BackgroundAthletes will increase their state anxiety under stress situations, which will lead to the decline of sports performance. The improvement of anxiety by probiotics has been reported, but there is a lack of research in the athlete population. The purpose of the current study is to explore the effectiveness of probiotics in improving athletes’ state anxiety and sports performance under stress situations.MethodsWe conducted this single-arm study in Chongqing Institute of Sports Technology. In the 8-week study, 21 Chongqing young divers were (...) given probiotic Bifidobacterium animalis subsp. lactis BB-12 daily. The state anxiety and sports performance of athletes were measured before, during, and after the intervention, and the gut microbiota of athletes was measured before and after the intervention.ResultsThe intervention results showed that cognitive state anxiety, somatic state anxiety, and anxiety emotion were improved. In terms of gut microbiota, the intervention did not change the gut microbial composition but increased the abundance of Bifidobacteriaceae. At the 8th week, the performance of athletes under stress was significantly improved.LimitationsFirst of all, due to the restriction of the number of subjects in this study, there was no control group. Secondly, although the athletes’ diet was recorded in this study, the influence of this factor on gut microbiota was not eliminated. Finally, the anxiety level of the athletes in this study was obtained through a self-report, lacking physiological data in state anxiety.ConclusionThe results show that probiotics intervention can improve the state anxiety of athletes under stress situation and improve the performance of athletes under stress situation. (shrink)