KEYSTONE, COLO. — The rules are simple and straightforward about when a physician should allow an athlete with an upper respiratory tract infection to return to play.
It is the clinical evaluation that is not always so easy, said Lisa R. Callahan, M.D., at the annual meeting of the American Orthopedic Society for Sports Medicine.
The general rule is that when athletes have symptoms only above the neck, such as nasal congestion or a sore throat, they can participate, but only at 50% normal intensity, said Dr. Callahan, the medical director of the Women's Sports Medicine Center at the Hospital for Special Surgery, New York.
If symptoms are below the neck, such as myalgias, shortness of breath, or vomiting, the athlete should not participate.
But the real concern is myocarditis, which can arise with a number of viral, bacterial, and fungal infections. And, much of the time, this kind of myocarditis is going to have very vague clinical signs and symptoms, Dr. Callahan said.
Most individuals with myocarditis associated with an infection will make a complete recovery. But it is estimated that infection-related myocarditis may be the cause of 20% of fatal arrhythmias in athletes.
The most important sign to evaluate when looking for myocarditis in an athlete is tachycardia, remembering that many athletes will normally have a low resting heart rate, and possibly also tachypnea, Dr. Callahan said.
Other general symptoms of myocarditis include fatigue, fluid retention, palpitations, and fever. Patients may have normal laboratory values or may have an elevated white blood cell count or erythrocyte sedimentation rate. Chest x-ray and ECG may be normal in some cases.
The list of infectious agents known to be associated with myocarditis is long, but examples include cytomegalovirus; Coxsackie, influenza, and Epstein-Barr viruses; salmonella, staphylococcus, streptococcus, and clostridia; and Candida and histoplasmosis.
Myocarditis can have two stages: the infectious stage, lasting 7–14 days, when the virus directly kills myocytes; and, sometimes, an immune response stage, which occurs later and can have a variable duration.
Physicians concerned about myocarditis should be alert for its other specific signs, such as chest pain, new onset of exertion-associated dyspnea, or changes in heart rate or blood pressure. Prolonged fatigue and low-grade fever are also signs of myocarditis.
According to guidelines from the American College of Cardiology, an athlete who has had myocarditis should have two echocardiograms, one at 3 months and one at 6 months, before returning to sports participation.
The American Academy of Pediatrics suggests that an athlete with a fever should be disqualified from exercise, as fever increases cardiac demand in a number of ways, Dr. Callahan noted.
In general, exercise has been shown definitively to improve immune function. However, very strenuous activity, such as that engaged in by marathoners, can suppress neutrophil function and curb natural killer cells.
Athletes tend to have a high caloric demand, due to a high metabolism, and fever also increases caloric demand, so athletes with a fever should be encouraged to eat, she said.