Purpose: The aim of this cross-sectional study was to examine whether cardiorespiratory fitness and body composition have an effect on resting levels of salivary IgA (sIgA) and salivary alpha-amylase (sAA) in children. Methods: One hundred and thirty-two black South African children (age 10.05 ± 1.68y, 74 females, 58 males) participated in the study. Resting saliva samples were collected 90 minutes after waking. Body fat percentage was determined using a 4 site skinfold and cardio-respiratory fitness (predicted VO2max) was assessed using the 20 meter multi-stage shuttle run test. Results: The outcomes of one-way ANOVAs that examined the differences by BMI categories showed there were significant differences in weight (F = 83.64, df = 2, 129, P < 0.0001), BMI (F = 193.36, df = 2, 129, P < 0.0001), waist-to-hip ratio (F = 193.36, df = 2, 129, P < 0.0001), body fat percentage (F = 336.98, df = 2, 129, P = 0.0001), SBP (F = 5.72, df = 2, 129, P = 0.0042), DBP (F = 291.76, df = 2, 129, P < 0.0001), VO2max (F = 521.00, df = 2, 129, P < 0.0001), sAA concentration (F = 17.05, df = 2, 129, P < 0.0001), sAA secretion rate (F = 15.15, df = 2, 129, P < 0.0001), sIgA concentration (F = 11.30, df = 2, 129, P < 0.0001), and sIgA secretion rate (F = 8.08, df = 2, 129, P = 0.0005), between children of different BMI categories. Tukey’s post hoc analyses revealed that obese children had significantly (P < 0.01) higher weight, BMI, body fat percentage, DBP, SBP, sAA concentration and secretion rate, compared to overweight and normal weight children, as well as a significantly lower cardiorespiratory fitness than both normal (P < 0.001) weight and overweight (P < 0.05) children. In addition, sIgA concentration and secretion rate were significantly lower between normal weight and obese children (P < 0.01). Multiple linear regression revealed that BMI, DBP and VO2max predict sAA. BMI (P = 0.04) and DBP (P = 0.04) were found to be independent predictors of sAA concentration. Age and BMI category predicted sIgA secretion rate. BMI category (P = 0.0006) was found to be an independent predictor of sIgA secretion rate. Conclusion: This study suggests that obesity, based on BMI, has a major role to play in mucosal immunity and sympathetic activation and that obese children have elevated sympathetic activation, lowered mucosal immunity and poor cardio-respiratory fitness.
|Number of pages||1|
|Journal||Medicine and Science in Sports and Exercise|
|Publication status||Published - May 2014|