The quality and quantity of saliva may be important in defending against pathogens
transmitted via the buccal cavity. The aim of the present study was to examine the
effect of cycling to exhaustion at moderate and high intensity on various salivary
parameters and the time course of recovery. Eighteen male subjects of mixed physical
fitness took part in the study. Subjects performed two bouts of exercise on separate
occasions at least one week apart. Following an overnight fast, subjects cycled on
an electrically braked cycle ergometer at a work rate equivalent to 80 % VO2max until exhaustion. On another occasion they cycled on the same ergometer at 55
% VO2max for 3 h or to fatigue (whichever was sooner). The order of the rides was randomised.
Timed, unstimulated saliva samples were collected pre-exercise, during exercise, at
cessation of exercise and at 1, 2.5, 5 and 24 h post-exercise. Saliva samples were
analysed for lgA, total protein and osmolality. Saliva flow rate was significantly
reduced by exercise (P < 0.01). Saliva IgA concentration, secretion rate and ratio
to osmolality increased during exercise (P < 0.01). IgA to protein ratio did not change
significantly during exercise. Since saliva protein secretion rate increased during
exercise (P < 0.01) it appears that correcting for loss of saliva water by expressing
lgA relative to protein is misleading. lgA secretion rate and lgA to osmolality ratio
are more appropriate measures and neither parameter was lowered by exercise. The results
of this study indicate that exercise may detrimentally affect the quantity of saliva
produced, but not the quality of saliva. Furthermore, when exercise is to exhaustion,
the intensity of the bout does not appear to influence the saliva response. Neither
exercise protocol had any long term effect on saliva as all variables recovered within
1 h post-exercise.
Key words
Saliva - exercise - immunoglobulin A - immune function
