For starters, bowel problems are one of the most common causes of withdrawal from a competition. Approximately 30 to 65% of endurance athletes experience discomfort, ranging from simple bloating to much more disabling ailments. It is not only endurance athletes who are affected, but also team athletes and even strength athletes who suffer from intestinal disorders. Women are in the majority, partly because they are more prone to intestinal disorders such as Irritable Bowel Syndrome (IBS).
What can you do to avoid these discomforts and how can you remedy them? Holyfat takes a look at your digestive tract and reveals some of its secrets.
What is the digestive system?
Far from being a long pipe only good for crushing and transforming our food into nutrients (the very definition of digestion), the digestive tract is a complex organ, the seat of thousands of actions/reactions.
We can break it down into 3 parts:
- The upper aerodigestive tract: the mouth and the pharynx
- The digestive tract: esophagus, stomach, small intestine, large intestine, rectum
- Adjacent glands: salivary glands, liver, pancreas
The mouth and pharynx: Visualize the pharynx as the crossroads between the airways (located between the nasal cavity and the larynx) and the digestive tract (from the oral cavity to the esophagus). When the food bolus passes through the epiglottis, the larynx closes to prevent the food from passing into the airway (the pie hole, for those who know it). It is in the oral cavity (or the inside of your mouth) that digestion starts: thanks to a mechanical role (grinding food, chewing, moistening) and a chemical role (thanks to the enzymes contained in saliva, which break down starch, short and medium chain triglycerides - our famous MCTs). This leads to the formation of the food bolus, which will go to the esophagus during swallowing.
The digestive tract and the annexed glands: The digestive tract is responsible for transporting food, digesting it, absorbing nutrients and removing food residues. As you can imagine, all this takes time, energy and involves a lot of steps, physiological actions and chemical reactions.
To begin with, you should know that the digestive tract is far from being just a tube, as we have mentioned. It has several types of movement:
- Segmentation (contraction/relaxation of longitudinal smooth muscle) which mixes intestinal contents and secretions to facilitate digestion and absorption
- Peristalsis (contraction/relaxation of longitudinal smooth muscles) which allows the progression of the food bolus. It is a reflex movement.
- Stirring: this occurs in the stomach and allows the mixing of the food bolus with gastric secretions to facilitate the digestion of food and the crushing of food particles
- Mass movements: at the level of the colon this time, these are powerful contractions that allow the digestive residues to be propelled in order to eliminate them
It is therefore far from being a long quiet river for our food. The whole system is highly vascularized and innervated: we speak of the enteric nervous system. It has the particularity of having a double innervation which will have antagonistic actions (stimulation or inhibition of digestive functions).
The digestive tract starts with the esophagus, which is about 25 cm long. It carries food to the stomach through the movements of its muscular rings. Once in the stomach, the food is reduced to a viscous mass, called chyme, which is made up of mushy food, water, mucus and gastric juices. It is in the stomach that drugs or alcohol are assimilated, unlike the rest of the nutrients, water or vitamins which will be captured further on. This chyme then passes by portion into the entrance of the duodenum thanks to the opening of the pyloric sphincter - also called the portal. Then enters the bile, produced by the liver and stored in the gallbladder, which will begin the dissolution of fats. The enzymes secreted by the pancreas will break down the lipids but also the proteins and the carbohydrates.
Note that the small intestine is between 4 and 7 meters long, which is not insignificant. Once the duodenum is passed, the following sections are progressively attacked by a stirring movement, made possible by the action of the muscles and the nervous network that surrounds them. Proteins are reduced to amino acids, lipids to fatty acids and glycerol, long carbohydrates are shortened to simple sugars. Nutrients are then absorbed, as are vitamins and minerals. Note that the small intestine is lined with microvilli. If we unfolded them completely, it would represent a surface of 40m2...
The chyme then passes into the different parts of the colon (1.5m of crossing), in which the colonic flora (composed of billions of bacteria) will continue to degrade the undigested remains. The chyme thickens and ends up in the rectum, to be evacuated.
But what explains this phenomenon? What is the relationship between sports and digestion problems?
First of all, we must distinguish between two types of digestive disorders:
- Upper digestive system (gastric) disorders: nausea and/or vomiting (up to 20%), belching (29%), reflux and heartburn (27%)
- Lower digestive system (intestinal) disorders: spasms, diarrhea (between 20 and 40%), cravings (30%).
30 to 65% of runners and triathletes (mainly, but every sport can be concerned) are confronted with this picture or have been confronted with it at least once. In 1/3 of the cases, these disorders limit the performance of the athletes. They are also responsible for more than 50% of withdrawals in long distance events.
It is important to be aware that any physical exercise requires energy for breathing, muscle function, brain function but also: digestive system! This energy comes from our food, metabolized into carbohydrates, proteins and lipids.
