Sudden Cardiac Death in Triathlon – Should Triathletes Be Concerned?

Every few years (or months?) an article comes out that galvanizes the public, throws the media into a frenzy and forces us to take a good look at actual risk. “Death and Cardiac Arrest in U.S. Triathlon Participants” by Harris et al., was that article for triathletes. Published just a few days ago it threw the triathlon community into disarray. The British Medical Journal and the article itself went as far as suggesting that sudden death during a triathlon was “not rare” in the first sentence of its publication about the article. But, should we be as afraid as they say? Is triathlon really killing us? Let’s take a deeper dive.

Firstly, let’s do our best to break down the percentage of deaths:

Segment All deaths Race Length Percentage Death
Swim 67% Sprint 54%
Bike 16% Intermediate 26%
Run 11% Long 21%
Post-Race 6% First Triathlon** 39%

** Data only available for 67 participants** (Harris et al., 2017)

Data Breakdown: So, let’s analyze what we actually have. Data were gathered from USAT – which let’s assume is accurate. I didn’t bother quoting the male vs female rate of the article because the main figure is more important. It is important to note that men are at much higher risk of dying than women. The main number that caught my eye is a large percentage of deaths occurred during the participants first race. Nearly half the participants that died were competing in their first race. Unfortunately, this data set is only available for 67 people. Would it be safe to assume USAT should have data on more if they’ve competed before? Did the other deaths that occurred happen during a first triathlon as well? Were the competitors simply undertrained or untrained? Perhaps. Perhaps not. Let’s file this away for the summary when we either tell people to never race again or take the article with a grain of salt.

Where the deaths occur: For triathletes, it should come as no surprise that the majority (70%) of the deaths occurred during the swim portion. It’s hectic, violent, and unnatural. I’m a bad swimmer so I’ll continue to push the agenda that humans aren’t meant to swim. Except, of course, Michael Phelps and Katie Ledecky. The hypothesized reasons are, as the article quite accurately mentions:

  • High adrenaline during the first few minutes can trigger heart issues (arrhythmias)
  • Anxiety attacks in the water for untrained racers causing aspiration, tachycardia and panic
  • Collisions, punches and kicks during the swim proliferating panic
  • The complexity of water rescue

Incidence: Should we be afraid? Let’s take a look at deaths during other activities and then compare the deaths to the general population. Deaths during a marathon (26.2 mile run) are 1 per 100,000 (Kim et al., 2012) slightly less than deaths during a triathlon 1.74 per 100,000 (Harris et al., 2017).

Now, let’s take a look at sudden cardiac deaths in the general population.



Phew! The number of men to women are similar. We can safely assume neither article jumbled the data in a freak accident. We can also safely assume that men aren’t crazier than women in triathlon as more men die from SCD than women, overall. There is no question regarding risk of dying of SCD as we age. Triathlon or otherwise, the natural physiologic progression of disease trends upwards as time goes on. To quote Fight Club “on a long enough timeline, the survival rate for everyone drops to zero”.

As we can see from the chart above, every single age group category death is exponentially higher than our triathlon article states. So we can assume that triathlon deaths when compared to the general population ARE rare, overall.

However, this is where the statistical fun begins. This is the annual rate. Using some statistical magic we can come up with a risk-adjusted background rate of approximately 0.5/100,000. When extrapolated, is about 1000 times less than the death rate during a race (the reason for this is rate of day vs rate of year or 0.5 vs 1.7 or 3×365)? Wow!

However, as with anything statistically related, it should be taken with a grain of salt. For one, it could mean that 1/100,000 have an undiagnosed medical condition which presents itself during a triathlon or it could mean that going out and doing something is more dangerous than sitting on your couch.

Let’s take some other incidence rates (in epidemiology, incidence is the probability of occurrence of a medical condition usually expressed as X per 1,000 or 100,000).

Let’s take a look at some other incidence rates:

Measure Rate
Killed by Asteroid 0.5/100,000
Cycling .65/100,000
Skydiving 1/100,000
Scuba diving 3/100,000
Canoeing 10/100,000
Car Accident Deaths 11.3/100,000


OK, that first one is a joke but you get my point

We clearly see that you have a significantly higher chance of dying while driving to a race than competing in one. Yet we drive daily to races or otherwise.


Summary: So should we be concerned? Personally, I don’t think so. But that doesn’t mean we shouldn’t take precautions. Physicals and cardiology visits become increasing more important as we age.

Although the Harris et al., article is missing data (first tri data were only available for 67 participants) and has significant limitations, it points out that first time triathletes are at higher risk and should consider consulting a physician before competing. First timers should properly train for any distance race and have at least ONE swim in open water (under supervised conditions).

All athletes should be aware of the warning signs, be prepared to race (which includes being comfortable to swim in open water) and be prepared to stop if necessary.

A proper diet to complement exercise is paramount. A significant portion (44%) of autopsies revealed cardiovascular abnormalities such as coronary artery disease. It is worth noting that regular exercise and death are not mutually exclusive. Regular exercise can slow the progression of heart disease but eating an unhealthy diet will eventually catch up to you as you simply cannot outrun a bad diet.

However, the point remains that sudden death during a triathlon or marathon is SUBSTANTIALLY lower than sudden death in the general population when not using advanced statistics as scare tactics.

Although we can argue whether or not we should be afraid of death during a triathlon, one thing is for certain, we cannot argue that triathlons are making us healthier, overall.