The Effects of Prolonged Strenuous Exercise on Salivary Secretion of IgA Subclasses in Men

Low levels of secretary IgA (sIgA) have been associated with recurrent upper respiratory tract infection (URTI). Saliva contains approximately 60% sIgA1 and 40% sIgA2 in normal adults. Because sIgA1 is more susceptible to proteases degradation produced by mucosal pathogens, the higher the proportion of sIgA1, may increase the risk of bacterial mucosal infection. The aim of the present study is to investigate the effects of acute prolonged intensive exercise on saliva output rate and salivary concentrations of sIgA1 and sIgA2. Following approval by the local Ethics Committee, eight male volunteers (age 21.3 ± 1.0 years, body mass 66.8 ± 2.0 kg, max 2 O V& 52.5 ± 2.1 mL·kg-1·min-1, peak power 259 ± 6 watt; means ± SEM) performed either a single bout of cycling at 55% peak power for 2 h (started at 9:00) or a separate resting trial separated by at least a week in a counterbalanced design. Timed, unstimulated saliva samples and venous blood samples were obtained at 10 min before exercise (PreEX), after 58-60 min (Mid-EX, saliva only) and during the last 2 min of exercise (Post-EX), and at 1 h (P-EX-1h), and 2 h (P-EX-2h, saliva only) after exercise. The concentrations of sIgA and sIgA1 were determined by ELISA. The results showed that a 2-h cycling at 55% peak power significantly decreased blood glucose concentration (P<0.01) and increased plasma concentrations of cortisol and adrenaline (both P<0.01). However, there were no significant effects on saliva flow rate, sIgA level, and sIgA1/sIgA ratio. These findings suggested that a single bout of cycling at 55% peak power for 2 h does not appear to acutely affect oral immunity.