The human gastric intestinal tract(GIT) is inhibited by a vast number of microbiota that performs a number offunctions to keep the body healthy. These microorganisms in your gut create abarrier against infections or harmful substances from the outside world tryingto infiltrate your body. Microbiota also helps with metabolism, absorption ofnutrients, building and maintaining of the epithelium and supporting the immunesystem. GIT diseases such as Irritable Bowel Syndrome (IBS) and InflammatoryBowel Disease (IBD) are linked to an imbalance of gut micriobiota. Widersystemic metabolic conditions such as type 2 diabetes and obesity are alsoassociated with imbalanced gut microbe. The human gut is house to more than1 000 species of bacteria. Microbial settlement begins at birth and there are anumber of external and internal factors influencing the human gut micriobiota. External factors include the microbial loadof the immediate environment, what food is eaten, feeding habits, and thecomposition of the maternal microbiota you inherit form your mom.
Dietary andtemperature-related stresses can influence the sequence of microbes. Internalfactors include intestinal pH; microbial interactions; environmentaltemperature; physiological factors, such as peristalsis; bile acids; hostsecretions and immune responses; drug therapy; and bacterial mucosal receptors (Bull & Plummer, 2014) Interesting enough there is a gut–brain axis that is a communicationsystem allowing integrates neural, hormonal, and immunological signalingbetween the gut and the brain. This offers the intestinal microbiota a direct routeto access the brain. The brain will then command gastrointestinal functions inresponse. Gut microbiota is thus important to brain function. It was found thatgut microbe could even influence anxiety and depression.
A study showed that stress influences thecomposition of the gut microbiota and affects communication between the gutmicrobiota and the central nervous system. This way stress can influence theintegrity of the gut epithelium and altering the habitat of the intestinalmicrobiota promoting changes in microbial composition and metabolism leading topoor absorption of food, slow digestion and high risk of infections. It is well known that prebiotics, probioticsand a high-fiber diet rich in fruits, vegetables, legumes and whole grains havea positive effect on the gut microbes. Lately exercise was also added to this listas recent studies suggestedthat exercise could increase the amount of beneficial microbial species,improve the microflora diversity, and improve the development of non-harmfulbacteria. All of this improves human health.
Low intensity exercise can influence the GIT by decreasingthe transient stool time, thus reducing the contact time between harmfulbacteria and the gastrointestinal mucus layer. Exercise has protective effects,reducing the risk of colon cancer, diverticulosis, and inflammatory boweldisease. Exercise may reduce inflammatory infiltrate and protect the structureand integrity of the intestine (Monda et al.,2017). A study done on 40 elite, professional rugby players found exercisehas a beneficial impact on gut microbiota diversity and the rugby players hadlower inflammatory status than the two control groups (Clarke et al., 2014) Another study done on36 mice that were fed a normal or high-fat diet for 12- weeks and randomlyassigned to exercise or inactive groups also found better gut integrity andmore beneficial bacteria in theexercise group.
Specificmicrobiota were observed in the exercise group, including Faecalibacteriumprausnitzi, Clostridium spp., and Allobaculum spp. These microbes may provide protection to the gut throughoxygen detoxification of harmful bacteria. The good microbiota present in the exercising mice promotes ahealthy digestive tract by producing butyrate and lowering the oxygen tensionin the lumen. (Campbell et al.
, 2016) The microbiota has significant effects on metabolicfunctions. It produces short-chain fatty acids (SCFAs), such as n-butyrate,acetate, and propionate, which, can increase the nutrients availability andprovide more energy in the body. SCFAsare involved in the gut-brain axis, and it signals the brain to releaseappetite reducing hormones called peptide YY to help with satiety and neurotransmittersto convey the feeling of happiness.
It also acts as signaling molecules toregulate immune and inflammatory responses. N-butyrate reduces mucosalpermeability, allowing fewer harmful bacteria to enter the body (Monda et al.,2017) In a third study, 32 sedentary adults (18 lean, 14 obese) weresubjected to 6 weeks of training followed by a 6-week period of inactivity (Allen et al.,2017).
The participants trained for 30-60 minutes at moderate tohigh intensity for 3 days/week during the training period and continued withtheir habitual diet. The results of the study indicated a change in beneficialgut microbiota in the lean group during training. They found an increase inSCFA especially butyrate but the positive effect was reversed after theexercise was stopped. Diversity isimportant in all ecosystems to promote stability and performance. A variety ofmicrobiota also seems to be beneficial for the human body and may become a newindicator of health and disease. Exercise alone has shown to increase the amount ofbeneficial microbial species, improve the microflora diversity, and improve thedevelopment of commensal bacteria.