Time-of-Day Effects on Markers of Mucosal Immunity Response to a Bout of Swimming Intermittent Exercise in Elite male Swimmers

High-level athletes necessarily do exercise training at different times-of-day (rather morning & afternoon). The main purpose of this study was to determine the diurnal variation effect on responses of mucosal immune indices inclusive saliva flow rate (SFR)، alpha-amylase (sAA)، salivary immunoglobulin A concentration (sIgA) and sIgA secretion rate (sIgASR) to a training set of intermittent swimming (including: 12×100m front crawl at mean 92% maximum heart rate) in the elite male swimmers. For this reason، in a counterbalanced design، 9 male swimmers of swim national team (age: 17. 9±3. 1 years) participated in two exercise trails (7:30h: AMEX and 17:00h: PMEX) separated by at last 5 days. Unstimulated whole saliva samples were obtained before and after exercise، and again 1، 3 and 24h later. Mean heart rate، weight lose and mood state was the same at the both trials (p>0. 05)، but temperature was higher in PMEX (p<0. 05). Basis levels of SFR، sIgASR and sAA activity unlike with sIgA were higher in PMEX than AMEX (p<0. 05). sIgA was increased immediately after exercise (p<0. 001) despite of no change in SFR by drinking water adlibitum، that was caused by increased sIgASR (p<0. 005); These changes are associated with increase in sAA activity. Also، the responses of sIgASR and sAA unlike with SFR and sIgA concentration were affected by diurnal variation (p<0. 001). It appears that these changes properly are due to diurnal variation in adrenergic function. Nevertheless، a 1h to 3h rest was enough to return the changes to basis status.