THE EFFECT OF EXERCISE ON SERUM AND SALIVARY CORTISOL IN MALE-CHILDREN

The purpose of this study was to examine serum and salivary cortisol r esponses to cycling exercise in male children, 10.6 +/- 0.2 yr (mean /- SE). Each child performed a graded exercise test on a cycle ergomet er to determine VO2max. On a separate day, a 30-min bout of exercise a t 70% of VO2max was performed. Blood, obtained from a venous catheter, and saliva samples were collected at rest, at 15 and 30 min of exerci se, and 15 min post-exercise. The mean serum cortisol level at 15 min (7.94 +/- 1.43 mu g.dl(-1)) and 30 min (8.72 +/- 1.77 mu g.dl(-1)) of exercise and at 15 min post-exercise (8.21 +/- 1.59 mu g.dl(-1)) were significantly greater than rest (5.54 +/- 0.86 mu g.dl(-1)). The incre ase in salivary cortisol levels over time approached (P = 0.08), but d id not reach significance. However, effect size analyses indicated tha t the increase in salivary cortisol at 30 min of exercise (0.64) and 1 5 min post-exercise (0.62) was similar to the change in serum cortisol al these same two time points (0.72 and 0.66, respectively). Serum an d salivary cortisol were correlated (P < 0.05) at 15 min of exercise ( r = 0.77), 30 min of exercise (r = 0.90), and 15 min post-exercise (r = 0.84), but not at rest (r = 0.46). In conclusion, 30 min of submaxim al exercise at 70% of VO2max significantly increased serum cortisol le vel; and salivary and serum cortisol are correlated during and after e xercise.