Ironic that only 24 hours after I posted "Is Too Much Exercise Bad For You?" that the Associated Press came out with an article "Triathlons Pose Deadly Heart Risks" . The media is swarming all over some recently released research studies, warning that triathlons cause a higher risk of a fatal heart attack than marathons. Obviously, this warrants a closer look.
First, the studies found that newbies (aka weekend warriors) were more at risk. This makes sense. Your body isn't used to the demands of your new training program. That's why doctors always recommend getting checked out before starting new exercise. Exercise is only good for the heart after several months of consistent, frequent training because it strengthens the heart. The heart is a muscle--aerobic exercise is like weight lifting for the heart. But just like doing bicep curls, you have to break down the muscle a little first before it builds back up and gets stronger. So to make your heart stronger, you have to stress it. Meaning that if you're new to triathlon or working out, and you have an underlying heart problem that hasn't given you symptoms yet because you've been a sedentary couch potato, and you suddenly start running 10 miles, the chance of your heart going "WTF?" and conking out is much higher.
Secondly, probelms usually occur at the very beginning of the triathlon, in the water. The shock of cold water constricts blood vessels, stressing the heart, not to mention all the adrenaline from the thrill right before the start of a race, causing the heart rate to skyrocket.
Finally, on a blog post by Dr. John Martinez at Coastal Wellness, he takes a closer look at the study:
"Do Triathletes Have a Higher Risk of Heart Attacks?"/
First, note that it's a "retrospective" study, meaning that the researchers tried to make sense of an occurrence after it's happened (usually not very meaningful on it's own but can lead to the design of future, better studies with hypothesis-driven questions).
Second, the study looked at "all deaths" not just cardiac-involved ones. Of the 14 deaths included, 1 occurred due to a bike accident, and autopsies were only performed on 6 of the others. Of these 6, 4 showed signs of underlying heart disease. Since I study heart disease, I wonder how many of these patients with heart disease were age-related. I highly doubt triathlon caused the heart disease. As a matter of fact, triathlon (or any exercise) can delay or reverse the damage caused by heart disease (usually caused by sedentary lifestyle and poor diet resulting in high blood pressure, triglyceride and cholesterol). Second, there is no evidence the deaths occurred because of heart problems (heart disease can be asymptomatic for a long time).
Dr. Martinez says,
"However, the reality is that these individuals that did have cardiac events during the triathlon probably had significant cardiac disease despite their triathlon lifestyle..."
--and I have to concur.
Here's a great article
that looks at the cause of cardiac-related deaths during exercise:
"Exercise-associated acute cardiac events generally occur in individuals with structural cardiac disease."
Here's another article
taking a look at the risk/benefits of marathon training: