Circadian effects on the acute responses of salivary cortisol and IgA in well trained swimmers

Abstract

Objective: To examine whether time of day significantly affects salivary cortisol and IgA levels before and after submaximal swimming. Methods: Fourteen male competitive swimmers (mean (SD) age 18 (3.2) years) volunteered to participate in the study. In a fully randomised, cross over design, each subject performed 5 × 400 m front crawl at 85 (1.2)% of their seasonal best time (277 (16) seconds), with one minute rest between each 400 m, at 0600 and 1800 hours on two separate days. Timed, unstimulated saliva samples were collected before and after exercise. Saliva samples were analysed for cortisol and IgA by radioimmunoassay and single radial immunodiffusion respectively. Results: Significant time of day effects (am and pm respectively) were observed in IgA concentration (0.396 (0.179) v 0.322 (0.105) mg/ml, p<0.05), IgA secretory rate (0.109 (0.081) v 0.144 (0.083) mg/min, p<0.01), and saliva flow rate (0.31 (0.23) v 0.46 (0.22) ml/min, p<0.001) before exercise (all values mean (SD)). Differences in cortisol levels before exercise (1.09 (0.56) v 0.67 (0.94) µg/dl) approached significance (p = 0.059). The exercise protocol did not significantly affect IgA concentration and secretory rate (p>0.05) but, in comparison with values before exercise, caused significant alterations in cortisol (p<0.01) and saliva flow rate (p<0.01). There was no significant interaction effect of time of day by exercise on any salivary variables measured (p>0.05). However, most of the values of the salivary variables before exercise were significantly inversely related to their exercise induced response (p<0.05). Conclusion: These results suggest a significant circadian variation in the variables measured before exercise, without showing a significant effect on their acute responses to exercise. V irtually all physiological and psychological variables show evidence of large rhythmic changes (24 hour rhythmicity), [1][2][3][4][5][6][7] and many physiological responses to exercise are influenced by the time of day effect.1 2 However, the time of day effects on the immunoendocrinological responses to exercise are not clear.8 Studies on salivary cortisol (an immunosupressive hormone) and IgA (the first line of defence against upper respiratory infections) in response to exercise appear equivocal, 9-20 yet these variables have been used extensively for monitoring athletes' health. A possible explanation for the variability found in the literature could be the difference in time of day at which the measurements were taken. The persistence of circadian rhythms during exercise conditions could result in erratic interpretation of the body's responses in sporting and clinical research and could invalidate experiments in which measurements were not taken at a consistent time of day.3 9 It could also have implications for exercise regimens that could lead to an overload of the immune system. Furthermore, the effects of circadian variation and exercise on potential triggers of immunosuppression may be synergistic. For example, exercising in the mornin...

Effect of sensory stimulation on salivary IgA secretion rate in karate players

“…The decline of salivary flow showed statistical significance on every session. That is in agreement with other studies [6,15,25]. In one study, the largest decline in flow rate occured after the most intense session [17].…”

“…The decrease in absolute concentration of IgA and secretion rate in response to exercise is in keeping with some prevous findings [9,14,15], but is not confirmed with others [6,15,31] [24]. The decrease in the saliva values observed after exercise is dependent on both the duration and intensity of the exercise [25].…”

Effects of training time on serum immunoglobulin alterations and cortisol testosterone responses in male athlete students

“…Also, the pre-test of the morning training group had a significantly different level comparing to the evening training group (p=0.0001). These results are similar to those reported by Bird [1], Dimitriou [6], investigations.…”

“…On the contrary, Bird [1] studied the effect of aerobic activity by weight training with 75% of one repetition maximum, in two different time (6 AM and 8 PM) and concluded that performing an aerobic activity in the evening in comparison with the morning cause significant decrease in cortisol concentration and increase of testosterone ratio to cortisol ratio. In another investigation, Dimitriou et al [6] …”

“…This endocrine adaptation causes the adjustment of muscular activity and glycogenolysis stimulation and facilitating of glyconeogenesis process [4,5]. Numerous studies have demonstrated the effect of various activities on hormones secretion and immunoglobulins [2,3,6,9]. Klentrou [7] showed that the intense aerobic activity decreases the amount of immunoglobulins and sets the body exposed to injury, especially in the upper respiratory tract infection while the physical activity with average intensity causes the increasing of IgA amount and diminishes…”