Microbial Bowel Infections-Induced Biochemical and Biological Abnormalities among Young Egyptian Swimmers: Associated Risk Factors Affecting Swimming Performance Running title: Swimmers’ Microbial Bowel Infections and Swimming Performance

Abstract Swimmers’ personal hygiene affects the spread of microbes in swimming pools. The present study aimed to determine the incidence of microbial infections among young Egyptian swimmers and its impact on biochemical parameters, and swimming performance. From January 2020 to June 2021, 528 public club swimmers were examined cross-sectionally. Swimmers were divided into two groups according their scores in the competition (group1 with high score and group 2 with low score). Stool samples, biochemical parameters and complete blood picture were assessed. Biological measures were evaluated directly after swimming. Microbial infections were 54% for intestinal parasitosis, 2.8% for H. pylori. Blastocystis spp. and Cryptosporidium spp. infected 24.1% and 23.3% of swimmers, respectively. Infection rates among swimmers’ groups varied according to gender, age, swimming duration and frequency. Infected swimmers with cryptosporidiosis had higher ALT, WBCs, and differential cells but lower AST levels. The results revealed high prevalence of Blastocystis spp., Cryptosporidium spp., and microsporidia. Swimming habits, frequency, and duration influenced the infectious status that induced anemia, abnormal blood pressure and heart rate. Giardiasis, showed reduction in the biochemical markers including ferritin, lactoferrin, iron and transferrin among group2 as compared to group1. Thus, raising swimmers’ hygiene awareness and targeting health education is obliged.