Relationship between physical activity and resting secretory immunity in children

This study examined relationships among physical activity, body fat and salivary immonoglobulin A (sIgA) levels in adolescent children of Southern Ontario. Gender differences on these factors were also assessed. Sixty-one grade-five students (10-1 lyrs), males (n=29) and females (n=31), who had not received a flu vaccination in the past 12 months, participated in the study. They were assessed for: aerobic power (20-m shuttle run), relative body fat (bioelectrical impedance analysis), sIgA, sIgA/albumin ratio, and salivary Cortisol. Each subject completed the Habitual Activity Estimation Scale and the Participation Questioimaire. Students wore a pedometer for 48h to estimate their average total distance traveled per day. The results show 40% of the children were over 25% body fat and 50% of them spend less than five hours per day in any physical activities. Salivary IgA was not related to salivary Cortisol, physical activity, fitness level or body fat in this age group. There were no gender differences in sIgA and Cortisol levels. Boys had a significantly higher aerobic power and daily distance traveled, but reported similar organized and fi-ee time activity participation levels as the girls. The test-retest reproducibility for salivary Cortisol was 0.663 (p<0.01), while long term sIgA and sIgA/albumin ratio reproducibility was non-significant for repeated measurements taken after six weeks. It was found that salivary IgA has not been shovm to be a stable measure in children, in contrast to the results found in the literatiu-e that tested adults and the relationship with physical activity, fitness level and body fat.