Running, long considered a healthy hobby, may actually be dangerous for some. At least that’s the
prevailing opinion of a number of the country’s top cardiologists and a new
study due out next month from British journal Heart.
According to the editorial, endurance training and marathon
running can literally push your heart to its limit, causing a variety of acute
problems, such as arrhythmia or irregular heartbeat, and lasting damage,
including calcification and scarring.
Some of these problems are impossible to
predict, even if you’re an athlete who has been extensively pre-screened with
cardiac tests prior to training. For older athletes, the toll that running takes may even outweigh the benefits gained from exercise, the study claims.
For many, the new information doesn’t add up. Why, for
instance, would athletes who have been training for many years suddenly
experience heart trouble associated with running?
The answer is simple. Intense physical exercise for long
periods has the potential to take a toll on the body, in some cases aging it
According to James H. O’Keefe, M.D. of the Mid-America Heart
Institute of Kansas City, who co-authored an extensive 2012
study that examined the cardiac risks faced by athletes: “Physical
exercise, though not a drug, possesses many traits of a powerful pharmacologic
agent. A safe upper dose limit potentially exists, beyond which the adverse
effects of physical exercise, such as musculoskeletal trauma and cardiovascular
stress, may outweigh its benefits.”
In short, exercise is great in small doses, but too much
physical exertion too quickly or for too long a period can actually put a
person’s heart at risk, especially if he or she is over age 35.
Watch any marathon runner and it’s obvious that his or her
body is under a great deal of stress. Temperature increases significantly, causing
sweating, fluid loss, potential dehydration, muscle weakness, and even
disorientation. But now researchers also have an idea about how marathon racing
and long-term endurance training affects the heart muscle, too.
In the aforementioned 2012 Mayo Clinic study, for instance,
long-term endurance training was associated with “coronary artery
calcification, diastolic dysfunction, and large-artery wall stiffening.”
In that study, researchers associated endurance training
with temporary spikes in sustained inflammation that was, in some cases,
injurious to the heart muscle. That impairment may lead to permanent scarring
or ventricle damage, which was seen in 12 percent of cases, or more acute
issues like arrhythmia or sudden death, which is what killed runner Micah True
in 2012 during a training run in New Mexico.
According to the Cleveland
Clinic, sudden cardiac death occurs in about one of every 15,000 joggers
and one in every 50,000 runners; a 2008 study
in European Heart Journal equated the
greatest risk of sudden cardiac arrest in marathon runners with those who had
the least amount of training.
study presented at the Canadian Cardiovascular Congress echoed those same
findings. In that study, runners who were less fit (as assessed by V02 max
testing) had signs of “inflammation, swelling, and decreased perfusion accessed
by MRI over three months.” Those runners who were better trained over a longer
period were less likely to experience the same level of heart damage.
According to Carl J. Levine, M.D., Medical Director of
Cardiac Rehabilitation and Prevention at the Ochsner Medical Center in New
Orleans, anyone interested in marathon running should undergo cardiac
pre-screening tests to eliminate underlying heart conditions. As many as ten
different pre-existing cardiac conditions can be detected.
Levine recommends that physicians also take detailed
histories of their patients, especially those who are in training, to look for
evidence of overexertion, such as tendonitis, stress fractures, and other
O’Keefe, a cardiologist and co-author of the Mayo Clinic
study as well as a marathon runner himself, said it best: “Extreme exercise is
not conducive to great cardiovascular health. Beyond 30 to 60 minutes a day,
you reach a point of diminished returns.”