The Effects of Postexercise Feeding on Saliva Antimicrobial Proteins

The purpose of this study was to determine the effects of a carbohydrate (CHO) and protein (PRO) drink consumed immediately after endurance exercise on saliva antimicrobial proteins known to be important for host defense. Eleven male runners ran for 2 hr at 75% VO2max on 2 occasions and immediately postexercise were provided, in randomized order, either a placebo solution (CON) or a CHO-PRO solution containing 1.2 g CHO/kg body mass (BM) and 0.4 g PRO/kg BM (CHO-PRO). The solutions were flavor and volume equivalent (12 ml/kg BM). Saliva flow rate, lysozyme, alpha-amylase, and secretory (S) IgA concentrations were determined from unstimulated saliva samples collected preexercise, immediately postexercise, and every 30 min until 180 min postexercise. CHO-PRO ingestion immediately postexercise resulted in a lower saliva flow rate than with CON at 30 and 60 min postexercise. Saliva lysozyme concentration increased immediately postexercise in both trials compared with preexercise (p< .05), and CHO-PRO ingestion immediately postexercise resulted in a higher saliva lysozyme concentration in the first hour of recovery than with CON (125% greater at 30 min, 94% greater at 60 min; p< .01). Saliva SIgA concentration decreased below preexercise concentrations 90-150 min postexercise (p< .001), with no effect of CHO-PRO. Saliva alpha-amylase activity was unaffected by exercise or CHO-PRO refeeding. CHO-PRO refeeding did not alter the secretion rates of any saliva variables during recovery. In conclusion, immediate refeeding with CHO-PRO evoked a greater saliva lysozyme concentration during the first hour of recovery after prolonged exercise than ingestion of placebo but had minimal impact on saliva alpha-amylase and SIgA responses.