Salivary immunoglobulin A in healthy adolescent females: Effects of maximal exercise, physical activity, body composition and diet

BACKGROUND: The primary purpose of this study was to examine the effect of acute maximal exercise (VO₂ max test) on salivary immunoglobulin A (SIgA) responses in adolescent females. A secondary aim was to examine the relationship between resting SIgA levels and VO2max physical activity, body composition, and diet. METHODS: Fifty healthy female adolescents completed a laboratory-based VO₂ max test, assessment of body composition via hydrodensitom-etry, a validated physical activity questionnaire (PAQ-A), and a three-day food diary. Unstimulated saliva was collected before, and 5 and 120 minutes after VO₂ max testing. Absolute SIgA (ng/mL) concentration was determined using an enzyme-linked immunosorbent assay. Secretion rate of SIgA (ng/min) was calculated by multiplying absolute SIgA concentration by saliva flow rate (SFR, nL/min). RESULTS: A significant increase in absolute SIgA concentration (146.8±59.2 ng/mL) was noted immediately after VO₂ max testing (P<0.05) and returned to pre-exercise levels (120.1±54.1 ng/mL) by 120-min post-exercise (P>0.05). No significant VO2max test effects were observed for SIgA secretion rate and SFR (P>0.05). VO₂ max values (41.92±6.36 mL/kg/min) were correlated with body fat percentage (r=-0.59; P<0.01), PAQ-A total score (r=0.48; P<0.01), and acute changes in absolute SIgA levels (r=0.28; P<0.05). No significant associations were observed between dietary measures and resting SIgA levels or SFR (P>0.05) except for dietary fiber which correlated with resting absolute SIgA concentration (r=0.29; P<0.05). CONCLUSIONS: Findings indicate that acute graded maximal exercise results in a transient increase in absolute SIgA concentration and that these changes are associated with individual VO₂ max values.