ACUTE INFECTION - METABOLIC RESPONSES, EFFECTS ON PERFORMANCE, INTERACTION WITH EXERCISE, AND MYOCARDITIS

Acute infections are associated with multiple host responses that are triggered by cytokines and correlated to fever, malaise and anorexia, The purpose of this systemic acute phase host reaction (''the acute ph ase response'') is to mobilize nutrients for the increased needs of th e activated immune system, as well as for energy production and tissue repair, Important effects include wasting of striated muscle, degrada tion of performance-related metabolic enzymes and, concomitantly, dete riorated central circulatory function. These effects result in decreas ed muscle and aerobic performance, the full recovery of which may requ ire several weeks to months following week-long febrile infections. Al so during early infection and fever, prior to the development of muscl e wasting, performance is compromised by other mechanisms. Strenuous e xercise may be hazardous during ongoing infection and fever and should always be avoided. In infection, muscle wasting seems to be less pron ounced in the conditioned (trained) host than in the unconditioned hos t. Acute myocarditis most often has a viral etiology but bacteria and their toxins may also be the cause. Furthermore, slow-growing bacteria , previously difficult to diagnose, have emerged as potential ''new'' causes of subacute to chronic myocarditis. Since myocarditis may or ma y not be associated with fever, malaise, or catarrhal symptoms, athlet es should be taught the symptoms suggestive of myocarditis. Whenever m yocarditis is suspected exercise should be avoided.