The effect of three types of water-based training protocols on thymus atrophy and specific indicators of cellular immune senescence in aged male rats.

The collective detrimental impact of aged naive lymphocytes and thymus atrophy on the aging of the immune system can be mitigated by exercise. Hence, this research aims to explore the effects of three methods of water-based exercises on immune system aging and thymus atrophy in elderly rats. Thirty-two 24-month-old rats, with an average weight of 320 ± 5 g, were randomly allocated into four groups of endurance training (n = 8), resistance training (n = 8), combined training (n = 8), and control (n = 8).The training protocols (10 weeks) were conducted four times a week in a container measuring 50 × 50x100 cm filled with water at 30 ± 1 °C. The evaluation of naïve and memory T lymphocytes was conducted for the intervention groups based on the expression or lack of expression of the CD28 and CD57 markers in the subsets of CD4 + and CD8 + T cells. Naïve T cells were represented by CD28 + CD57- T lymphocytes, memory T cells were represented by CD28- CD57- T lymphocytes, aged naïve T cells were indicated by CD28 + CD57 + lymphocytes, and aged memory T cells were represented by CD28- CD57 + lymphocytes. The findings of the study showed that all three exercise protocols resulted in a significant decrease in levels of memory CD8, aged CD8, naive and naive CD4 and CD8, and aged memory, as well as an increase in levels of CD4, CD8, CD4 + , and naive CD8 when compared to the control group. It was observed that thymus atrophy, memory CD4, and aged CD4 had a significant decrease only in the combined exercise group compared to the control group, with no significant differences observed in these indicators for the resistance and endurance groups. Furthermore, the ratio of CD4 to CD8 remained unchanged across all groups. The findings of this study suggest greater efficacy of combined training in enhancing specific health indicators of cell immunity among elderly populations. Moreover, engaging in water exercises of all three types of combined, resistance, and endurance training are deemed safe activities for older individuals to bolster their immune system and mitigate the aging process of T cells.