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 (mean age: 9.10 ± 1.80) were given probiotic Bifidobacterium animalis subsp. lactis BB-12 (1 × 109 colony-forming units/100 g) 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 (cognitive: Z = −3.964, P < 0.001; somatic: Z = −3.079, P = 0.003; anxiety: Z = −2.973, P < 0.001). In terms of gut microbiota, the intervention did not change the gut microbial composition (such as α diversity and β diversity) but increased the abundance of Bifidobacteriaceae. At the 8th week, the performance of athletes under stress was significantly improved (χ2 = 7.88, P = 0.019).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.
Objective: The aims of this study are as follows: (1) to understand the relationship between gut microbiota and the choking phenomenon in diving athletes, and (2) to regulate the gut microbiota in diving athletes by drinking yogurt containing Bifidobacterium animalis subsp. lactis BB-12 and observe changes in the choking phenomenon in diving athletes. Methods: Experiment 1: A total of 20 diving athletes were tested in low- and high-pressure situations. Gut microbiota (n = 18) composition was then determined and differences in the gut microbiota composition among diving athletes who presented choking vs. no choking were identified. Experiment 2: A total of 16 divers who presented choking were divided into a high yogurt group (n = 6) and a low yogurt group (n = 10) for 15 days. Results: (1) The content of Veillonellaceae in divers who presented choking was significantly higher when compared to divers who did not present choking (p < 0.05). Bifidobacteriaceae (r = −0.52, p < 0.05) and Lactobacillaceae (r = −0.66, p < 0.05) were negatively correlated with the choking index. (2) During experiment 2, the average daily intake of the high yogurt group was 611.78 ± 94.94 mL and the average daily intake of the low yogurt group was 338 ± 71.45 mL and the abundance of Bifidobacteriaceae was significantly higher in the high yogurt group than in the low yogurt group. After the experiment, the choking index in the high yogurt group became significantly lower than that of the low yogurt group (z = −3.26, p < 0.001). Conclusion: The intake of yogurt containing B. animalis subsp. lactis can increase the abundance of Bifidobacteriaceae in elite diving athletes and their performance under high pressure. Hence, gut microbiota may affect the choking phenomenon in elite diving athletes.
In order to study the effect of MHD control on the separation flow of turbulent boundary layer in the scramjet inlet based on the assumption of low magnetic Reynolds number, considering the source term of turbulent electromagnetic dissipation, the numerical simulation method is developed for electromagnetic field coupled with flow field. A Mach 4 plate is adopted as the basic configuration to assess the accuracy of the solver’s source term of turbulent electromagnetic dissipation. On this basis, numerical simulation of MHD control on the separation flow of boundary layer in scramjet inlet is carried out to study the influence of different electric field strengths and magnetic induction intensity on it. The results show that applying MHD local control alleviates the boundary layer separation in the scramjet inlet. Under different electric field strengths and magnetic induction intensity, the separation vortex’s scale significantly changes. The scale of the separation zone continues to decrease when the electric field strength or magnetic induction intensity increases, and the effect of MHD control is more significant.
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