Not Too Much and Not Too Hot

Life-Threatening Events During Endurance Sports: Is Heat Stroke More Prevalent Than Arrhythmic Death? In the Journal of the American College of Cardiology (2014) a study was done In Tel Aviv to determine if more life-threatening events during endurance sports were caused by heat stroke or directly related to events of the heart. Lior Yankelson MD PhD and his associates studied 137,580 long distance runners from March 2007 to November 2013.

Heat, Not Heart, More Likely Culprit When Runners Collapse. The Tel Aviv study was followed by a review in Medscape, calling attention to the significant role of heat rather than heart in fatal and nonfatal marathon events.

Neither Too Fast nor Too Hot: Keeping Marathoners Hearts Alive During the Race. Finally, two brilliant and respected Cardioloists, Brian Olshansky M.D. and David S. Cannom M.D., wrote an editorial for the the Journal of the American College of Cardiology (2014), commenting on the original Yankelson Tel Aviv study. They entitled their editorial to acknowledge both dangers — too fast (intensity) and too hot. For the 137,580 runners in the 14 Tel Aviv marathons between 2007 and 2013, there were two non-fatal cardiac events, two heat stroke fatalities and 19 heat stroke survivors. All were aggressively treated.

No Comparison. Severe overheating can cause multiple organ failure during a race; but for those who repeatedly run the intense marathons, the heart itself can kill at any time and irrespective of the temperature. Life-ending arrhythmias due to electrophysiological and anatomical remodeling of the myocardium secondary to repeated and intense cardiac overload and stretching over time provides the mechanism. And that death need not be while actually participating in a marathon, as in the Tel Aviv study. Thus, the comparison of life-ending, overheated, multiple organ failure to arrhythmogenic death during the race is not meaningful. Although, certainly, too much overheating of body organs is in itself significant and alarming.

Marathon runners, triathletes, and Strong Man participants who overload and stretch the muscle fibers in their heart chambers with the demands their sport makes for more and more cardiac output to supply the oxygen hunger of their hard working skeletal muscles, should not be misled by the title of the article, "Heat Not Heart", nor should they feel empowered by an over simplistic, normal stress test. The athlete's history counts!


Yankelson L, Sadeh B, Gershovitz L, et al: Life-threatenng events during endurance sports: Is heat stroke more prevalent than arrhythmic death? J Am Coll Cardiol 2014; 64:463-469.

Michael O'Riordan (a senior journalist for and a Medscape Cardiology journalist), Heat, Not Heart, More Likely Culprit When Runners Collapse, July 29, 2014

O'Keefe JH, Patil HR, McCullough PA: Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise http://www.mayoclinicproceedings, Jun 2012;87(6):587-595

Olshansky B, Cannom DS: Neither too fast nor too hot: Keeping Marathoners' hearts alive during the race. J Am Coll Cardiol 2014; 64:470. Ed

Mary Boudreau Conover mc/8/15/2014