Aim: To analyze changes in the gut microbiota of qualified female boxers at different stages of the training cycle, influenced by physical activity of differen intensity. Materials and Methods: The study involved nine qualified female boxers, who performed high-intensity training sessions. The study of changes in the state of the microbiota, namely its diversity, was carried out in two phases of the training cycle. A microbiological quantitative method was used, in-depth with species identification and detection of anaerobes, the unit of measurement of which was colony-forming units per gram (CFU/g). The quantitative assessment of microorganisms was performed using arithmetic mean values expressed and log-transformed values (log10 CFU/g). Results: High-intensity training loads were associated with microbiota changes indicative of dysbiosis. It is noticeable that the concentration of typical patho genic genera (Candida albicans, Klebsiella pneumoniae, Streptococcus) significantly increased during the post-competition period. At the same time, classic “beneficial” bacteria (Lactobacillus and Bifidobacterium) remained within normal limits, although Bifidobacterium showed some growth. Notably, Escherichia coli (a normal representative of the microbiome) exceeded the norm during the post-competition period. Conclusions: Increased training intensity in qualified female boxers resulted in alterations in gut microbiota composition, most notably a significant rise in Escherichia coli and other opportunistic microbes, while the levels of beneficial Lactobacillus and Bifidobacteria species remained relatively stable. These changes suggest early signs of dysbiosis, consistent with current evidence on the impact of extreme physical exertion on microbial health.