Does Any Amount of Leisure-Time Running Reduce Your Risk of Heart Attack?

The skeptical cardiologist dislikes running. When I start running my whole body seems to be telling me I am making a serious mistake. After running, my knees hurt (worse than the normal level of pain) and if I do enough of it, my hips hurt too.
Despite this, I have incorporated running into my exercise routine over the last few years since I stopped playing tennis. I primarily get my aerobic exercise now by using elliptical type devices and I try to get at least 150 minutes of vigorous elliptical work per week. About once a week, I run a mile on a treadmill at 6 MPH.
My current patient exercise recommendation is for 150 minutes of moderate intensity aerobic exercise.  I have advised patients in the past, that walking at a moderate pace was adequate exercise, and I’ve felt, based on prior studies, that running was not necessary to achieve the cardiovascular benefits of exercise.

Any Running Associated With Lower Risk of Dying

A new study published recently in JACC has made me reconsider this advice.
As part of a prospective longitudinal cohort study at the Cooper Clinic in Dallas, Texas, Lee, et al. looked at data from a group of 55,137 adults on whom they had information on running or jogging activity during the previous 3 months.
To reduce confounding bias in the association between running and mortality, the total amount of other physical activities except running was adjusted in all multivariable regression models.
They obtained information on death from The National Death Index and over 15 years found 3,413 all-cause death and 1,217 deaths from cardiovascular disease.
Those individuals who described themselves as having done any running in the last 3 months had a 30% lower risk of all-cause mortality and a 45% lower cardiovascular mortality.
As you might expect, the non-runners were older, smoked more and were fatter. The investigators ran analyses that controlled for the differences in these factors. The protective effect of running, even a small amount, persisted, regardless of age, gender, body mass index, smoking or alcohol consumption.
Amazingly, it didn’t matter how much you ran.
This finding is quite remarkable.
Those who ran <51 minutes per week did just as well as those who ran >176 minutes per week.
Of the 20,67 that had two examinations, those who were runners at both examinations had the best outcomes with a 50% lower risk of CVD mortality.
These findings are not definitive. We need more studies in this area but they are food for thought.

Why Would Running Be A Better Form of Exercise For Your Heart

Some thoughts…
Perhaps the person who doesn’t want to run has a fundamentally different mindset about his/her health than the person who is willing to run just a little bit. Does this inclination to run mirror the person’s overall approach to their health? We can assess factors like cigarette smoking, obesity, diabetes and cholesterol but there are likely (so far) intangible factors that contribute to our health that tend to cluster with a pro-active health attitude.
Why do I run? After all, I don’t like it, it hurts my knees and I didn’t think it was contributing to my overall health. I did the mile run for a few reasons:
Running a mile in 10 minutes served as a milestone, a fixed goal if you will, for my cardiovascular fitness. I can get a very good idea of where I’m at by measuring my heart rate. I’m 60 years old and my predicted maximal heart rate (220 minus age) is 160. When I’m out of shape, my heart rate will get as high as 155 BPM during the mile, when in shape it is 10 BPM lower. 145 BPM is 91% of my predicted maximal HR.
My sense is  that a good goal for cardiovascular fitness is to get the heart rate up to 90% or so of your predicted maximal. It may be that running more reliably gets you to that threshold than other activities.
Also, as the significant other of the skeptical cardiologist points out, “you can’t cheat at running.” There’s a certain amount of effort you have to put into it and there’s no way to escape it as there is on a bicycle or an elliptical. With walking you could choose a speed ranging from the snail-like up to 4 MPH or so.
Those who don’t run may also have orthopedic limitations (plantar fasciitis, osteoarthritis, rheumatoid arthritis) or pulmonary problems (COPD, asthma) or undiagnosed heart problems (heart failure, valve defects, rhythm problems) that are not captured by the examinations the investigators performed.
These findings, the authors of the paper suggest, may make people more likely to run:

“Because time is one of the strongest barriers to participate in physical activity, this study may motivate more people to start running and continue to run as an attainable health goal for mortality benefits. Compared with moderate-intensity activity, vigorous-intensity activity, such as running, may be a better option for time efficiency, producing similar, if not greater, mortality benefits in 5 to 10 min/day in many healthy but sedentary individuals who may find 15 to 20 min/day of moderate-intensity activity too time consuming.”

Some Possible Mechanisms For The Benefits of Running

As I was putting the finishing touches on this post I notice that the Sept 23 issue of the Journal of the American College of Cardiology sitting in front of me has two articles that are directly relevant to this issue. I haven’t had time to analyze these in detail but the conclusions of the first study  are that

“low doses of casual, lifelong exercise do not prevent the decreased compliance and distensibility observed with healthy, sedentary aging. In contrast, 4 to 5 exercise sessions/week throughout adulthood prevent most of these age-related changes”

Thus, the mechanism through which running or more “committed” exercising improves survival could be mediated through improving the diastolic properties of the heart.
I spent most of my academic cardiology career studying diastolic function and it is an incredibly complicated and poorly understood area. Simply put, the heart has to contract to pump out blood (we call this systole) then it has to fill back up with blood (we call this diastole). With aging, the heart’s ability to contract doesn’t change but its ability to fill changes dramatically. Thus, diastolic properties become impaired with aging and this study suggests that dedicated regular exercise prevents that.
The other study showed that regular exercise helps to slow  age-related increase in blood pressure.  Lower blood pressure with aging could be a mechanism for preventing the age-related decline in diastolic performance of the heart.

Changing Exercise Prescription

From now on when I talk to my patients about exercise, I will inquire about running specifically and I’ll mention these studies which suggest a little running may go along way toward forestalling the aging process of the heart and lowering their risk of dying.