Figure 3. Changes of SIgA secretion rate before appearance of URTI symptoms. 1–3 day: 1–3 days before appearance of URTI symptoms. Appearance of URTI symptoms: the day when URTI symptoms were exhibited.
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Previous studies (Mackinnon et al., 1993; Gleeson et al., 1999) that focused on the relationship between appearance of URTI symptoms and SIgA level assessed the data by absolute value or percent changes from pre-training. In the present study, we assessed the data by the percent changes from baseline. The data of baseline were calculated from the SIgA secretion rate of each subject without any symptoms of URTI. Our present study suggested that daily mucosal immunity particularly SIgA levels changed widely day by day during a training period and this change differed among subjects, if they performed the same protocol Thus it was necessary to consider the characteristic of individuals when we assessed SIgA level.