Thursday, June 22, 2017

Running and Your Heart, Part III: Coronary Artery Disease

Coronary arteries, as seen via cardiac catheterization.
Before we get into it, let's just reiterate that this post (or anything else you read on the blog) is NOT to be construed as medical advice.  This is for informational and general-knowledge purposes only.  Furthermore, while I have a pretty good grasp on this stuff, I'm NOT a cardiologist, and anything you might read here is subject to my own interpretations (or mis-interpretations).  As such, this blog should not be taken as a substitute for medical care by a qualified professional.  I'm happy to provide information and try to answer people's questions.  But I AM NOT YOUR DOCTOR.

That being said...this blog is getting awful science-y.

In my continuing effort to either confuse the shit out of you, or freak you out (no, no, JK), I thought we'd delve a bit more into the relationship between distance running and heart health/disease by focusing on the coronary arteries.  Last time I talked about the normal adaptations the heart makes to endurance exercise ("the athlete's heart") and how these adaptations can be both beneficial and, in some cases, harmful.  In that post we quickly glossed over the coronary arteries, but today we're going to examine that aspect of the cardiovascular system in greater detail, because it's extremely important and because a lot of recent research has examined this relationship closely.

Recall from last time that the arteries carry oxygen-rich blood from the heart to the various muscles, tissues, and organs of the body, supplying them with the oxygen necessary to perform their particular functions.  The coronary arteries run directly over the heart muscle itself, bringing oxygen to the heart tissue and allowing the heart muscle to fulfill its ceaseless task of pumping blood throughout the body.  Given the heart's position of primacy in the body, you can see how the entire system relies to large extent on the uninterrupted flow of blood to its muscle.

As discussed previously, the term "heart disease" can encompass a wide variety of problems with the various physiologic systems at play in the heart: anatomic, structural, electrical, etc.  But most commonly, when someone refers to "heart disease," they mean an abnormality within the coronary arteries that compromises the flow of blood and the delivery of oxygen to the heart muscle.  This can take the form of stenosis, a hardening and narrowing of the artery that can disrupt blood flow.  Such narrowing occurs when various junk, usually cholesterol, builds up within the lumen of the artery.  (Picture a pipe or a hose that gets clogged with dirt and how that affects the flow of water through it.)  Over time, these plaques can harden and calcify, causing the artery to narrow and stiffen.  These stiff, narrow arteries thus lose their ability to dilate (expand) in response to an increased demand for oxygen--for example, during exercise.  So when a heart with narrow, inelastic coronary arteries is placed under the stress of exertion, the arteries cannot expand to meet that increased demand, and the heart muscle suffers from a lack of the necessary oxygen, called ischemia.  (This is the most common reason someone would have chest pain with exertion, also termed angina.)  Sometimes, a piece of these plaques can break off and become dislodged from the inner wall of the artery, travel downstream, and get stuck in a narrower part of the artery, causing a near-complete or complete cessation of blood flow to a particular part of the heart.  If prolonged, this can lead to infarction, or death of this part of the heart muscle: what is commonly known as a "heart attack."

So why do people get coronary artery disease?  Well, part of it is genetic; if your parents or siblings have coronary artery disease, you're more likely to suffer from it as well, and obviously you can't do anything about that.  But there are many modifiable risk factors for coronary stenosis, such as high blood pressure, diabetes, and smoking, that you can do something about.  And running helps with these factors: regular aerobic exercisers have lower rates of high blood pressure and diabetes, and are less likely to smoke.  But here's the kicker: despite the fact that distance running unquestionably reduces your risk factors for coronary disease, it may not actually reduce the chances of developing coronary disease.

CT scan reveals calcification of the coronary arteries.
One of the problems with standard screening tests for coronary artery disease--namely, EKGs and stress tests--is that they are not particularly sensitive in detecting underlying coronary disease among fit individuals.  A routine exercise stress test aims to induce strain on the heart by gradually increasing the heart rate via exertion in a laboratory setting; patients are then assessed for symptoms of heart disease, or changes in blood pressure or heart monitor patterns.  For regular endurance exercisers, the limitations of this test are obvious.  If an athlete is increasing their heart rate via exercise on a daily basis without adverse symptoms, why would any abnormalities appear when she does it on a treadmill, in front of a physician?  However, in the past decade advances in technology have made high-resolution CT scanning widely available for the detection of underlying coronary artery disease.  A CT scan is not without downside--it does involve exposure to ionizing radiation, which is carcinogenic in high doses--but this modality can help identify at-risk individuals who might otherwise be missed by more traditional assessments of cardiovascular health.

