Research Article Markers of Biological Stress and Mucosal Immunity during a Week Leading to Competition in Adolescent Swimmers E. Papadopoulos, 1 C. Muir, 2 C. Russell, 1 B. W. Timmons, 3 B. Falk, 1 and P. Klentrou 1 1 Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada L2S 3A1 2 Department of Psychology, Centre for Neuroscience, Brock University, St Catharines, ON, Canada L2S 3A1 3 Department of Pediatrics, McMaster University, Hamilton, ON, Canada L8S 4L8 Correspondence should be addressed to P. Klentrou; nklentrou@brocku.ca Received 28 October 2013; Accepted 3 June 2014; Published 12 June 2014 Academic Editor: Dan Nemet Copyright © 2014 E. Papadopoulos et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this study we examined changes in the salivary concentrations of immunoglobulin A (sIgA), cortisol (sC), testosterone (sT), and testosterone-to-cortisol ratio (T/C) in 21 competitive swimmers, 11–15 years old, during a week leading to competition as compared to a control (noncompetition) week. No day-to-day changes or signifcant diferences between weeks were observed for sIgA (47.9 ± 4.4 versus 54.9 ± 5.2 g/mL for control versus competition week, resp.), sC (2.7 ± 0.2 versus 2.5 ± 0.2 ng/mL for control versus competition week, resp.), and T/C ratio (83.4 ± 7.0 versus 77.9 ± 7.7 for control versus competition week, resp.). In contrast, sT was signifcantly lower during the week of competition (154.5 ± 11.3 pg/mL) as compared to the control week (181.3 ± 11.5 pg/mL) suggesting that the swimmers were in a catabolic state, although this did not have a negative efect on their performance. In conclusion, salivary cortisol did not change between the two weeks, and thus competition stress was relatively low, and mucosal immunity was unafected in these young athletes prior to competition. 1. Introduction Young, competitive swimmers can be subject to intense train- ing. Tis may have a potential efect on their mucosal immu- nity since there is some evidence in the literature that long periods of training can lead to immunosuppression in adult swimmers [1–3]. In particular, salivary Immunoglobulin A (sIgA), the most abundant marker of mucosal immunity, has been shown to decrease in response to prolonged training in adult swimmers [4]. However, another study found no signifcant changes in sIgA afer 15 weeks of training in elite swimmers [5] while there are no such studies in adolescent swimmers. Competition events have been shown to increase stress, refected by higher cortisol levels [6, 7]. According to Filaire et al. [6], salivary cortisol increased during a major compe- tition in judo athletes, with a similar response reported for volleyball and basketball players prior to a signifcant match [7, 8]. All these studies measured the levels of salivary cortisol and other stress hormones without taking into account the variability of these hormones. On the other hand, people with high hormonal variability may be more adaptive and able to cope with situations such as stress; thus, the day-to-day variability of stress hormones (as measured by the % coef- fcient of variation) may be a better indication of adaptability than a single measurement [9, 10]. Te interaction between stress and immune markers due to competition is not clear, especially in child athletes. He et al. [8] reported an inverse relationship between sIgA and cortisol levels in adult basketball players during competition periods, but there are no relevant studies that examine the potential chronic efect of stress on immunity markers in the days leading to a competition in young athletes. As the number of children and adolescents that engage in high per- formance sports at a steadily younger age has increased, it is important to investigate any potential health implications of youth sport participation. Studies on the cumulative efect of training and competition on young athletes’ health and per- formance are, therefore, timely. Te purpose of this study was to determine whether the combination of training and Hindawi Publishing Corporation Journal of Immunology Research Volume 2014, Article ID 234565, 7 pages http://dx.doi.org/10.1155/2014/234565