The effects of post-exercise feeding on saliva anti-microbial proteins

The purpose was to determine the effects of a carbohydrate (CHO)-protein (PRO) drink, consumed immediately after endurance exercise on saliva anti-microbial proteins known to be important for host defence. Eleven male runners ran for 2 h at 75% VO2max on two occasions, and immediately post-exercise were provided, in randomised order, either a placebo solution (CON), or a CHO-PRO solution containing 1.2 gCHO·kg-1BM and 0.4 gPRO·kg-1BM (CHO-PRO). Both solutions were flavour and volume equivalent (12 ml·kg- 1BM). Saliva flow rate, lysozyme, α-amylase, and secretory (S) IgA concentrations were determined from unstimulated saliva samples collected pre-exercise, immediately post-exercise and every 30 min until 180 min post-exercise. CHO-PRO ingestion immediately post-exercise resulted in a lower saliva flow rate compared with CON at 30 and 60 min post exercise. Saliva lysozyme concentration increased immediately post-exercise in both trials compared with pre-exercise (P< 0.05), and CHO-PRO ingestion immediately post-exercise resulted in a higher saliva lysozyme concentration in the first hour of recovery compared with CON (125% greater at 30 min; 94% greater at 60 min, P< 0.01). Saliva SIgA concentration decreased below pre-exercise concentrations 90-150 min post-exercise (P< 0.01) with no effect of CHO-PRO. Saliva α-amylase activity was unaffected by exercise or CHO-PRO re-feeding. CHO-PRO re-feeding did not alter the secretion rates of any saliva variables during recovery. In conclusion, immediate re-feeding with CHO-PRO evoked a greater saliva lysozyme concentration during the first hour of recovery after prolonged exercise compared with ingestion of placebo, but had minimal impact upon saliva α-amylase and SIgA responses.