It may seem obvious at first: training for a marathon improves risk factors related to cardiovascular disease. But recent years have seen middle-aged male runners dying from cardiac arrest while running a marathon, suggesting older men are at higher risk while running the 26.2-mile race.
Now, research presented at the American College of Cardiology's 63rd Annual Scientific Session suggests training for the big race may be an effective strategy for reducing heart disease risks.
Because little is known about how heart health is affected by the marathon training process - which involves intense long-distance weekly running - researchers decided to study 45 recreational male runners between the ages of 35 and 65.
They were all planning to run the 2013 Boston Marathon as part of the Dana-Farber Marathon Challenge fundraising team.
"We chose charity runners because we wanted to focus on the non-elite type of runner, just the average average Joe who decides to get out there and train for a marathon," says Dr. Jody L. Zilinski, lead investigator from Massachusetts General Hospital.
Around half of the runners had previously run three or more marathons, and all participants were invited to participate in the training program, which lasted 18 weeks.
This involved group runs, endurance training, a detailed training guide, access to cross-training facilities in Boston, nutrition tips, pacing advice, and regular coaching contact. Depending on the training phase, the participants were instructed to run between 12 and 36 miles each week.
The researchers tracked the runners' adherence to the program through running logs the participants kept.
"They turned out to be a healthier population than we expected," says Dr. Zilinski, "with a lot of them already exercising on a pretty regular basis, but they were still nowhere near the levels of elite runners."
Further studies needed to see if reduced risks apply to women
Middle-aged men who participated in a marathon training program had reduced cardiovascular risks, research shows.
Before the training program began, the runners had a full medical evaluation performed on them, which included cardiopulmonary exercise stress testing, heart imaging studies and cholesterol screening.
Over 50% of them had at least one cardiovascular risk factor - including high cholesterol, high blood pressure or a family history of heart disease. Prior to running the marathon but after the training program, the researchers re-evaluated the health of the participants.
The team found that participation in the training program resulted in significant changes in cardiovascular risk factors.
In detail, low-density lipoprotein - known as "bad" cholesterol - was reduced by 5% and total cholesterol fell 4%. Meanwhile, triglycerides dropped by 15%.
Additionally, body mass index (BMI) dropped by 1%, and there was a 4% increase in oxygen consumption, which is a measurement of cardiorespiratory fitness and a factor indicative of cardiovascular mortality.
Dr. Zilinski says:
"Overall, participants experienced cardiac remodeling - improvements in the size, shape, structure and function of the heart. Even with a relatively healthy population that was not exercise naïve, our study participants still had overall improvements in key indices of heart health."
She adds that their findings emphasize how regular exercise can improve heart disease risk factors. However, she says individuals should first check with their doctor before beginning a rigorous training program.
The researchers say that as their research focused on a middle-age male population, their findings may not be applicable to other populations - female runners, for example.
Medical News Today recently reported on a study that suggested heart attacks and stroke at work are often preceded by vigorous activity.