Development of the discipline of exercise immunology.

Interest in the influence of exercise upon the human white cell population dates back more than a 100 years. Thus, when introducing the third meeting of the International Society of Exercise Immunology in Brussels, Dr. Bente Klarlund-Pedersen noted that Schulte had already described an exercise-induced leukocytosis as early as 1893. However, for much of the following century interest remained strictly clinical, with physicians assessing the possible changes in vulnerability to bacterial and viral diseases that were induced by various forms of physical activity. In the absence of specific remedies, bed rest was a common medical recommendation for infectious disease, and if the patient recovered from the immediate infection there was often a substantial residual loss of physical condition. Army hospitals in particular were thus anxious to know whether recovery would be compromised if physical activity were to be encouraged during convalescence. Prominent concerns of this era were the influence of exercise upon anterior poliomyelitis and viral hepatitis. The paralysis resulting from the anterior poliomyelitis virus was generally localized to body parts that had been active, and it seemed most likely to develop in those who continued to engage in vigorous exercise in the face of early symptoms (46, 57, 119, 120). Data on viral hepatitis also suggested a need for rest in the acute phase of the disease (1, 65, 115, 128), although most authors concluded that in this condition exercise could be resumed during convalescence, provided that the patient was no longer severely jaundiced (5, 32, 136).