BACKGROUND: The increasingly deepened studies have proved that moderate exercise training can effectively cope with the psychological and physiological stress, and improve the immunological functions of the body.OBJECTIVE: To observe the effect of exercise on the patients in pschoneuroimmunology.DESIGN: A randomized controlled observation.SETTING: Huaiyin Teachers College and the School of Physical Education of Yangzhou University.MATERIALS: The experiment was carried out at the Laboratory of Exercise Biochemistry of the School of Physical Education of Yangzhou University between September and November 2002. Fifty-four male SD rats were randomly divided into quiet control group (n=8), psychological stress group (n=8), stress plus 30-minute exercise group (n=7), stress plus 60-minute exercise group (n=8), 30-minute exercise group (n=7), 60-minute exercise group (n=8), shock group (n=8).METHODS: Quiet control group: There was neither exercise nor stress.Shock group: No exercise was involved, and shock was used as the source of stimulation in the stress group. Psychological stress group: The rats under stress did not receive shock, but just watched the process of shock in the shock group as bystanders in order to produce psychological stress through visual sense and hearing sense. Each stress lasted for 30 minutes,once every other day for 2 continuous weeks. 30-minute exercise group: In the first week, the rats adapted to training for 10 minutes every day, and then they swam without load for 30 minutes once a day for 8 weeks. 60minute exercise group: In the first week, the rats adapted to training for 30minutes every day, and then they swam without load for 60 minutes once a day for 8 weeks. Stress plus 30-minute exercise group: The rats received the same exercise as that of the 30-minute exercise group and the same stress as that applied to the psychological stress group. Stress plus 60-minute exercise group: The rats received the same exercise as that of the 60-minute exercise group and the same stress as that of the psychological stress group. The contents of corticosterone and interleukin-2 in serum were detected with radioimmunoassay, and the number of T lymphocyte subgroups was determined with the method of enzyme labeling.MAIN OUTCOME MEASURES: ① Effects of exercise of moderate and small intensity on serum corticosterone and interleukin-2 of stress rats. ②Effects of exercise of moderate and small intensity on T lymphocyte subgroups of CD3+, CD4+ and CD8+ in stressed rats.RESULTS: ①Effects of exercise of moderate and small intensity on serum corticosterone and interleukin-2 of stress rats: The serum levels of interleukin2 in stress rats were significantly lower than that of the rats in the control group, and the serum contents of corticosterone were significantly higher than that in the control group. The serum levels of interleukin-2 in the exercise group were significantly higher than that in the control group, and the serum contents of corticosterone were significantly higher than that in the control group. Compared with stress group, the level of interleukin-2 was significantly higher and the contents of corticosterone were markedly lower in the stress plus 30-minute exercise group and stress+60-minute exercise group. ② Effects of exercise of moderate and small intensity on T lymphocyte subgroups of CD3+, CD4+ and CD8+ in stress rats: Compared with the control group, the numbers of T lymphocyte subgroups were all significantly in the 30 and 60minute exercise groups. Compared with the stress group, the levels of CD3+and CD4+ in the stress plus 60-minute exercise group were significantly higher than thosein the stress group. The CD4+/CD8+ level had no significant difference between the stress plus 30-minute exercise group and stress group, but not lower than those in the stress group.CONCLUSION: Repeated psychological stress caused greater psychological response from rats, and inhibited the immnological function, and exercise of moderate and small intensity had better protective effect on the immunological function of rats under psychological stress, and the exercise of moderate intensity much more greatly improved the anti-stress ability of rats. The possible mechanism lies in the fact that exercise of moderate and small intensity produced better adaptability for hypothalamic-pitutiary-adrenal axia, changed the in vivo excretion of stress hormone, and then maintained the stability of immunological function.