When it Comes to Jogging, Easy Does It: Study

Research suggests that some jogging can help improve your health. But, not enough could be harmful.

"In this study, the dose of running that was most favorable for reducing mortality was jogging 1 to 2.4 hours per week, with no more than three running days per week," said study researcher Jacob Marott of the Frederiksberg Hospital in Copenhagen, Denmark. According to Marott, the slowest pace (or average) was about five miles per hour.

Marott, his coworkers and a small group of healthy Danish adults followed more than 1,100 joggers over a period of 12 years. These joggers recorded how often they jogged and what their perceived pace was.

Investigators discovered that strenuous runners were twice as likely to be killed during this time frame as non-joggers. Marott's team concluded that moderate and light joggers performed better in this order.

These findings were made available online February 2, ahead of their publication in the February 10 issue of the Journal of the American College of Cardiology.

Strenuous running can be dangerous. Marott explained that long-term endurance running may cause structural changes in the large and heart arteries.

But, an American researcher says the issue of optimal running intensity for longevity remains unresolved.

D.C. Lee, assistant professor in kinesiology at Iowa State University and author of an editorial that accompanied the new study, admitted there are limitations to this study.

Lee studied 55,000 adult joggers, which included more than 13,000 runners. He found that joggers who ran the most frequently and for a longer time had a lower chance of dying over the following period than non-runners. This study was published in the Journal of the American College of Cardiology, in 2014.

Joggers were asked to report their running speed in the Copenhagen study. The researchers found that even the slower joggers could get vigorous exercise.

Marott stated that the reported pace did not reflect an absolute speed in miles per hour, but subjects' perceptions of their pace as being slow, average, or fast. Marott said this is more accurate than an absolute scale, especially when the range of ages in their study was as large (20-95 years). He said that the average or slow pace was approximately 5 miles an hour, or around a 12 minute mile. The fast pace, on the other hand, was roughly 7 miles an hour, or about an eight-minute mile.

The study's background data shows that 54 million Americans regularly run. Nearly 2 million people completed half marathons in 2013. More than 540,000 finished marathons (26.2 mi).

Lee stated that the study had one limitation: a small number of people logged the longest jogging hours. Lee said that only 47 of the joggers logged over four hours per week while 80 ran at least three times per week. Lee explained that the small number of joggers could have affected results and comparisons.

Lee stated that researchers did not examine more than three thousand active non-joggers, who also exercise in different ways. He said that researchers focused on death due to all causes and not how high running miles or times affect certain types of deaths. That could have yielded more precise information regarding potential dangers.

He said that running may make you more susceptible to cardiovascular disease. Lee's team also examined the effect of running on death rates. They found that runners died less from all causes than non-runners. However, there was an apparent trend to lower benefits from high doses of exercise.

Lee noted that even though the research showed a benefit, it was still better than not running at all. He believes this might encourage sedentary individuals to move more.

Marott and his colleagues discovered a link between light running and higher survival rates. However, the relationship was not causal.

The American Medical Athletic Association's executive director Dave Watt stated that "the study shows that running is still a better choice than prescribing any form of exercise as a part a healthy lifestyle" and added, "Basically the study still indicates it's an even better option to prescribe some type of running as a component of a health lifestyle.