Salivary IgA responses to prolonged intensive exercise following caffeine ingestion.
OBJECTIVE
Prolonged, intensive exercise is associated with a reduction in concentration and secretion of salivary IgA (s-IgA). Saliva composition and secretion are under autonomic nervous system control, and caffeine ingestion, a widespread practice among athletes for its ergogenic properties, is associated with increased sympathetic nervous system activation. Therefore, this study investigated the influence of caffeine ingestion on s-IgA responses to prolonged, intensive exercise.


METHODS
In a randomized crossover design, 11 endurance-trained males cycled for 90 min at 70% VO2peak on two occasions, having ingested 6 mg x kg(-1) body mass of caffeine (CAF) or placebo (PLA) 1 h before exercise. Whole, unstimulated saliva samples were collected before treatment (baseline), preexercise, after 45 min of exercise (midexercise), immediately postexercise, and 1 h postexercise. Venous blood samples were collected from a subset of six of these subjects at baseline, preexercise, postexercise, and 1 h postexercise.


RESULTS
An initial pilot study found that caffeine ingestion had no effect on s-IgA concentration, secretion rate, or saliva flow rate at rest. Serum caffeine concentration was higher on CAF than PLA at preexercise, postexercise, and 1 h postexercise (P < 0.001). Plasma epinephrine concentration was higher on CAF than PLA at pre- and postexercise (P < 0.05). s-IgA concentration was higher on CAF than PLA at mid- and postexercise (P < 0.01), and s-IgA secretion rate was higher on CAF than PLA at midexercise only (P < 0.02). Caffeine ingestion did not affect saliva flow rate. Saliva alpha-amylase activity and secretion rate were higher on CAF than PLA (main effect for trial, P < 0.05).


CONCLUSIONS
These findings suggest that caffeine ingestion before intensive exercise is associated with elevated s-IgA responses during exercise, which may be related to increases in sympathetic activation.
School of Sport and Exercise Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom. N.C.Bishop@lboro.ac.uk
Nicolette C
NC
Bishop
Gary J
GJ
Walker
Gabriella A
GA
Scanlon
Stephen
S
Richards
Eleanor
E
Rogers
D000328:Adult; D001642:Bicycling; D002110:Caffeine / Q000008:administration & dosage*; D018592:Cross-Over Studies; D015444:Exercise; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis*; D008297:Male; D010919:Placebos; D012463:Saliva
D007070:Immunoglobulin A; D010919:Placebos; D002110:Caffeine