Applying this test to an athletic population, researchers have discovered some surprising findings.  Despite having a lower incidence of hypertension, diabetes, and obesity, long-term marathon and ultramarathon runners actually have a higher incidence of coronary artery calcification than non-exercisers in the general population.  (Interestingly, runners who regularly train and compete at shorter distances do not demonstrate this finding.)  This paradoxical relationship has been reported as early as 2008, and has been validated several times since (including by yours truly and colleagues earlier this year).

Why does this happen?  We're not really sure, though several theories have been advanced that might account for this process.  One idea is that repeated high-intensity aerobic efforts subject the coronary vessels to more turbulent blood flow, which over time can lead to chronic inflammation and calcification.  Free radical formation, causing chronic oxidative stress, may also play a role. 

So, does this mean we should all stop running ultras?  Not necessarily.  No one has demonstrated as yet that this increase in coronary calcification leads to an increase in clinical signs of heart disease, or to an increase in mortality (we'll address this further in a subsequent post).  There is some thinking that the calcifications commonly seen in long-term distance runners are firmer and more stable than the softer plaque often seen in the general population, and therefore less likely to break apart and cause the downstream problems I talked about earlier.  Also, research demonstrates that long-term training leads to larger coronary arteries, with more ability to dilate (open up) than those in untrained subjects.  This might serve to counteract the narrowing effect of coronary calcification.  (If your hose is getting clogged, make the hose bigger, and water will be able to flow through more easily.)

OK, this isn't the most reassuring post of all time.  But let's sum up with what we actually know:

  • long-term endurance exercise reduces your risk of high blood pressure, diabetes, high cholesterol, and obesity.  Since heart disease is only one of the issues that can arise in people who suffer from these ailments, this fact alone is probably reason enough to keep training.
  • despite this, people who regularly train for and participate in marathons and ultramarathons appear to have a higher rate of coronary calcification than those who don't.  
  • this higher incidence of calcification may or may not be clinically relevant.  But all things being equal, you'd rather it wasn't there.
  • even runners with higher levels of coronary calcifications may not show signs or symptoms of disease, and standard screening tests may not pick up underlying disease in these people.
Therefore, my take-home point is not that we should all freak out and stop running.  But we should realize that we're not immune to coronary artery disease, even though we are invariably "healthier," on average, than non-runners.  For those of us entering our masters running careers, and who have been at this for several years or more, we should be cognizant of this risk.  Talk to your physician about the pluses and minuses of a CT scan of the coronary arteries, particularly if you have a family history of coronary artery disease in a close relative.  And check back next week when I'll tackle the "running versus mortality" question and try to debunk some of the negative press coverage you may have seen recently.


  1. As a sign of gratitude for how my wife was saved from Ischemic Heart Disease, i decided to reach out to those still suffering from this.
    My wife suffered Ischemic Heart Disease in the year 2013 and it was really tough and heartbreaking for me because she was my all and the symptoms were terrible, she always complain of shortness of breath, and she always have swelling in her abdomen . we tried various therapies prescribed by our neurologist but none could cure her. I searched for a cure and i saw a testimony by someone who was cured and so many other with similar body problem, and he left the contact of the doctor who had the cure to Ischemic Heart Disease . I never imagined Ischemic Heart Disease. has a natural cure not until i contacted him and he assured me my wife will be fine. I got the herbal medication he recommended and my wife used it and in one months time she was fully okay even up till this moment she is so full of life.Ischemic Heart Disease . has a cure and it is a herbal cure contact the doctor for more info on on how to get the medication. Thanks admin for such an informative blog.



