Is marathoning too much of a good thing for your heart?

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seuss
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Is marathoning too much of a good thing for your heart?

Postby seuss » Fri Dec 08, 2006 3:29 am

From the NY Times:

http://www.nytimes.com/2006/12/07/fashi ... 0Kl27ivTdg


Abstract of the study report:

Circulation. 2006 Nov 28;114(22):2325-33. Epub 2006 Nov 13.

Myocardial injury and ventricular dysfunction related to training levels among nonelite participants in the Boston marathon.

Neilan TG, Januzzi JL, Lee-Lewandrowski E, Ton-Nu TT, Yoerger DM, Jassal DS, Lewandrowski KB, Siegel AJ, Marshall JE, Douglas PS, Lawlor D, Picard MH, Wood MJ.

Cardiac Ultrasound Laboratory, Division of Cardiology, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02115-2696, USA.

BACKGROUND: Multiple studies have individually documented cardiac dysfunction and biochemical evidence of cardiac injury after endurance sports; however, convincing associations between the two are lacking. We aimed to determine the associations between the observed transient cardiac dysfunction and biochemical evidence of cardiac injury in amateur participants in endurance sports and to elicit the risk factors for the observed injury and dysfunction.

METHODS AND RESULTS: We screened 60 nonelite participants, before and after the 2004 and 2005 Boston Marathons, with echocardiography and serum biomarkers. Echocardiography included conventional measures as well as tissue Doppler-derived strain and strain rate imaging. Biomarkers included cardiac troponin T (cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP). All subjects completed the race. Echocardiographic abnormalities after the race included altered diastolic filling, increased pulmonary pressures and right ventricular dimensions, and decreased right ventricular systolic function. At baseline, all had unmeasurable troponin. After the race, > 60% of participants
had increased cTnT > 99th percentile of normal (> 0.01 ng/mL), whereas 40% had a cTnT level at or above the decision limit for acute myocardial necrosis (> or = 0.03 ng/mL). After the race, NT-proBNP concentrations increased from 63 (interquartile range [IQR] 21 to 81) pg/mL to 131 (IQR 82 to 193) pg/mL (P<0.001). The increase in biomarkers correlated with post-race diastolic dysfunction, increased pulmonary pressures, and right ventricular dysfunction (right ventricular mid strain, r=-0.70, P<0.001) and inversely with training mileage (r=-0.71, P<0.001). Compared with athletes training > 45 miles/wk, athletes who trained < or = 35 miles/wk demonstrated increased pulmonary pressures, right ventricular dysfunction (mid strain 16+/-5% versus 25+/-4%, P<0.001), myocyte injury (cTnT 0.09 versus < 0.01 ng/mL, P<0.001), and stress (NT-proBNP 182 versus 106 pg/mL, P<0.001).

CONCLUSIONS: Completion of a marathon is associated with correlative biochemical and echocardiographic evidence of cardiac dysfunction and injury, and this risk is increased in those participants with less training.
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Robert
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Postby Robert » Fri Dec 08, 2006 8:14 am

It's an interesting study for sure, but there may be more to it than meets the eye. There was also a very useful editorial written about that paper in the same issue of Circulation. The entire aricle and the editorial are available by subsription only, but if anyone wants copies I can email you PDFs of both. The jury is probably still out on whether marathon running is detrimental.

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garth
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Postby garth » Fri Dec 08, 2006 8:43 am

This would make sense. The heart is a muscle.

Stress it and it is going to show the effects of that stress in any testing. The degree of effect is also going to be relative to the length of time the stress is applied and the condition of the muscle before it is stressed.

Like to see the same test on a olympic vs casual weigth lifter on other muscles in the body.
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RayMan
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Postby RayMan » Fri Dec 08, 2006 8:50 am

Isn't 60 people way too small of a group for a study like this? What I recall of statistics is that 1000 people are needed to really make any broad statements like this study does...

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Jwolf
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Postby Jwolf » Fri Dec 08, 2006 9:45 am

It's no suprise that those who train less for a marathon will suffer more strain than those who train more. And recovery takes longer.

Other studies have shown other types of heart damage after a marathon. But none have shown any lasting effect.

Robert, I'd like those articles. I'll pm you with my email address.

(or just post the references, which one can get through a university library...)

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SunRunner
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Postby SunRunner » Fri Dec 08, 2006 12:05 pm

This is strange because I just had an Echocardiogram done yesterday. I have had one twice before. They had found something abnormal the first time, but not really clear what. I was told there was no problem with running. I am now wondering how close to running a marathon was my first test. I guess I should look into this more before I try to do another marathon.

Brad

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Robert
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Postby Robert » Fri Dec 08, 2006 1:24 pm

Jwolf wrote:It's no suprise that those who train less for a marathon will suffer more strain than those who train more. And recovery takes longer.

Other studies have shown other types of heart damage after a marathon. But none have shown any lasting effect.

Robert, I'd like those articles. I'll pm you with my email address.

(or just post the references, which one can get through a university library...)


Circulation 2006 114: 2306 - 2308
Circulation 2006 114: 2325 - 2333

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dwayne_runs_far
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Postby dwayne_runs_far » Fri Dec 08, 2006 1:58 pm

Those who had run less than 35 miles a week leading up to the race had the highest troponin levels and the most pronounced changes in heart rhythm


This is one of the more interesting bits that I took away from the article. I think, given that the heart is a muscle as well, that in my experience, the more miles I've been doing, the less recovery time I need for a substantial effort as I'm going to be more conditioned. Of course there is always the increased risk of injury as mileage increases, but if it leads to a lower risk of sudden damage, then I'll go for the high miles.

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