Effects of different exercise intensities or durations on salivary IgA secretion

Abstract

Purpose: This study aimed to examine changes in salivary immunoglobulin A (s-IgA) secretion at different intensities or durations of acute exercise.

Methods: Twelve healthy untrained young males were included in randomized crossover trials in Experiment 1 (cycling exercise for 30 min at a work rate equivalent to 35%, 55%, and 75% maximal oxygen uptake [ $\dot{\text{V}}$ O_2max]) and Experiment 2 (cycling exercise at 55% $\dot{\text{V}}$ O_2max intensity for 30, 60, and 90 min). Saliva samples were collected at baseline, immediately after, and 60 min after each exercise.

Results: Experiment 1: The percentage change in the s-IgA secretion rate in the 75% $\dot{\text{V}}$ O_2max trial was significantly lower than that in the 55% $\dot{\text{V}}$ O_2max trial immediately after exercise (- 45.7%). The percentage change in the salivary concentration of cortisol, an s-IgA regulating factor, immediately after exercise significantly increased compared to that at baseline in the 75% $\dot{\text{V}}$ O_2max trial (+ 107.6%). A significant negative correlation was observed between the percentage changes in saliva flow rate and salivary cortisol concentration (r = - 0.52, P < 0.01). Experiment 2: The percentage change in the s-IgA secretion rate in the 90-min trial was significantly lower than that in the 30-min trial immediately after exercise (-37.0%). However, the percentage change in salivary cortisol concentration remained the same.

Conclusion: Our findings suggest that a reduction in s-IgA secretion is induced by exercise intensity of greater than or equal to 75% $\dot{\text{V}}$ O_2max for 30 min or exercise duration of greater than or equal to 90 min at 55% $\dot{\text{V}}$ O_2max in healthy untrained young men.

Keywords: Exercise duration; Exercise intensity; Open window; Oral immune function; Salivary IgA.

Fig. 1

Experimental protocol in this study. Experiment 1: Trial 1 (cycling exercise for 30 min at 35% $\dot{\text{V}}$O_2max), Trial 2 (cycling exercise for 30 min at 55% $\dot{\text{V}}$O_2max), Trial 3 (cycling exercise for 30 min at 75% $\dot{\text{V}}$O_2max). Experiment 2: Trial 2 (cycling exercise for 30 min at 55% $\dot{\text{V}}$O_2max), Trial 4 (cycling exercise for 60 min at 55% $\dot{\text{V}}$O_2max), Trial 5 (cycling exercise for 90 min at 55% $\dot{\text{V}}$O_2max). $\dot{\text{V}}$O_2max: maximal oxygen uptake

Fig. 2

Effects of different exercise intensities on the percentage change in saliva flow rate (A), salivary IgA concentration (B), and salivary IgA secretion rate (C) from baseline in healthy untrained young males (n = 12). Data are expressed as mean ± SD. IgA: Immunoglobulin A; $\dot{\text{V}}$O_2max: maximal oxygen uptake. *P < 0.01 vs post at 35% $\dot{\text{V}}$O_2max. †P < 0.01 vs post at 55% $\dot{\text{V}}$O_2max. ‡P < 0.05 vs baseline at 35% $\dot{\text{V}}$O_2max. §P < 0.01 vs baseline at 75% $\dot{\text{V}}$O_2max. ¶P < 0.01 vs post in each trial. #P < 0.05 vs post in each trial

Fig. 3

Effects of different exercise intensities on the percentage change in salivary cortisol concentration from baseline in healthy untrained young males (n = 12). Data are expressed as mean ± SD. $\dot{\text{V}}$O_2max: maximal oxygen uptake. *P < 0.01 vs post at 35% $\dot{\text{V}}$O_2max. **P < 0.01 vs post-60 at 35% $\dot{\text{V}}$O_2max. †P < 0.01 vs post at 55% $\dot{\text{V}}$O_2max. ††P < 0.01 vs post-60 at 55% $\dot{\text{V}}$O_2max. ‡P < 0.05 vs baseline at 75% $\dot{\text{V}}$O_2max. §P < 0.01 vs baseline at 35% $\dot{\text{V}}$O_2max. ¶P < 0.01 vs post at 35% $\dot{\text{V}}$O_2max

Fig. 4

Correlation between percentage changes in salivary cortisol concentration and percentage changes in saliva flow rate among different exercise intensities in healthy untrained young males (n = 12)

Fig. 5

Effects of different exercise durations on the percentage change in saliva flow rate (A), salivary IgA concentration (B), and salivary IgA secretion rate (C) from baseline in healthy untrained young males (n = 12). Data are expressed as mean ± SD. IgA: Immunoglobulin A. *P < 0.05 vs post at 30 min. †P < 0.05 vs post in each trial

Fig. 6

Effects of different exercise durations on the percentage change in salivary cortisol concentration from baseline in healthy untrained young males (n = 12). Data are expressed as mean ± SD