Monday, March 13, 2017

Running and Your Heart, Part I's been an interesting couple of months.  I think I've mentioned this before, but since late last year I've been involved with the Heart Center, the preeminent cardiology group in the Hudson Valley, in establishing a new sports cardiology practice.  I'm not a cardiologist (which will become eminently obvious over the course of the next couple of posts) but I have more than a layman's understanding of the athlete's heart and many of the cardiac issues that endurance athletes deal with.  Plus, I've always had a major interest in exercise physiology, and have been looking for an opportunity to break into that field for some time.  Starting within the next couple of months, we'll be opening the doors on our new sports cardiology practice (spiffy title pending) and I'll be working part-time as the group's exercise physiologist.  So exercise science and the athlete's heart have been on my mind quite a bit recently.

This was obviously at the forefront of my thoughts during and after Rocky Raccoon.  As a brief recap, I was running very well at Rocky through 60 miles (9:12) and, despite a nosebleed and some other minor issues, was still on pace for a top-6, sub-16 hour finish through 80 miles (12:45).  In the last twenty miles, however, I developed some rather scary breathing issues, including some rattling breath sounds starting around mile 88 that had me concerned I might be developing pulmonary edema.  Pulmonary edema is basically fluid buildup in the lungs; it can occur for a variety of reasons in sick or elderly individuals, but is much less common in young, healthy folks.  (I'm referring to fluid within the lungs; this is different from a pleural effusion, or fluid around the lungs, which is an entirely different issue I'm not going to address here.)  Mountain climbers can experience high-altitude pulmonary edema (HAPE), which is basically a failure of the pulmonary (lung) vasculature (blood vessels) in response to the physiologic demands of altitude--obviously not an issue in Huntsville, TX.

The most common reasons for a buildup of fluid in the lungs are basically an inability to remove fluid (kidney failure) or an inability to circulate fluid (heart failure).  Reports of kidney failure following extreme endurance events, due to a condition called rhabdomyolysis, are not uncommon.  Rhabdomyolysis occurs as a result of extreme muscle breakdown, when large amounts of a muscle-based proteins myoglobin and creatine phosphokinase (CPK) are released into the bloodstream.  Without proper fluid intake, these proteins can accumulate in the renal tubular system, causing kidney failure.  Kidney failure can lead to anuria (inability to urinate) and pulmonary edema, as the body cannot excrete excess fluid and hydrostatic pressure causes fluid to leak into the lungs and other tissues.  In a 100-mile race, this is certainly a possibility (though remote).  However, I wasn't terribly concerned; I had urinated several times during the race, without any blood (a telltale sign of muscle breakdown called myoglobinuria), I had been taking in adequate fluids, and it was not an overly warm day.  Also, rhabdo-induced renal failure is usually a later finding; it was hard to believe that my kidneys could have already failed to the point where I was going into pulmonary edema less that fourteen hours into the event.  My real fear was my heart.

The most common cause of pulmonary edema is heart failure.  Basically, if the heart muscle is weakened (by any of a variety of mechanisms; most commonly, a heart attack), its ability to pump blood adequately can be compromised.  This can lead to a backup of blood flow throughout the body. When the blood does not flow adequately through the venous system, that can cause an increase in the amount of pressure within the veins.  That increased pressure can cause fluid to leak out of the veins, where it doesn't belong--including into the lungs.

Fortunately, not my chest X-ray
Now, I had no real reason to be concerned about my heart.  Other than some mild hypertension, I have no personal history of heart disease, and no other significant risk factors; I had even undergone a recent CT angiogram of the coronary vessels (more on this in subsequent postings), which was normal.  But as I mentioned, I've been rather immersed in sports cardiology and the athlete's heart recently, and as I'll talk about in the next few posts, there are a lot of unlikely but unpleasant possibilities that can befall those of us who take this running thing a bit too seriously.  At its essence, the heart is a rather simple pump, but the underlying components of the organ are a bit more complex, and therein lies a lot of potential problems.  The relationship between exercise, heart health, and heart pathology is actually quite fascinating, and I'll explore that a little more as promised in coming posts. But certainly in real time I was less fascinated and more, well, freaked out.

Anyway, I finished the race by walking the vast majority of the last 18 miles or so, and since then have recovered more or less normally.  I had the usual post-race leg swelling, which in this case brought on some additional anxiety but ultimately resolved as expected.  For a few days afterwards I felt as though I was getting short of breath just walking around or climbing stairs, but I think that may have all been in my head.  A week later I went for an echocardiogram, which is an ultrasound of the heart.  This test shows the activity of the heart muscle in real time; it can show if there are areas of the muscle which are not functioning normally (wall motion abnormalities), if there are problems with leaky heart valves, and how much blood the heart pumps with each beat (ejection fraction).  My cardiologist said my heart was very photogenic:

He also told me that, other than some normal findings associated with the athlete's heart, everything looked good, and that my ejection fraction was normal.  And after a two-week break, I started running slowly again.  It's been a longish recovery period, but now five weeks post-Rocky I'm running more or less normal mileage and feeling just about ready to get back to some harder training again.  (Though the estimated 24" of snow coming our way tomorrow may preclude that for a little while.)

So, apparently this has all been much ado about nothing, fortunately, though it's forced me to think a bit about the role of the sport in my life.  It's a silly pursuit, of course, for those of us who are not making a living at it; sure, it's better than plenty of other bad habits we could have, but there probably isn't anything in our lives that needs to be taken to the extremes that we ultrarunners face regularly.  I did have some fleeting thoughts about what life would look like without 110-mile training weeks.  Unfortunately I don't think I'm mature enough to make any difficult decisions about it at this point, though with a clean bill of health it doesn't seem I'll be forced to do so for awhile.  So for now I'll keep plugging away and trying to slay whatever dragons strike my fancy in the coming months.  (Plus there's always the Western States lottery to look forward to.)

However, there's an awful lot of information out there regarding distance running and long-term health, and a lot of it can be very confusing.  So in the next few weeks I thought I'd try to demystify some of that information, in case anyone else is struggling with some of these decisions regarding their future in the sport.  Next post we'll talk a little bit about the athlete's heart and some of the various changes related to distance running, and whether or not we need to worry about those things.  After that we'll go into the association between ultrarunning and coronary artery disease.  And I'd like to spend a post on the relationship between strenuous exercise and overall mortality, which has been in the news quite a bit recently.  So, check back soon for more possibly accurate, semi-scientific information.