It has frequently been reported that attacks of polio have occurred after moderate to severe exertion. Football players, marathon runners, and other athletes have contracted polio so soon after drills, contests, and the like, as to suggest a causal relationship between the exertion and the onset of the disease.
Medical journals contain such reports.
Voss, Bremer, de Rudder, Petersen, Nase have made such reports. Bremer's case was that of a student who contracted polio after a difficult mountain climb. Petersen and de Rudder observed two small epidemics following athletic contests. The athletes, who were between 13 and 19 years of age, were reported as being in good health and trained in athletics at the time of the contests. Eleven boys became ill with polio within a week after the contest.