Introduction ! The innate and adaptive immune system compo- nents may be temporarily suppressed by either a single session [34] or repeated sessions of exer- cise [26]. There are epidemiological and experi- mental reports that strenuous exercise increases the susceptibility to upper respiratory tract infec- tions (URTI) [33]. Lowered salivary immunoglob- ulin A (s-IgA), as the predominant component in the secretions lining the mucosal surface, or chronic s-IgA deficiency has been associated with an increased incidence of URTI [19]. The increased frequency of URTI attributable to decreased s-IgA in elite athletes may be due, at least in part, to the repetitive intensive-exercise sessions undertaken without sufficient recovery between them. It has been suggested that an imbalance between train- ing/competition stress and recovery can lead to chronic fatigue, under-performance and more immunodepression [21]. Competing and/or train- ing on successive days may therefore compound the effects of a single session of exercise. Various authors have examined the response of cellular indices of immune function in soccer players. Rebelo et al. [36] suggested that players who were exposed to long-term training could exhibit variations in circulating leukocyte and lymphocyte subpopulations. Malm et al. [30] showed that after a period of intensified training, soccer players experienced decreased T and B cell numbers in the circulation, affecting their capa- bility to activate the immune system and poten- tially resist infections. These changes may be re- flected in components of saliva which would con- stitute a readily accessible marker of mucosal im- munity. Changes in s-IgA have been coincident with or preceded the appearance of URTI in colle- giate soccer players [31]. Concentrations of s-IgA are reported to be sup- pressed in response to a single bout of high-in- tensity exercise [20], remain either unaltered [42] or are increased in response to moderate- low-intensity exercise [4,25]. Daily intense exer- cise may have a cumulative suppressant effect on s-IgA output. Mackinnon and Hooper [28] re- Abstract ! Failure to recover fully between sessions has been suggested to cause immunodepression. There- fore, the cumulative effects of soccer-specific in- termittent exercise undertaken on different days 48 h apart on salivary IgA, cortisol and total pro- tein concentration were investigated. Nine male subjects completed two trials of soccer-specific intermittent exercise 48 h apart on a motorised treadmill. Timed unstimulated saliva samples were collected immediately before and after exer- cise, and 24 and 48 h post-exercise. Salivary IgA concentration (EX 1 : 215 ± 160 to 335 ± 246 and EX 2 : 144 ± 93 to 271 ± 185 mg • l –1 , p = 0.007), os- molality (p = 0.001) and total protein (p = 0.001) increased immediately following exercise in both trials and decreased 24 h afterwards, whereas sa- liva flow rate decreased significantly (p = 0.015) before returning to pre-exercise values 24 h post- exercise. The IgA secretion rate, IgA to osmolality ratio, IgA to total protein, solute secretion rate, total protein secretion rate, and cortisol did not differ between the time-points. The results sug- gest that performing two bouts of moderate in- tensity soccer-specific intermittent exercise 48 h apart does not suppress resting salivary IgA con- centration significantly although a small progres- sive reduction in salivary IgA was observed. These findings may not extend to successive competitive soccer games when vulnerable play- ers might experience clinically relevant reduc- tions in s-IgA. Effects of Repeated Bouts of Soccer-Specific Intermittent Exercise on Salivary IgA Authors V. Sari-Sarraf 1, 2 , T. Reilly 2 , D. Doran 2 , G. Atkinson 2 Affiliations 1 Faculty of Physical Education and Sport Sciences, University of Tabriz, Tabriz, Iran 2 Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom Key words l " repeated exercise l " immunoglobulin A l " cortisol accepted after revision October 16, 2006 Bibliography DOI 10.1055/s-2007-965427 Published online July 5, 2007 Int J Sports Med 2008; 29: 366 – 371 © Georg Thieme Verlag KG Stuttgart • New York • ISSN 0172-4622 Correspondence Dr. Vahid Sari-Sarraf Faculty of Physical Education and Sport Sciences University of Tabriz 29 Bahman BLVD 51666 14774 Tabriz Iran Phone: + 98 41 13 39 32 54 Fax: + 98 41 13 35 60 08 vsarisarraf@yahoo.com 366 Sari-Sarraf V et al. Soccer-Specific and Repeated Exercise and s-IgA… Int J Sports Med 2008; 29: 366 – 371 Physiology & Biochemistry