Risk of clots in marathon runners who travel by air

You have probably heard, at some point, that traveling on an airplane raises your risk of having a clot form in your leg veins. This is a complex phenomenon which may relate to a variety of things that occur during air travel including immobility (blood sitting still tends to clot), lower air pressure, and lower oxygen concentrations (both have been implicated in activating the clotting cascade in the body).

Now, in the March 2011 issue of the Clinical Journal of Sports Medicine, Parker et al. took blood samples from two groups of Boston Marathon runners, those who flew (over 4 hours) to the race, and those who drove (less than 2 hours) to the race. Three sample were taken, before the race, at the finish, and one day later, prior to returning home. In these samples, they measured different compounds which are known to play important roles in the formation of clots. The researchers found that from pre to post race, these compounds increased in both groups, but more so in the air travel group. They conclude that marathon running induces a hyper-coagulable state, presumably more so in those who travel by air. The study is interesting, but it was only conducted in 41 people and it does not measure actual clots, just blood tests that are markers for clotting.

While people do get vein clots while traveling by plane, they also occur during car trips and even seemingly without provocation. Other factors that increase your risk include birth control pills, age, and poor circulation from other medical conditions. Many people also carry minor deficiencies of anticlotting blood proteins, and many do not know they have them (Protein S or C deficiency and Factor V Leiden mutation). Dehydration also does not help, and that may be an additional concern for runners (also airplane air is very dry, about 20% humidity). Compression hose may help and staying hydrated while avoiding alcohol seem like good suggestions even if evidence of effectiveness is limited.

Crossposted at nevernotrunning.com

Cardiac Concerns in Marathon Runners

Cross posted from nevernotrunning.com
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Last week I gave a lecture for the Division of Cardiology at UF on the "Cardiac Concerns of Marathon Runners". The topic seemed a natural fit for me and I think most know that it is much easier to give a quality talk about a topic that you are interested in. I started my research for the talk by searching PubMed, which is the National Library of Medicine's web interface to access their database of medical literature. For medical research, it is basically the standard place to start a high quality search on any given subject in medicine. From there I branched out into searching for articles on marathon running in several prominent sports medicine, general medicine, and cardiology journals.

After collecting dozens of articles, I separated them into three general groups/topics around which I built my talk. First, the cardiologist perspective on pre-participation screening. Anyone who did sports in high school likely remembers having to get a doctor to clear you to participate. Well, grown-ups, especially those starting a new exercise program should do the same and there are some specific guidelines about what kinds of questions your doctor should ask and maybe a few tests that she/he should order for you.

Second, I talked about the adaptation to endurance sports. There are a lot of changes that go on in the body to make you better at your chosen sport. For cardiologists, one of the most important is the fact that your heart (a muscle) tries to grow stronger as you challenge it more and more. This means your heart may change size and shape. Now, this part is normal, but what is sometimes very challenging is for cardiologists to know the difference between your heart changing shape because you are an athlete, or your heart changing shape because you have some type of dangerous heart condition (ie: cardiomyopathy). In my talk I cover some of the important ways to tell the difference.

Third, I talked about the risks of being a runner, especially when you are out running. There are a lot of blood tests and imaging tests of the heart that show that during a run, some strange things can go on with the heart. The important part is that no one has yet shown that these strange things are actually dangerous. That said, there are some very real dangers, like the risk of arrhythmias, heart attacks, and sudden death while out running. Clearly, tragic incidents like that of Ryan Shay should make it clear that there are some risks to endurance sports, but the good news (to very briefly summarize) is that the higher risk of having a problem during a run  is far outstripped by the dramatic benefit you get from being a runner (ie: preventing heart attacks, preventing disability, and on average living longer.)

At some point I'll try and delve more into the details of my talk, but in the meantime, Happy Holidays!

