The effect of an intense period of fixtures on salivary cortisol and IgA concentrations in professional soccer players

Several studies have shown that various aspects of immune function and humoral responses are temporarily suppressed after high-intensity exercise (Pedersen, 1991; Shephard et al., 1994). The period post-exercise where aspects of the immune system are suppressed may increase susceptibility to upper respiratory tract infections (URTI) and has been referred to as the ‘open window’ (Nieman, 1994). Cortisol, which is described as an immunosuppressive and antiinflammatory agent (Weicker and Werle, 1991), has been shown to increase following intense exercise (Chicharro et al., 1998). In addition, a small progressive reduction in salivary IgA has been observed following repeated bouts of intermittent exercise (Sari-Sarraf et al., 2008). It has also been reported that salivary immunoglobulin A (sIgA) is decreased in ‘over-trained’ subjects (Pedersen et al., 2001).