Can Noncardiac Syncope Occur during Exercise?

We describe the case of a 25-year-old athlete experiencing syncope during a 5-km running race. A thorough diagnostic workup reasonably excluded a cardiac disorder as the cause of syncope. The characterization of this episode of syncope as noncardiac appears to contradict the common belief that syncope during exercise has always a cardiac origin. Following a detailed history taking, it was revealed that the symptoms of the athlete started after a 180° turn of the route. This situation represents a setting relevant to a runner who stops suddenly after reaching the finish line and soon after experiences noncardiac syncope due to the abrupt cessation of muscle pump function of the lower limbs. Although the symptoms of the athlete in this report occurred during running, implying at a first glance the diagnosis of syncope occurring during exercise, a more detailed analysis of the circumstances indicated that these symptoms were in essence presenting after exercise from a pathophysiological view. The distinction between syncope occurring during and after exercise may be challenging enough for athletic activities involving a sudden stop of the running activity, such as for running races with sudden inversion of the route and sports characterized by rapid "starts and stops."