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Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes

View Article: PubMed Central - PubMed

ABSTRACT

Fatigue, mood disturbances, under performance and gastrointestinal distress are common among athletes during training and competition. The psychosocial and physical demands during intense exercise can initiate a stress response activating the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal (HPA) axes, resulting in the release of stress and catabolic hormones, inflammatory cytokines and microbial molecules. The gut is home to trillions of microorganisms that have fundamental roles in many aspects of human biology, including metabolism, endocrine, neuronal and immune function. The gut microbiome and its influence on host behavior, intestinal barrier and immune function are believed to be a critical aspect of the brain-gut axis. Recent evidence in murine models shows that there is a high correlation between physical and emotional stress during exercise and changes in gastrointestinal microbiota composition. For instance, induced exercise-stress decreased cecal levels of Turicibacter spp and increased Ruminococcus gnavus, which have well defined roles in intestinal mucus degradation and immune function.

Diet is known to dramatically modulate the composition of the gut microbiota. Due to the considerable complexity of stress responses in elite athletes (from leaky gut to increased catabolism and depression), defining standard diet regimes is difficult. However, some preliminary experimental data obtained from studies using probiotics and prebiotics studies show some interesting results, indicating that the microbiota acts like an endocrine organ (e.g. secreting serotonin, dopamine or other neurotransmitters) and may control the HPA axis in athletes. What is troubling is that dietary recommendations for elite athletes are primarily based on a low consumption of plant polysaccharides, which is associated with reduced microbiota diversity and functionality (e.g. less synthesis of byproducts such as short chain fatty acids and neurotransmitters). As more elite athletes suffer from psychological and gastrointestinal conditions that can be linked to the gut, targeting the microbiota therapeutically may need to be incorporated in athletes’ diets that take into consideration dietary fiber as well as microbial taxa not currently present in athlete’s gut.

No MeSH data available.


Related in: MedlinePlus

Gut microbiota effects on mood disturbance, fatigue, insomnia and risk of depression during exercise. The putative mechanisms by which bacteria connects with the brain and influence behavior during exercise include bacterial subproducts that gain access to the brain via the bloodstream and the area postrema, via cytokine release from mucosal immune cells, via the release of gut hormones such as 5-hydroxytryptamine (5-HT) from enteroendocrine cells, or via afferent neural pathways, including the vagus nerve. Stress during intense period of training and competitions can influence the microbial composition of the gut through the release of stress hormones or sympathetic neurotransmitters that influence gut physiology and alter the habitat of the microbiota (reviewed by Mach [23]). Alternatively, host stress hormones such as noradrenaline might influence bacterial gene expression or signaling between bacteria, and this might change the microbial composition and activity of the microbiota.
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Fig3: Gut microbiota effects on mood disturbance, fatigue, insomnia and risk of depression during exercise. The putative mechanisms by which bacteria connects with the brain and influence behavior during exercise include bacterial subproducts that gain access to the brain via the bloodstream and the area postrema, via cytokine release from mucosal immune cells, via the release of gut hormones such as 5-hydroxytryptamine (5-HT) from enteroendocrine cells, or via afferent neural pathways, including the vagus nerve. Stress during intense period of training and competitions can influence the microbial composition of the gut through the release of stress hormones or sympathetic neurotransmitters that influence gut physiology and alter the habitat of the microbiota (reviewed by Mach [23]). Alternatively, host stress hormones such as noradrenaline might influence bacterial gene expression or signaling between bacteria, and this might change the microbial composition and activity of the microbiota.

Mentions: The central fatigue hypothesis states that increased of the neurotransmitter serotonin (5-hydroxytryptamine; 5-HTP) release is associated with sleep, drowsiness and central fatigue, which contribute to suboptimal physical performance (reviewed by Best et al [82], Fig. 3). Furthermore, low serotonin in the brain also causes mood disorders and depression as well as changes in gut transit, blood pressure, cardiac function and platelet aggregation (reviewed by Evans et al [83], Fig. 3). Approximately 95% of the body's serotonin is produced in the enterochromaffin cells (EC) of the intestines [8, 83], which plays a role in enteric motor and sensory functions such as visceral pain perception, further illustrating the gut-brain connection [84]. According to a review conducted by Best et al [82], about 2% of ingested tryptophan is used for the synthesis of serotonin. However, during exercise, serotonin levels might also be increased through other known pathways: (i) kynurenine pathway [21], and (ii) gut microbiota synthesis [85, 86].Fig. 3


Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes
Gut microbiota effects on mood disturbance, fatigue, insomnia and risk of depression during exercise. The putative mechanisms by which bacteria connects with the brain and influence behavior during exercise include bacterial subproducts that gain access to the brain via the bloodstream and the area postrema, via cytokine release from mucosal immune cells, via the release of gut hormones such as 5-hydroxytryptamine (5-HT) from enteroendocrine cells, or via afferent neural pathways, including the vagus nerve. Stress during intense period of training and competitions can influence the microbial composition of the gut through the release of stress hormones or sympathetic neurotransmitters that influence gut physiology and alter the habitat of the microbiota (reviewed by Mach [23]). Alternatively, host stress hormones such as noradrenaline might influence bacterial gene expression or signaling between bacteria, and this might change the microbial composition and activity of the microbiota.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5121944&req=5

Fig3: Gut microbiota effects on mood disturbance, fatigue, insomnia and risk of depression during exercise. The putative mechanisms by which bacteria connects with the brain and influence behavior during exercise include bacterial subproducts that gain access to the brain via the bloodstream and the area postrema, via cytokine release from mucosal immune cells, via the release of gut hormones such as 5-hydroxytryptamine (5-HT) from enteroendocrine cells, or via afferent neural pathways, including the vagus nerve. Stress during intense period of training and competitions can influence the microbial composition of the gut through the release of stress hormones or sympathetic neurotransmitters that influence gut physiology and alter the habitat of the microbiota (reviewed by Mach [23]). Alternatively, host stress hormones such as noradrenaline might influence bacterial gene expression or signaling between bacteria, and this might change the microbial composition and activity of the microbiota.
Mentions: The central fatigue hypothesis states that increased of the neurotransmitter serotonin (5-hydroxytryptamine; 5-HTP) release is associated with sleep, drowsiness and central fatigue, which contribute to suboptimal physical performance (reviewed by Best et al [82], Fig. 3). Furthermore, low serotonin in the brain also causes mood disorders and depression as well as changes in gut transit, blood pressure, cardiac function and platelet aggregation (reviewed by Evans et al [83], Fig. 3). Approximately 95% of the body's serotonin is produced in the enterochromaffin cells (EC) of the intestines [8, 83], which plays a role in enteric motor and sensory functions such as visceral pain perception, further illustrating the gut-brain connection [84]. According to a review conducted by Best et al [82], about 2% of ingested tryptophan is used for the synthesis of serotonin. However, during exercise, serotonin levels might also be increased through other known pathways: (i) kynurenine pathway [21], and (ii) gut microbiota synthesis [85, 86].Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

Fatigue, mood disturbances, under performance and gastrointestinal distress are common among athletes during training and competition. The psychosocial and physical demands during intense exercise can initiate a stress response activating the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal (HPA) axes, resulting in the release of stress and catabolic hormones, inflammatory cytokines and microbial molecules. The gut is home to trillions of microorganisms that have fundamental roles in many aspects of human biology, including metabolism, endocrine, neuronal and immune function. The gut microbiome and its influence on host behavior, intestinal barrier and immune function are believed to be a critical aspect of the brain-gut axis. Recent evidence in murine models shows that there is a high correlation between physical and emotional stress during exercise and changes in gastrointestinal microbiota composition. For instance, induced exercise-stress decreased cecal levels of Turicibacter spp and increased Ruminococcus gnavus, which have well defined roles in intestinal mucus degradation and immune function.

Diet is known to dramatically modulate the composition of the gut microbiota. Due to the considerable complexity of stress responses in elite athletes (from leaky gut to increased catabolism and depression), defining standard diet regimes is difficult. However, some preliminary experimental data obtained from studies using probiotics and prebiotics studies show some interesting results, indicating that the microbiota acts like an endocrine organ (e.g. secreting serotonin, dopamine or other neurotransmitters) and may control the HPA axis in athletes. What is troubling is that dietary recommendations for elite athletes are primarily based on a low consumption of plant polysaccharides, which is associated with reduced microbiota diversity and functionality (e.g. less synthesis of byproducts such as short chain fatty acids and neurotransmitters). As more elite athletes suffer from psychological and gastrointestinal conditions that can be linked to the gut, targeting the microbiota therapeutically may need to be incorporated in athletes’ diets that take into consideration dietary fiber as well as microbial taxa not currently present in athlete’s gut.

No MeSH data available.


Related in: MedlinePlus