American Heart Association 5K Fun Run

As part of setting a good example, the AHA conference this year held it's 18th annual 5K Fun Run. Several hundred doctors, nurses, and scientists came out at 6:30 AM in 37 degree weather to run up and down Lakeshore in Chicago. Many people also participated in the simultaneous 1 mile Fun Walk. The following is a cross-post of my race report from nevernotrunning.com.

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Tuesday November 16 at 6:30 was the AHA's 5K Fun Run, my first at this conference. Had a great time, weather was gorgeous (37F and a little warmer when the sun came up). Despite this just being a fun run as part of a large conference of doctors, nurses, and scientists, they did a great job with official timing tags, and a well done course. It wasn't shut down to the public since it was only a few hundred people, but not crowded in the slightest (thanks to the early start).

I have been under the weather for several days so I didn't know quite what to expect when I got out there. I had hit up a few puffs of albuterol before leaving the hotel, but left the inhaler there. It was a 2 mile run/walk/warmup from my hotel to the start which I was handling fine.

I was near the start and the 20 or so people in front of me quickly set out at a pace I could not possibly match, so I settled in and ran roughly 6:00, 6:30, and 6:30 with a finish of 19:03-ish. Believe it or not, this was my first officially timed 5K, so hooray, new PR for me! (age grade performance of about 68%)

Shortly after, I wished I had brought the inhaler because I started coughing violently due to the heavy breathing and cold air. But with another cup of coffee and some short, methodical breathing, I was able to keep the coughing at bay long enough to get back the 2 miles to the hotel and get a few more puffs.

I must recognize that this race was a memorial for Ken Baughman. One year ago at the AHA meeting in Orlando, FL, Dr. Baughman was out running when, at the intersection of Sand Lake Road and Universal Blvd, he was struck by a car and died. People who knew him wore shirts for "Team Baughman" and we shared a moment of silence for him prior to the race. Thoughts and best wishes to his family and friends for their tragic and unnecessary loss.


View American Heart 5K 2010 in a larger map

Lab tests are not all the same

Cross-posted from http://www.nevernotrunning.com

TIME Healthland posted an article on Oct 25 regurgitating the results of yet another study which "discovered" that after marathons, the same lab test that goes up in a heart attack (troponin) goes up after running 26.2. While I am sure the scientists reporting the study results did a fine job, the reporting could use some work. First, there are literally dozens of studies that have already shown this. Second, no one that I am aware of has shown that the increased troponin in marathon runners means a damn thing. For example, if your troponin goes up after a marathon, are you going to die sooner? Have a heart attack or suddenly die during a race? Those are the important things, not that your lab test is abnormal.

Lots of things can make your troponin go up, like getting in a car wreck and crushing your chest against the steering wheel. Or getting an infection on your heart valves. Or having a viral infection. Why aren't we comparing marathon running to these things? There is a lab test called the GGT. It is a marker of liver function. If you go out on a bender and have a half a bottle of tequila, your GGT will go up. Your GGT will also go up if you catch hepatitis, or have liver flukes, or eat magic mushrooms, or OD on acetaminophen. Now, is anyone out there saying that drinking tequila is the same as all these things?

It is certainly possible that endurance sports are doing something unsavory to the cardiovascular system, but at the present time, I am not aware of any such evidence and until you have something convincing, I wish the media would stop trying to scare people away from running, when all the available evidence points to it being healthy!

Reduced disability and mortality among aging runners

Here's another cross-post from nevernotrunning.com
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Steve Runner at Phedippidations covered a great article in Episode 245 of his podcast. I could have sworn that I blogged about this in the past, but I guess I forgot at some point, so let me remedy that with this recap.

