology at Iowa State, recently published their findings in the Journal of the American College of Cardiology.

For their study, Lee and colleagues assessed the data of 55,137 adults between the ages of 18 and 100 years, who were followed-up for an average of 15 years.

Participants' physical activity habits were disclosed through a medical history questionnaire.

The team also analyzed the causes of any deaths that occurred during the follow-up, before looking at the amount of exercise each individual participated in every week.

Running could add 3 years to life expectancy

During the follow-up period, 3,413 participants died from all-causes, while 1,217 died from cardiovascular causes. Of these, 24% participated in running on a weekly basis.

The team found that participants who engaged in running each week were 30% less likely to die from all-causes and 45% less likely to die from cardiovascular causes, compared with those who did not participate in running. Overall, runners were likely to live 3 years longer than non-runners.

But most interestingly, the researchers found that these reduced mortality risks were the same among participants who ran less than an hour a week and those who ran more than 3 hours a week. Even those who ran 5-10 minutes a day at a slow speed showed significantly reduced all-cause and cardiovascular mortality risk, compared with non-runners, according to the team.

Lee says:

"Running is good for your health, but more may not be better. You don't have to think it's a big challenge. We found that even 10 minutes per day is good enough. You don't need to do a lot to get the benefits from running."

Lee explains the findings further in the video below:

Too much running may be bad for you

Lee notes that it may actually be better to run for only 5-10 minutes a day, as running for long periods could cause more harm than good.

It could cause bone or joint damage, for example, and even heart attacks. Last year, Medical News Today reported on a study published in the Canadian Journal of Cardiology, suggesting that marathon running may be bad for the heart.

"With too much of vigorous-intensity aerobic exercise, there might be a side effect," says Lee. "Is there any limit that we shouldn't go over? It is possible that people who do too much might be harming their health."

But he notes that further studies looking at the side effects of high-intensity exercise need to be conducted before any firm conclusions can be made.

For now, the researchers say their findings emphasize the significant health benefits that can be gained from just running a few minutes each day.

"This study may motivate healthy but sedentary individuals to begin and continue running for substantial and attainable mortality benefits," they conclude.

Christopher Allen, senior cardiac nurse at the British Heart Foundation in the UK, says that many people do not manage to achieve the current recommendations for weekly physical activity, but he notes that this study shows how small amounts of exercise can go a long way.

"What this study proves is that when it comes to keeping physically active, every step counts towards helping you maintain a healthier heart," he says. "Breaking your exercise down into 10-minute chunks can make this goal much more achievable and can help prolong your life by reducing your risk of dying from cardiovascular disease."

This is not the only study to suggest less is more when it comes to exercise. A 2013 study published in the journal Arteriosclerosis, Thrombosis and Vascular Biology claimed that walking reduces heart risk as much as running.