Evidence-based Sports Medicine

Evidence-based Sports Medicine• acute phase response• viral myocarditis• infectious mononucleosis• hepatitis• gastroenteritis• respiratory infections• sudden death.Fever and/or acute infectious disease – generalconsiderationsFever is defined as 38° Celsius or higher oral or rectal temperature.It is associated with acute and chronic infections, muscle trauma,neoplasms, heat related illness, prolonged exercise and somemedications. It is difficult to different some of the effects of fever fromthe effects of the condition causing it; however, in general, it isrecognised that fever impairs muscle strength, 1 mental cognition andpulmonary perfusion. Additionally fever increases insensible fluid lossand increases overall systemic metabolism. 2 These factors alone or incombination are potentially detrimental to athletic performance.Additionally, decreased muscle strength could be seen as a potentialfactor for increased risk of injury although there are no studies tosupport this theory.The aerobic exercise capacity, as determined from submaximalexercise studies, is decreased during fever. On the other hand, theobserved maximal oxygen uptake has been shown to be unaffectedduring short lasting, experimental pyrogen induced fever as well as inconditions of thermal dehydration. There do not appear to be anystudies where maximal oxygen uptake has been measured duringongoing infection and fever (most likely for ethical reasons).Therefore, the rate and magnitude of decrease of the maximal aerobicpower during ongoing febrile infections in humans is unknown. 3Acute infections are associated with a variety of immune systemresponses that are triggered by cytokines and are correlated to fever,malaise and anorexia along with other signs and symptoms. Acuteviral illness can potentially hinder exercise capabilities by affectingmultiple body systems, including cardiac, pulmonary, muscular, fluidstatus, and temperature regulation. 4–7 Heir et al examined theinfluence of respiratory tract infection and bronchial responsivenessin elite cross country skiers compared with inactive controls. Thestudy found that on a methacholine challenge test, there was atransient increase in bronchial responsiveness in athletes whoundertook physical exercise during the symptomatic period of theirrespiratory tract infections, but not in the inactive controls. The84