Effect of time of day exercise on acute responses of salivary IgA, cortisol,α-amylase and total protein in female swimmers

To examine whether time of day significantly affects salivary IgA, cortisol, α-amylase and total protein levels before and after sub-maximal swimming. Fourteen female swimmers (age 13±1.33 years, weight 48±4.75 kg, Vo2max 45.92±3.96 ml/kg/min) volunteered to participate in the study. In a fully randomized, cross over design, each subject performed 10×200 m front crawl at 80% of their seasonal best time, with one minute rest between each 200 m, at 08:00 and 18:00 hours on two days aware. Timed, unstimulated saliva samples were collected before and after exercise. Saliva samples were analyzed by two-factor analysis of variance (ANOVA) with repeated measures. Statistical significance was accepted at p<0.05. Significant time of day effects (am and pm respectively) were observed in s-IgA, S-IgA, cortisol, and saliva flow rate, αamylase and total protein before exercise (P<0.05). The exercise protocol did not significantly affect s-IgA but, in comparison with values before exercise, caused significant alterations in cortisol, S-IgA, saliva flow rate, αamylase and total protein (P<0.05). There was no significant interaction effect of time of day by exercise on any salivary variables measured except αamylase. These results suggest a significant circadian variation in the variables measured before exercise, with showing a significant effect on their acute responses to exercise except s-IgA and a significant interaction effect of time of day by exercise on salivary αamylase.