The Effect of Exercise on Serum and Salivary Cortisol in Male Children

Abstract

The purpose of this study is to examine serum and salivary cortisol responses to cycling exercise in male children, 10.6 ± 0.2 yr (mean ± SE). Each child performed a graded exercise test on a cycle ergometer to determine VO2
max. On a separate day a 30 minute bout of exercise at 70% of VO2
max was performed. Blood, obtained from a venous catheter, and saliva samples were collected at rest, at 15 and 30 minutes of exercise, and 15 minutes post exercise. The mean serum cortisol level at 15 minutes (7.94 ± 1.43ìg.dl-1) and 30 minutes (8.72 ± 1.77ìg.dl-1) of exercise and at 15 minutes post exercise (8.21 ± 1.59ìg.dl-1) were significantly greater than rest (5.54 ± 0.86ìg.dl-1). The increase in salivary cortisol levels over time approached (P = 0.08), but did not reach significance. However, effect size analysis indicates that increase in salivary cortisol at 30 minutes of exercise (0.64) and 15 minutes post exercise (0.62) was similar to the exchange in serum cortisol at these same two time points (0.72 and 0.66, respectively). Serum and
salivary cortisol were correlated (P < 0.05) at 15 minutes of exercise (r = 0.77)
30 minutes of exercise (r = 0.90) and 15 minutes post exercise (r = 0.84), but not at rest (r = 0.46). In conclusion, 30 minutes of sub-maximal exercise at 70% of VO2 max significantly increased serum cortisol level; and salivary and serum cortisol are correlated during and after exercise.