Effects of exercise in hot and humid conditions and bovine colostrum on salivary immune markers.

Abstract

The purpose of this study was to examine the effects of exercise in a hot and humid environment on salivary lactoferrin and lysozyme. A secondary aim was to quantify the effects of 14-day bovine colostrum (BC) supplementation on salivary lactoferrin and lysozyme at rest and following exercise in hot and humid conditions. Using a randomized, double-blind, and counterbalanced design, ten males (20±2 years, VO2max 55.8±3.7mLkg-1min-1, 11.8±2.7% body fat) ran for 46±7.7minat 95% of ventilatory threshold in a 40°C and 50% RH environment after 14-days of supplementation with either BC or placebo. Saliva was collected pre, post, 1-h, and 4-h post exercise, and was analyzed for lactoferrin and lysozyme using ELISA. There was an immediate increase in the concentration and secretion rate of lactoferrin and lysozyme (p<0.05) with exercise, but BC had no effect (p>0.05). Saliva flow rate was not different between conditions [(PLA: pre: 0.54±0.3, post: 0.44±0.3, 1-h: 0.67±0.3, 4-h: 1.0±0.4mLmin-1); (BC: pre: 0.58±0.2, post: 0.37±0.1, 1-h: 0.63±0.2, 4-h: 0.83±0.4mLmin-1)]. There were no differences in thermoregulatory markers (core temperature or physiological strain index) between BC and placebo trials. Interestingly, exercise-induced heat stress did not impair mucosal immune parameters, instead participants showed a transient increase in salivary lactoferrin and lysozyme. Further, 14-day BC supplementation had no effect on mucosal immunity at any time point.