Response of salivary peroxidase to exercise intensity

Oral peroxidase, one of the most important salivary antioxidant enzymes, is subjected to alternation due to various body conditions. The aim of this study was to assess the effect of exercise intensity on salivary peroxidase activity. Using a randomized design, ten healthy male university students (mean age, 23.22; s _x = 2.34 years) completed treadmill runs with initial velocity 6.73 km/h at the rate of 1.58 km/h increase every 3 min until exhaustion. Unstimulated whole saliva collected over a 5-min period in pre-weighed tubes before, immediately after exercise, and 1 h after exercise was analyzed for total protein and saliva peroxidase activity. The saliva flow rate ranged from 0.08 to 1.40 ml min⁻¹ at rest and was not significantly affected by the exercise. Peroxidase activity in each sample was measured using 4-amino antipyrine as substrate. In the incremental exhaustion run and also at 75% VO_2max, the secretion rates of peroxidase increased. No significant changes in saliva flow rate were observed in any treadmill run. Treadmill runs at 75% VO_2max and to exhaustion increased the activity of peroxidase immediately after exercise which decreased after 1 h. It was concluded that short-duration, high-intensity exercise increases the activity rate of peroxidase despite no change in the saliva flow rate. These effects appear to be associated with changes in sympathetic activity and not the hypothalamic pituitary adrenal axis.