SALIVA COMPOSITION AND EXERCISE

Little attention has been directed toward identifying the changes whic h occur in salivary composition in response to exercise. To address th is, our article first refers to the main aspects of salivary gland phy siology, A knowledge of the neural control of salivary secretion is es pecially important for the understanding of the effects of exertion on salivary secretion. Both salivary output and composition depend on th e activity of the autonomic nervous system and any modification of thi s activity can be observed indirectly by alterations in the salivary e xcretion. The effects of physical activity (with reference to factors such as exercise intensity and duration, or type of exercise protocol) on salivary composition are then considered. Exercise might indeed in duce changes in several salivary components such as immunoglobulins, h ormones, lactate, proteins and electrolytes. Saliva composition might therefore be used as an alternative noninvasive indicator of the respo nse of the different body tissues and systems to physical exertion. In this respect, the response of salivary amylase and salivary electroly tes to incremental levels of exercise is of particular interest. Beyon d a certain intensity of exercise, and coinciding with the accumulatio n of blood lactate (anaerobic threshold or AT), a 'saliva threshold' ( Tsa) does indeed exist. Tsa is the point during exercise at which the levels of salivary cx-amylase and electrolytes (especially Naf) also b egin to rise above baseline levels. The occurrence of the 2 thresholds (AT and Tsa) might, in turn, be attributable to the same underlying m echanism, that of increased adrenal sympathetic activity at high exerc ise intensities.