The risk of viral infections is known to be affected by physical activity, but little information is available regarding the more serious infections caused by bacteria. In this study, the investigators examined the relationship between leisure-time physical activity and suspected bacterial infections during a one-year follow up. Suspected bacterial infections were determined based on prescriptions for antibiotics. Via the use of Denmark's unique civil registration number (an identification number assigned to all citizens at birth), it was possible to link health survey information with information from nationwide registries.
Results showed that compared with sedentary behavior, low leisure-time physical activity was associated with a 10 percent lower risk of any suspected bacterial infection. Further, low and moderate levels of leisure-time physical activity were associated with a 21 percent and 32 percent reduction of suspected cystitis (urinary tract bacterial infections), respectively - compared with individuals classified as sedentary. Suspected respiratory tract bacterial infections, however, were not associated with physical activity level.