Objectives: Old age is associated with irregularities in many aspects of body immune system function. During this period, the immune responses decline with increasing age. In other words, with decreasing number of immune cells, which are responsible for detecting and direct attack to contaminated cells, the immune response decreases and results in failure of the immune system. As sports activities could affect the immune system and old age is associated with progressive immune failure, the study of the effects of exercise on the immune system function in old age becomes important. Therefore, this study aimed to investigate the effects of selected combined exercises (aerobic and resistance training) on the serum level of cortisol and immunoglobulins in inactive elderly men.

Methods & Materials: In this quasi-experimental study, 24 subjects were selected by convenience sampling method. Their age and body mass index ranged 60–70 years and 22–25 kg/m2, respectively. Then, they were randomly assigned into 2 groups (experimental [n=12] and control [n=12]). The experimental group started the combined training exercise, and the control group continued their inactive usual routines. The combined training exercise (aerobic-resistance) included running on a treadmill for 20 minutes per session, 3 sessions per week, for 8 weeks, with an intensity of 60% to 70% HRR. Furthermore, the resistance training comprised 10 circling stationary movements of leg flexion, leg extension, leg press, scott, underarm stretch, chest press, iron cross with dumbbells, biceps flexion, triceps extension, and rowing motion with rope. This training included an intensity of 60% to 70% of one maximum repetition with extra load and 10 repetitions in 2 successive times with 30 seconds rest between each repetition and 2 minutes’ rest between each movement. In this study, the blood samples were taken 24 hours before the exercise and 24 hours after the last session of the exercise. We used nephelometer instrument and binding kit site to measure the IgG, IgM, and IgA levels. The cortisol level was measured by Gamacounter and RIA kit by the immunoradiometric method. To evaluate the consumed oxygen, we used the protocol on treadmill instrument. In order to compare intra- and inter-group mean variables, we used analyses of variance for repeated measures. The significant level was set at P<0.05.

Results: The results indicated that the combined exercises reduced IgG level (12.75%) in the elderly people (P=0.04). Although the level of serum IgM was also reduced (15.93%), this decrease was insignificant (P=0.31). Furthermore, no significant change was seen in the IgA level (P=0.90). The cortisol level was significantly increased (8.33%) in the experimental group P=0.001). Based on the results, the mean intergroup changes in the levels of IgA, IgA, and IgM were not significant (P>0.05). However, a significant difference was seen between 2 groups with regard to serum cortisol level (P<0.05).

Conclusion: Doing physical activities is one of the key factors in changing the function of the immune system. This issue is associated with the intensity, duration, kind of exercise, body readiness, nutrition, mental status, and hormonal factors. Based on the results, long and intensive exercises with an increase in the catabolic process may weaken the immune system of the older people.