Fitness: There are many possible causes of marathoner deaths, cardiologist says – Montreal Gazette

Two half-marathons on the same day, one in Montreal and one in Ottawa, reported a runner collapsing at or near the finish line. Both runners were males in their 20s. Both died.

Sudden deaths during long distance events, such as marathons and half marathons, are rare. Yet they grab headlines, largely based on the paradox of a runner in top physical condition dying while exercising.

Just how frequently do marathoners collapse? And what can race directors and runners do to mitigate risk?

Several researchers have studied the phenomenon in hopes of gaining valuable insight. One of the first published studies reviewed 26 marathons across the U.S. over a 30-year period. Based on 3,292,268 runners, the overall risk was calculated as one death for every 126,626 finishers. The average age of the runners who died was 41. Eighty-one per cent of the fatalities were men.

A similar study published in 2012, this one including 10.9 million runners competing in 40 marathons and 19 half marathons, stated that the incidence of sudden death was 1.01 per 100,000 runners in the marathon versus 0.27 per 100,000 in the half marathon. Again, most of the victims were male and the average age of death was 39.

But age, gender and risk of death weren’t the only noteworthy statistics revealed by the researchers. Most runners collapse in the latter part of the race, with the majority of cardiac arrests occurring between the 37-kilometre mark and the end of the 42-kilometre distance.

As for the cause of death, cardiovascular disease is the most common reason the hearts of runners fail during an endurance event. No one knows exactly what triggers the event, but a common theory is that the stress of running a marathon initiates a release of inflammatory biomarkers that can increase the chances of cardiac arrest — especially in men over 40.

There’s also no consensus as to why this doesn’t occur in the weeks and months leading up to the marathon, when runners are putting in their training miles. It’s possible that the stress of race day may create a very specific set of conditions that adds additional strain on a diseased heart.

It’s worth noting that most marathoners don’t run the full 42-kilometre distance until the day of the race, with the majority of training programs taking runners up to about 30 kilometres, or three hours of running. As any marathoner can attest, those last 10k is when the body starts to feel the stress of a prolonged run at race pace.

But coronary heart disease isn’t the only cause of sudden death in marathoners. Hypertrophic cardiomyopathy, a structural abnormality characterized by a thickening of the heart that makes it harder to pump blood, is another cardiac condition that increases risk of sudden death during exercise. And while it’s rare, it’s often what fells younger marathoners who are running without knowledge of their condition.

It’s not known whether victims of sudden cardiac arrest experience any symptoms during training or the marathon itself.  And since symptoms like fatigue and shortness of breath can be the result of both physical exertion and a poorly functioning heart, they might not raise any red flags. Also, runners often consider themselves invincible, believing that anyone who can run for three hours or more has a healthy heart — which means they can often be dismissive of symptoms that seem incongruent with an active lifestyle.

There are other reasons for marathoners to collapse during a race. Hyponatremia, caused by excess fluid intake, is more common among women and slower runners. And while it can be fatal, educating runners to drink when thirsty versus ahead of their thirst is a relatively easy fix.

Heatstroke is another serious health issue runners face, though it is rarely a cause of death. Recent years have seen race organizers cancel races, modify start times to earlier in the day and provide more water stations and cooling stations along the route, in an attempt to cool runners during unusually warm marathon events.

This same commitment to running a safer event should be reflected in what we already know about sudden death during marathons and half marathons. Given the data indicating that most deaths occur within the last few kilometres of the race or immediately after crossing the finish line, medical interventions should be stationed along the course accordingly.

Rafik Tadros, a cardiologist from the Montreal Heart Institute who specializes in cardiac arrest, says thoughts of the finish line can result in a flood of adrenaline or a sudden surge in speed, both of which might trigger a heart arrhythmia causing cardiac arrest during the later stages of the race. However, he reminds runners that heart disease or structural abnormalities of the heart — not running a marathon — is the real cause of cardiac arrest on race day. He also suggests that more volunteers/individuals trained in CPR along with the strategic placement of defibrillators along the race route can make a difference in those crucial few minutes after a runner collapses.

Tadros says headlines about sudden deaths during marathons shouldn’t deter runners from taking on the challenge. The health risks of being inactive greatly outweigh those associated with running a marathon.

“Got for it, “ he said to all runners training to go the distance.