Stress hormones released during high-intensity exercise:
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- Catecholamines (norepinephrine and epinephrine)
- Corticotrophin-releasing hormone (CRH)
- Arginine vasopressin (AVP)
- Adrenocorticotropic hormone (ACTH)
- Glucocorticoid hormones (e.g., cortisol)
- Gamma-aminobutyric acid (GABA)
- Neuropeptide Y
- Dopamine
- Short-chain fatty acids
- Serotonin
- Cytokines
- Activation pathways:
- Preganglionic sympathetic neurons in the intermediolateral cell column of the thoracolumbar spinal cord
- Hypophysiotropic neurons in the paraventricular nucleus of the hypothalamus (PVN)
- Anterior pituitary gland
- Adrenal cortex
- Modulation of autonomic nervous system:
- Sympathetic activation (fight or flight response)
- Parasympathetic modulation
- Factors influencing the stress response to exercise:
- Emotional stress
- Volume of physical exposure (intensity and/or duration of exercise session)
- Critical threshold of exercise intensity (~50–60% of maximal oxygen uptake [VO2max])
- Additional contributors to stress response:
- Gastrointestinal tract hormones (GABA, neuropeptide Y, dopamine)
- Microorganisms in the digestive tract (production of short-chain fatty acids, neurotransmitters, cytokines)
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5121944/
- The human gut houses over 100 trillion microorganisms, totaling around 9 million genes.
- Gut microbiota comprises five phyla and roughly 160 species in the large intestine.
- Functions of gut microbiota:
- Promotion of digestion and food absorption.
- Provision of folate, vitamin K2, and short-chain fatty acids (SCFAs).
- Neutralization of drugs and carcinogens.
- Modulation of intestinal motility.
- Protection against pathogens.
- Stimulation and maturation of the immune system and epithelial cells.
- Modulation of neurotransmitters (serotonin, GABA, dopamine) in response to stress.
Influence of gut microbiota on oxidative stress, inflammatory responses, metabolism, and energy expenditure during intense exercise.- Diet’s impact on gut microbiota:
- Dietary changes account for up to 57% of gut microbiota changes.
- Short-term consumption of animal- or plant-based diets can rapidly alter microbiota composition.
- ADA guidelines recommend specific macronutrient intake for athletes.
- Insufficient fiber and resistant starch intake may decrease microbiota diversity and function.
- Aim of systematic review:
- To summarize evidence on interactions between exercise-induced stress responses and gut microbiota.
- To explore effects on the health and performance of elite athletes.
- Secondary aim:
- To define dietary strategies for modifying microbiota composition.
- To improve overall health and performance by enhancing intestinal epithelium conditions, immune system response, stress response, energy availability, and inflammation levels in athletes.
