Gut health has been a hot topic lately. Many research articles and studies have been stating that the gut is the second brain, that your gut health impacts all other bodily functions, or your seemingly unrelated symptoms could be because of poor gut health[*][*][*].
Are they correct? How is the gut so powerful?
You may be asking yourself what exactly is "the gut", or how your exercise routine is impacting your gut. Let's break down these broad statements so that you can feel powerful in your decisions around food and exercise.
What is the Gut?
The gut is also known as the gastrointestinal (GI) tract. The GI tract consists of the mouth, esophagus, stomach, small intestine, large intestine, and colon. When articles refer to "the gut", it is so much more than your stomach or what most people see as the fat hanging over their pants, including:
Houses the organs
The gut is all the digestive organs working together to breakdown the foods introduced to the body and to utilize the nutrients from that food to function properly.
Digestion is the mechanical (chewing and peristalsis) and chemical (enzymes and acid) breakdown of food. Once the food is broken down into absorbable molecules, these nutrients pass into the blood and lymph to be circulated and used in all cells.
Leads to nutrient absorption
Proper digestion leads to proper absorption of nutrients (vitamins and minerals) to keep the rest of our organs functioning as they should to keep our hormones in balance, our weight controlled, and our thinking clear.
All of this occurs under perfect conditions: enzymes being produced at the correct time, signals sent from the brain to the stomach to create a properly acidic environment to break down food into absorbable molecules, peristalsis to move nutrients through the GI tract and absorbed before our fan-favorite... a beautiful bowel movement.
Rest for successful digestion
So, what are the perfect conditions for successful digestion? You want your nervous system in a parasympathetic state or rather a "rest and digest" state.
The parasympathetic state lets the body know it is safe to slow down and focus on digestion which means the stomach can create an acidic environment, the proper enzymes, and mucous for proper breakdown and absorption of food particles.
When we introduce stress, these functions are impacted. Stress reduces stomach acid which then impacts intestinal integrity and creates a beautifully dark and moist environment for food to ferment, rancidify, or putrefy.
How does exercise change digestion?
What impact does exercise have on the nervous system and the digestive system? Broadly, exercise is a stress to the nervous system but not all stress is bad. Let’s dig into that a little more:
Stress, in the form of pathogens, irritants, damage, psychological stress, exercise, etc., produces an inflammatory response in the body. This inflammation is necessary and welcomed when combined with a healthy diet and lifestyle.
Inflammation creates pathways for immune products to get inside the affected tissue by dilating blood and lymphatic vessels and increasing tissue permeability[*].
Inflammation also produces reactive oxygen species (ROS) that fight off pathogens, also known as a bacterium, virus or another microorganism that may cause disease. When there are not enough antioxidants, the free radicals produced by the ROS run wild and can damage cells, DNA, proteins, and tissues.
This is why we see inflammation and stress as toxic to the body. If there is chronic stress, which we see in this modern daily life, then inflammation and free radicals damage more than what was intended.
But guess what? The digestive system is a sub-set of the immune system. Meaning it is a physical barrier to pathogens and it is also about to produce a powerful adaptive immune response. All that to say, a healthy digestive system and GI tract is beneficial for a healthy athlete.
Exercise is a stress to the body putting load on muscles and bones and tearing tissues. But exercise also increases lymphatic movement and insulin sensitivity, which is extremely beneficial for overall health.
Restorative exercises for digestion
There are many different kinds of exercises that range from restorative to intense.
More restorative exercises are very beneficial to incorporate daily such as:
- Daily chores
A 2019 study showed that just three consecutive days of walking for 60 minutes a day resulted in an insulin iAUC decrease of 34% meaning the body improved its response to insulin[*]. This is important to understand because when insulin receptors are impaired and stop responding well to insulin diabetes ensues.
According to the Centers for Disease Control and Prevention, about 45% of the American population is diabetic or pre-diabetic. And we know that Type 2 diabetes is a lifestyle disease, meaning that it is caused by our lifestyle choices and habits.
Other ways exercise influences digestion and health
Here are a few other ways exercise influences digestion and health:
Influences hunger hormones
Depending on the intensity of the exercise, it has been shown that ghrelin, the hormone that increases hunger, is decreased following the completion of exercise. This is because of the stress response induced by exercise. The body will down-regulate hunger to focus on getting blood to the heart and muscles during exercise.
Increases insulin sensitivity
Light movement such as walking helps the body become more sensitive to insulin. This is important so that the insulin receptors are more "accepting" towards the hormone and allow cells to absorb glucose instead of "resisting" glucose and causing inflammation, insulin resistance, and quite realistically type 2 diabetes[*].
Improves bowel movements
Exercise is helpful in improving bowel movement by increasing the circulation of blood and lymph, it also has been shown to increase intestinal transit time. Meaning exercise increase peristalsis (contractions of the intestinal lining) in the intestines and colon leading to a regular bowel movement in less time than usual.
Bowel movements (daily and twice daily) are important for detoxification, movement of gut bugs (good and bad), and to keep movement in the colon to ensure no fermentation, bacterial build-up, or intestinal permeability[*].
Increases gut flora diversity
Exercise has also been shown to help diversify the intestinal microbiome, meaning that movement helps bacterium move throughout the gastrointestinal tract and flourish when healthy.
It is important to have healthy bacteria within the GI tract to keep a balance of "good" and "bad" gut bugs. More diversity in intestinal bacteria is beneficial in reducing intestinal permeability. We want to have strong intestinal walls to make sure only tiny molecules of vitamins and minerals and getting into the blood and lymph system.
When our intestinal walls become damaged, it is easier for bigger food particles, unwanted bacteria, parasites, and items seem by the body as invaders to enter into the bloodstream and cause inflammation and dysbiosis leading to digestive upset. Keeping active with exercise provides a healthy balance of gut bugs to create a happy intestinal environment.
The best exercises for digestion
The following exercises are beneficial for digestion. Try incorporating them daily.
With a combination of deep breathing, stretches that target abdominal organs, and twists that massage and wring out stuck intestinal toxins, yoga is a great way to wake up and support organs for better digestion[*].
Aim to walk 3-5 miles a day or 10k steps at a leisurely-brisk pace. Humans are meant to move and the digestive and lymph system thrives off of daily movement. Having a step goal will get toxins moving out of your body while also increasing insulin sensitivity which will help your body function properly while eating.
You can literally improve your digestion through sleeping. Giving yourself a full 7-9 hours of sleep will also give your gastrointestinal tract 7-9 hours of no new food to work on breaking down. It is able to focus on moving nutrients through to the colon while also moving bacteria and toxins through and hopefully out the next morning through a bowel movement. Sleep is also extremely beneficial in helping clear toxins from the body and improve immune function which will aid digestion.
Exercise does influence digestion. We want to be mindful of how intensely we are moving and make sure to have periods of rest, restorative exercise, and flow to get the added benefits of insulin sensitivity, improved gut bug diversity, better bowel movements, and manageable cravings and hormones.