Abstract

Problem statement: An increase in exercise intensity enhances the immune system. However, concentrations of cortisol and cytokine responses as acute effects of different exercise intensities need to be comprehensively elucidated. The purpose of this study was to examine the effects of different exercise intensities on concentrations of salivary cortisol and interleukin-6, a proinflammatory cytokine, at four distinct time points. Research Methods: Forty-five participants were classified into three groups (15 participants/group): one control group and two groups undergoing aerobic exercise at 65-80% maximum heart rate and >80% maximum heart rate, respectively. Saliva samples were collected from each participant at 0, 45, 60, and 90 min to measure cortisol and interleukin-6 levels using enzyme-linked immunosorbent assay kits. Results: Salivary cortisol levels at 60 min after exercise significantly differed between the aerobic exercise at 65-80% maximum heart rate and control groups (P = 0.024). Compared with the control group, aerobic exercise in the 65-80% and >80% maximum heart rate showed significantly different effects on altered salivary interleukin-6 levels at 45 and 60 min after exercise (P = 0.004 and P = 0.016, respectively). At 60 min, the concentration of salivary interleukin-6 was significantly higher in the aerobic exercise at 65-80% maximum heart rate than in the ˃80% maximum heart rate group (P = 0.049). Conclusion: Our findings revealed that different intensities of acute aerobic exercise might induce high levels of salivary cortisol and interleukin 6. It would be a beneficial tool for healthy individuals as they strive to rate the work intensity of aerobic exercise.