Acute Effects Of Different Exercise Modes On Salivary Iga And Plasma Cortisol Secretory Responses

Salivary Immunoglobulin A (IgA) prevent bacterial attachment to the mucosal surfaces. High-intensity or long-term exercise causes a transient decrease in oral immune function through decreased salivary IgA secretion, and this response is associated with exercise-induced stress, such as cortisol. However, it is unclear whether differences in exercise modes affect salivary IgA and plasma cortisol secretory responses. PURPOSE:The purpose of this study was to examine whether differences in exercise modes affect salivary IgA and plasma cortisol secretory responses to a single bout of exercise. METHODS:Seven healthy young males with no exercise habits participated in the study. Subjects randomly performed two conditions: moderate-intensity continuous exercise (MICE) for 20 min cycle exercise at a work rate equivalent to 70% VO2max, and high-intensity interval exercise (HIIE, same total exercising volume to MICE) for 20 min cycle exercise, consisting of five 2 min bouts at 90% VO2max with 2 min active recovery at 50% VO2max. Saliva and blood samples were collected before, immediately after, 30 min after each exercise condition. The salivary IgA secretion rate was calculated from salivary IgA concentration and saliva volume per minute. RESULTS:In MICE, change in salivary IgA secretion rate at immediately after and 30 min after exercise was significantly lower than that before exercise (P < 0.05), but did not change in HIIE. In addition, the amount of change (area under the curve) in salivary IgA secretion rate in MICE was lower than that in HIIE (P < 0.05). Plasma cortisol concentration did not change in both MICE and HIIE. However, there was a significant negative correlation between salivary IgA secretion rate and plasma cortisol concentration in MICE (r = -0.544, P < 0.05). CONCLUSIONS:These results suggest that the salivary IgA secretory response may differ with different exercise modes. In MICE, the reduced salivary IgA secretory response may be associated with the increase in systemic cortisol concentration. Supported by Grants-in-Aid for Scientific Research (#19 K22828, M. Iemitsu)