Influence of excessive exercise on immunity, metabolism, and gut microbial diversity in an overtraining mice model

The purpose of this study was to evaluate the negative influence of excessive exercise on immunity, substance and energy metabolism as well as gut microbiota in mice. Firstly, an overtraining model of Male Kunming mice was established by high-intensity swimming exercise for 4 weeks. Then, a series of evaluation indicators, including the routine blood analysis, immune organ coefficient, digestive enzymes, and aquaporins expression levels of small intestine and colon tissue, histological examinations of liver, spleen, small intestine, and colon, were determined based on this model. Furthermore, 16S rRNA gene sequencing was also employed to measure the microbial composition in gut. The results found that immune parameters, substance and energy metabolism of all mice was altered and disturbed after high-intensity swimming for 4 weeks, led to an atrophy of thymus and spleen as well as abnormal structural changes in liver when compared to non-swimming mice. Besides, excessive swimming mice had lower microbial diversity compared to non-swimming mice. However, there was no significant difference in gut microbial taxa between the two groups. The data indicated that excessive exercise exhibits negative impacts on immunity, substance and energy metabolism as well as gut microbial diversity.