Running marathons has become a very popular activity in our country with over 540,000 people completing the 26.2 mile distance in 2013. The demographics of marathon runners have changed significantly over the past few decades. Whereas 90% of the 143,000 runners in 1980 were male, 43% of the 541,000 runners in the US in 2013 were women. Many marathon races are over 60% female. Runners are also getting older. In 2013, the average age for male runners was 40.2 years and for female runners was 36.6 years. It is no longer a race for the 20-30 year old man. Marathoners are also different from typical American demographics in other ways; about 60% of marathoners are married and 80% have college educations. As runners have increased in average age over the past three decades, the average time to complete the marathon has increased from 3:30 to 4:16 for men and from 4:03 to 4:42 for women.
Providing medical care for a marathon presents many challenges. No matter how many medical aid stations you have, you can never cover all 26 miles with medical personnel. Luckily most medical problems in a marathon are minor (muscle aches, sore feet, and muscle cramps), but some can be serious. It is not uncommon to have significant dehydration, heat stress, hypothermia, or cardiac issues in a marathon. In fact, it is possible to have hypothermic runners and heat stressed runners in the same race as marathons often begin on a chilly morning, but the ambient temperature may be over 65 degrees (hot for a marathoner) at the finish line 4-5 hours later. Most running injuries occur in the second half of the course with the majority arising in the last few miles.
Cardiac arrest is always our biggest fear but, luckily, cardiac arrest in marathoners is a rare event. There were 26 deaths among 3.3 million marathon runners (over 700 races and 14 million hours of marathon race running) in the US from 1975 to 2004. A more recent study in the New England Journal of Medicine documented 59 cardiac arrests in 10.9 million marathon and half-marathon runners, for a rate of one cardiac arrest in 259,000 runners. In young runners, the majority of arrests are due to hypertrophic cardiomyopathy, but in the older runner (people over 40) the major causes are ischemic heart disease or ventricular tachycardia. Most cardiac arrests happen at the finish line. Almost all are in men.
There have been many studies of heart health in marathon runners and some of the findings are very surprising. One study of men over 50 who had run at least five marathons showed they had the same coronary calcium scores as sedentary controls. Another study compared men who had each run 25 marathons to sedentary controls. The marathoners had lower weight, lower resting heart rates, lower blood pressure, lower lipids, higher HDLs, and no diabetes (compared to 17% for controls). However, the marathoners had significantly higher coronary calcium scores and, surprisingly, 52% were former smokers compared to 39% of controls. Framingham risk scores underestimate CAD risk scores, particularly in people who are overweight smokers, then get the idea to change their lives in middle age. Don’t let the low blood pressure, low LDL, and high HDL fool you – marathoners can have significant cardiac risk.
One piece of good news is that a person with a cardiac arrest during a marathon has a significantly higher survival chance than someone having a cardiac arrest almost anywhere else in the community. In most cases of cardiac arrest in marathons, there will be a doctor, paramedic, or nurse running the marathon nearby and most of the non-medical runners are college educated and likely know CPR. I volunteer as Medical Director of the Napa Valley Marathon, and we hand out small cards when our runners register that instruct runners on bystander CPR. We also have four AEDs from mile 24 to the finish line. We can never cover the whole race, but we try to position ourselves to have the best chance of a safe outcome for all runners.
James Cotter, MD