Researchers at Stanford designed a study to assess the notion that older runners would experience more disability than older non-runners due to orthopedic injuries, etc. They found a few hundred runners and non-runners and tried to match them for baseline characteristics such as age, gender, medical history, etc. Then they followed them for an astonishing 21 years! Each year asking them about injuries and disability. Many subjects died during the follow-up period, but the important findings are:

1. Both runners and nonrunners died, but fewer runners (15% vs. 34%) died during 21 years of follow-up
2. Runners had less cardiovascular death, but also less cancer death and dementia
3. Runners had less average disability than nonrunners and the gap widened as subjects got into their 80's
4. On average, runners experienced the onset of disability several years after nonrunners!

The authors admit that studies like this are subject to "self-selection" bias, which means that being a runner was not a randomized variable. This means that people who are runners might be more likely to engage in other healthy activities that the authors could not account for (wearing a seatbelt, eating fruits and vegetables, etc.) While bias MAY affect the results, this data fits with existing literature suggesting morbidity and mortality benefits of regular exercise. 

The authors summarize their findings by describing this phenomenon as the "compression of morbidity", ie: everyone dies eventually, but runners spend a shorter period of their life disabled and unable to care for themselves. 

Listen to more with Steve at: http://steverunner.blogspot.com/2010/09/fdip245-life-should-be-long-enough.html

http://www.ncbi.nlm.nih.gov/pubmed/18695077

1. Arch Intern Med. 2008 Aug 11;168(15):1638-46.

Reduced disability and mortality among aging runners: a 21-year longitudinal
study.

Chakravarty EF, Hubert HB, Lingala VB, Fries JF.

Division of Immunology and Rheumatology, Stanford University School of Medicine,
Stanford, California, USA. echakravarty@stanford.edu

BACKGROUND: Exercise has been shown to improve many health outcomes and
well-being of people of all ages. Long-term studies in older adults are needed to
confirm disability and survival benefits of exercise. METHODS: Annual
self-administered questionnaires were sent to 538 members of a nationwide running
club and 423 healthy controls from northern California who were 50 years and
older beginning in 1984. Data included running and exercise frequency, body mass
index, and disability assessed by the Health Assessment Questionnaire Disability
Index (HAQ-DI; scored from 0 [no difficulty] to 3 [unable to perform]) through
2005. A total of 284 runners and 156 controls completed the 21-year follow-up.
Causes of death through 2003 were ascertained using the National Death Index.
Multivariate regression techniques compared groups on disability and mortality.
RESULTS: At baseline, runners were younger, leaner, and less likely to smoke
compared with controls. The mean (SD) HAQ-DI score was higher for controls than
for runners at all time points and increased with age in both groups, but to a
lesser degree in runners (0.17 [0.34]) than in controls (0.36 [0.55]) (P < .001).
Multivariate analyses showed that runners had a significantly lower risk of an
HAQ-DI score of 0.5 (hazard ratio, 0.62; 95% confidence interval, 0.46-0.84). At
19 years, 15% of runners had died compared with 34% of controls. After adjustment
for covariates, runners demonstrated a survival benefit (hazard ratio, 0.61; 95%
confidence interval, 0.45-0.82). Disability and survival curves continued to
diverge between groups after the 21-year follow-up as participants approached
their ninth decade of life. CONCLUSION: Vigorous exercise (running) at middle and
older ages is associated with reduced disability in later life and a notable
survival advantage.


PMID: 18695077 [PubMed - indexed for MEDLINE]

Getting started on an exercise regimen

Published online in the European Society of Cardiology is a great summary document for doctors, but potentially readable for patients, of how to get started on aerobic exercise when you have heart disease.

Firstly, they summarize a very important observation which can seem paradoxical. While exercise readily and dramatically lowers the risk of cardiovascular events, the act of going out for strenuous exercise (ie: running) TEMPORARILY slightly raises the risk. This is because patients with heart disease (silent or not) have two problems. Their hearts are a setup for lethal arrhythmias (ventricular tachycardia) and rupture of a coronary plaque (causing a heart attack). The risk of both of these is increased due to more adrenaline circulating in the blood and the greater blood flow across plaques. So while the risk of having an event DURING a run is increased, the overall risk is still very low, about 1 in 200,000 patient-hours of exercise (ie: 200,000 patients exercising for an hour each, or one person exercising for 200,000 hours, talk about a long run!) For comparison, being out of shape puts you at a 4.5 fold risk of death as compared to someone who is physically fit. Not to mention, being active may reduce your risk of diabetes, high blood pressure, and metabolic syndrome by up to 25%.