    I've been dating for almost 7 years until i contracted GENITAL HERPES VIRUS from my Ex-boyfriend who never told me he was having it.Ever since then i have been searching for cure everywhere because i was feeling so uncomfortable having so many outbreaks, Most people have herpes in one form or another, i was first taking Antiviral medicines such as acyclovir (Zovirax), famciclovir (Famvir), and valacyclovir (Valtrex), which are recommended for treating primary genital herpes outbreaks..But i needed to get rid of it completely, I came across so many testimonies online speaking about cure to herpes. i was so eager to be completely cured, I became a victim of fraud after contacting several so-called herbal doctors i was referred to. I lost a lot of money but i didn't stop searching for a cure.
    Then one faithful day,i came across a testimony of a lady saying that she got her Genital herpes cured by a GREAT HERBAL DOCTOR she called Dr. Aramide by contacting him through his email address. And she advised anyone with GENITAL HERPES or SIMPLEX HERPES to contact him for HERBAL CURE. I contemplated for about 4 hours whether or not to contact him. Then something inside of me told me to give a try. I then contacted him through his email and told my problems to him. He told me all the things I needed to do and also gave me instructions to follow, Which i did properly. Just within the 7 days of drinking and applying the herbal medication he sent to me through DHL delivery service, I started feeling changes in my body i went to my medical doctor for check-up, I was so happy when he told me i was no more having GENITAL HERPES VIRUS and that i was free, It was all tears of Joy from that moment, I never thought ROOTS & HERBS could cure HERPES and if i could ever meet a GENUINELY GREAT HERBAL DOCTOR. I'm so grateful to him. i am completely free from GENITAL HERPES VIRUS,i recommended him to a family friend having Simplex Herpes virus, He called me and told me he is also cured completely. I promised to share my own testimony like that of the lady on the internet. If you are also having
    *GENITAL & SIMPLEX HERPES... or need cure to diseases/viruses like..
    *ASTHMA.. Etc..
    Without Hesitation Contact him Today for a testimony through his Email _ & Website:

    For more info;
    Phone No: +1(786)581-7266


  3. I have been trying to get pregnant for over 5 years now. My husband and I
    have been seeing a fertility specialist. We have done our best but no luck.
    My husband has a sperm count which goes up and down,the doctor has
    recommended him taking the Proceed supplement which he is doing over 3
    years with no change in the situation .. I was so confused until i
    contacted this powerful spell caster Dr. Ebhota online who I saw a number
    of testimonies of how he has help so many of people so I sent Dr. Ebhota a
    mail and I told him all my sorrows and pain he replied me and ask me not to
    cry any more that he will help, he sent me some instructions and caution,
    Dr. Ebhota cast the spell and I bought some items to complete the spell
    casting and he told me to meet with my husband.. Within 3weeks of doing
    this I felt some changes and I went to my doctor and it was confirm that I
    was pregnant,i promises Dr Ebhota to share his testimony for three years,it has been over a year and four months now,i have been testifying this great testimonies for my life and my husband,for any one how need his help herb potion should contact him,on his Email [ ] or call him on [ +2349035324155 ]

  4. To cure herpes virus entirely and some other problem, you must understand what causes it, what worsen it and the exactly proven method of getting rid of it. I've been experience it for a long time however it is totally gone now...Check out the following web site for additional information: Dr.Sandy Herpes home on Facebook . Com* Yes Dr.Sandy herbal medicine do work... We gave my sister of his some of his herb (medicine) in 14 days the family doctor. told us how she was doing good. Hypertension his medicine are high but we can't put a price on your body all natural. Thank you Dr.Sandy .. 🙏🙏 you will be missed if you live us.yes I know they will try to kill this new herbal man because he is helping the world and cured thousands of people.....the new young king...and if ever they try to get you don i will still try all for your Legacy to go on.👼✊🙏 and he does a lot of spells such as...Herpes Cure ..ALS Cure..Hiv Cure..Love .Money Power ...Success .Sickness ..Pregnancy herbal medicine...Marriage ..Job ...Protection..Court Case Spell..Luck Spell etc contact his email address. OR
    call Whats App Number +2349031726182
    or facebook posg
    Share this plz friends so many people can know about him plz plz...

  5. This comment has been removed by the author.