Researchers in the making
Pushing the Limits
Ph.D. candidate Myra Cocker studies the cardiac health of elite athletes.
Story by Julie Sedivy/Photos by Trudie Lee
To many Canadians, the athletes who stepped up to the podium in Vancouver this past winter represented the pinnacle of physical health. It's hard to think of Olympic cross-country skiers and long-track speedskaters as poster children for heart disease; however, Ph.D. candidate Myra Cocker believes that high-performance training for endurance sports carries some risks that are worth taking seriously. Young athletes, for example, are much more likely than non-athletes of the same age to die suddenly of cardiac failure without prior symptoms. A fatal collapse during or right after strenuous exercise is often the first sign of any heart problems. In 2009, 41-year-old Calgarian Richard Black died of cardiac failure after completing the annual 10-kilometre Melissa's Road Race in Banff. The contributing factor to his collapse—an inflammation of the heart—was discovered only after his death.
Although such cases are rare, Myra Cocker believes that they justify a closer look at cardiac health among athletes. Sudden cardiac death may result from a genetic heart abnormality that has always been present, revealing itself only when the heart is pushed to its limit during intense exercise. But what if the training regimen of elite athletes actually causes underlying cardiac damage, which could itself pose a risk for sudden cardiac death? Together with her supervisor, Dr. Matthias Friedrich, Cocker is taking a close look at the hearts of athletes to investigate that very question. Magnetic resonance imaging gives her detailed images of the structure, tissue characteristics, and functioning of the heart. These scans show that a startling proportion of elite athletes—77%, compared to 17% of non-athletes—have some degree of scar tissue, called fibrosis, which can impair the functioning of the heart.
Fibrosis is the end result of sustained injury to the heart. It is often seen in patients with cardiac inflammation who turn up at emergency rooms complaining of symptoms such as chest pain, shortness of breath, and fatigue. Because of this link between fibrosis and cardiac inflammation, Cocker wants to know whether athletes also show signs of increased cardiac inflammation, and if so, why.
We already know that exposure to a cold or flu virus can lead to temporary inflammation of the heart. Yet elite athletes rarely interrupt their training for a minor virus such as a cold. Cocker has been investigating the consequences of such athletic devotion by imaging the hearts of athletes before, during, and four weeks after an acute cold. While the athletes were suffering cold symptoms, their hearts contracted less efficiently and were more likely to show signs of inflammation. Especially revealing, however, were the results four weeks after the cold. Inflammation normally resolves itself within four weeks, even among patients who show symptoms of cardiac inflammation. But almost half of Cocker's athletes still showed signs of cardiac inflammation four weeks after they experienced the cold symptoms.
Whether due to continued exertion during colds or simply performing at peak for sustained periods of time, fibrosis can have a significant impact on the functioning of an athlete's heart, reducing its ability to contract efficiently. Cocker suggests that fibrosis may lead to a plateau effect, in which athletes are no longer able to eke out additional performance from extra training. Cardiac imaging, which can identify athletes with fibrosis, may be able to predict which athletes will benefit from additional training, and which athletes have already reached their peak capabilities.
Although this line of research reveals some of the dangers involved in high-level athletic training, Cocker points out that much can be done to manage the risks. In some European countries, for instance, an athlete must pass a cardiac pre-screening exam before receiving the green light to participate in competitive sports. This simple measure can prevent many fatalities: in Italy, where rigorous pre-screening guidelines have been in place since 1982, the annual incidence of sudden cardiac deaths among athletes is now about one tenth of what it was before the program was established.
Canada currently has no pre-screening guidelines for its athletes, but Myra Cocker hopes to apply her research expertise to help develop some—so that Canadian athletes will be able to dream about owning the podium without compromising their health.