They recommend a variety of tests prior to starting exercise, such as an electrocardiogram (ECG), echocardiogram (echo), and treadmill stress testing. Each of these is meant to assess the fitness of the cardiovascular system. They also recommend examination of the lungs (pulmonary testing) and joints, since many people fail to stick with exercise due to being short of breath or knee/hip/foot/other pains. The authors also provide a handy chart for putting people into low, medium, and high risk categories based on how all the tests come out. Figure 1 from their paper shows part of why aerobic exercise is so important for cardiovascular health. Stroke volume, or the amount of blood pumped with every heartbeat, goes up dramatically with dynamic exercise (ie: running) but barely moves with isometric exercise (ie: lifting weights).

In terms of what they recommend for exercise, they note that anyone who has had a heart attack or other significant heart disease should ideally first go through a supervised program of cardiac rehab before starting exercise on their own. They recommend that for people doing exercise for "primary prevention" (ie: never had a heart attack), or only have high blood pressure (hypertension), it is fine to go ahead as long as the previously mentioned testing is normal.

So, no excuses, get out there and get started walking, running, or whatever!

Also, see this page on exercise from the medical journal Circulation which is written for patients.

This post also can be found on my running blog: www.nevernotrunning.com.

The Runner's Round Table: Running for a Healthy Heart

I'm cross-posting this from my nevernotrunning.com blog. I spent an hour with fellow runner's talking about heart heath and running on a podcast called the Runner's Round Table.

Just a reminder...

*DISCLAIMER* All material discussed herein and on the Runner's Round Table is discussed in generalities. None of this is medical advice and you MUST seek YOUR physician's counsel prior to undertaking athletic activity, especially if you have known cardiac disease.

For those that listened, I've got some notes here on things I mentioned:

• Each increase in MET you can tolerate is associated with a 12% increase in survival. Men whose maximal exertion was < 5 METs had a 4 fold higher risk of death than men who could achieve > 10.7 METs. (Morrow Circulation 2010;121:2681)
• The average person who is active, doesn't smoke, eats fruits and veggies, and doesn't drink to excess will live an average of 12 years longer than someone who does not do any of those healthy activities. (Kvaavik Arch Int Med 2010;170(11):998)
• About 30% of your risk of death comes from your genes. (Perls, Ann Int Med 2003;139:445) Another similar estimate shows that 90% of stroke risk comes from 10 risk factors, many of which are modifiable by lifestyle or medicine. (O'Donnell et al. Lancet 2010;376:9735)
• The Government Accountability Office recently reviewed the current state of direct-to-consumer marketed genetic testing.
• Air pollution increases the risk of cardiovascular disease. (Brook et al. Circulation 2010;121:2331)

We didn't get to talk about everything I thought that people might find interesting, like:

• People with heart transplants have run marathons! A worldwide organization similar to the Olympics which helps transplant patients compete in sports. Read about athletes like Ernesto Antonio, heart transplant recipient and finisher of the Dublin Marathon.
• People who have heart conditions should get cardiac rehab, which can have an incredible impact on improving your fitness. 3-6 months of supervised activity can increase aerobic capacity (VO2) by 11-35%!

Other References:

ACC Guidelines on Secondary Prevention of Cardiovascular Disease:

http://www.ncbi.nlm.nih.gov/pubmed/16697342

AHA Guidelines on Cardiac Rehab:

http://www.ncbi/nlm.nih.gov/pubmed/15668354

http://circ.ahajournals.org/cgi/content/full/111/3/369