- During exercise, the muscles require more energy and need to be oxygenated quickly. Since we cannot increase our blood volume, we have to redistribute the cards. Digestion will then become a secondary function and lead to what is called effort ischemia. In case of an effort of an intensity corresponding to 70% of the maximum oxygen consumption (VO2max), the blood supply of the digestive tract decreases by 60 to 70%. The digestive system will be less irrigated, digestion and absorption of nutrients will be slowed down, which can lead to fatigue, diarrhea and/or vomiting, especially if the athlete has eaten a meal just before the race or after a heavy food stop. The stagnation of food in the intestine can also lead to more fermentation and therefore, bloating. Finally, ischemia can lead to or amplify the phenomenon of intestinal porosity ("leaky-gut syndrome"). The junctions between the intestinal cells will be less tight, thus allowing toxins and organisms to pass into the bloodstream, thus activating an immune response.
- Shocks to the ground (especially during running) generate shock waves throughout the body, especially in the abdominal area. The rebound of the organs coupled with these shocks can then create small lesions in the digestive mucosa, leading to bleeding, pain and/or inflammation. The position could also play a role, for example being bent over while cycling would increase the risk of disorders.
- Water and mineral (sodium, magnesium, potassium...) losses through sweat are often very important and increase with the duration and/or intensity of the effort. They are all the more notable during efforts in a hot and/or humid atmosphere but remain important in cold weather (see our article about physical effort in cold weather).
It is necessary to compensate for these losses during, but also after the effort. It is essential to take into account the risks of digestive disorders during exercise and to hydrate accordingly.
A hypertonic exercise drink (whose concentration of carbohydrates, minerals and nutrients is higher than that of blood) will be absorbed more slowly and will remain longer in the stomach. It can then cause cramps, burns and acid reflux. It may also create a water surge (as a result of the body's attempt to dilute the drink), increasing the risk of dehydration (and related consequences) and diarrhea/vomiting. A drink that is too sweet or too acidic can also cause gastric reflux. Energy drinks increase the risk of diarrhea and abdominal pain by accelerating the transit.
During a run or bike ride, we recommend an isotonic drink (whose sodium and carbohydrate concentration is close to that of blood plasma) to allow optimal absorption and avoid the inconveniences mentioned! And of course, drink a drink that is at the right temperature and not iced or too cold to avoid upsetting your intestines even more. You will find on our website our electrolyte sachets to add to water to compensate for water and electrolyte losses in an optimal way.
- A highly concentrated food intake before and/or during exercise, especially in carbohydrates (hypertonic drinks, gels, large quantities of maltodextrins, energy drinks, etc.) can also lead to nausea, diarrhea, nausea and abdominal pain (but also to hypoglycemia - see our article dedicated to hypoglycemia during sport).
- Poor chewing of food can also lead to digestive problems.
- Taking non-steroidal anti-inflammatory drugs (NSAIDs) can also cause or amplify acid reflux and the leaky-gut syndrome.
How can these problems be overcome?
- Know yourself: everyone is different and a good advice for one person may not be universal. However, this one is. It is essential to know oneself well in order to manage one's effort and sensations and thus avoid going too far. As far as food is concerned, it is advisable to test any new product during training, especially not during a competition. For example, at Holyfat, we recommend that non-keto-adapted athletes (see our article about the ketogenic diet and sports) use our pouches during their training and long outings, keeping a source of carbohydrates on hand. It can be used at the end of the run to recharge glycogen stores, or along the way if fat is not enough to provide you with sufficient energy.
- Hydrate well: as we said a few lines above, it is essential to hydrate correctly, with the right drink during and after an effort. It is recommended to drink from the start about 300 to 500ml of exercise drink (energy, not energizing) per hour, preferably hypotonic. It is recommended that you take 2-3 sips every 7 to 10 minutes of effort so as not to bring too much volume to the digestive system.
- Eat liquids: it is preferable to prefer liquids to solids during long and/or high intensity efforts, in order to limit mastication and the efforts of digestion and assimilation. It is also preferable to have a good quality/quantity ratio. At Holyfat, we have developed our products in this sense. Our small pouches bring you 280kcal on average for 40g, with a thick liquid texture: the liquid, the quality and the quantity joined together in only one product, ideal for a durable energy without slackening (since without added sugars and naturally low in carbohydrates).
- Avoid taking NSAIDs, especially around a race (before/during or after), drinking energy or hypertonic drinks and ingesting liquids that are too cold.
- If you wish to use exercise gels, note that you will need to take them every 45 minutes or so to avoid hypoglycemia. The risk of nausea is therefore present, as well as the digestive risks linked to the ingestion of a very sweet product.
- Vary the flavors to avoid saturation and disgust. At Holyfat we have developed a range of flavors that allow you to combine pleasure and performance: vanilla, cocoa-salt, cocoa-orange, cocoa-chili, ginger, coconut, coffee...
- ... With more or less pronounced tastes, you can vary your snacks and go further.
Here are some good practices to go further and further, while keeping the pleasure of the effort and avoiding some inconveniences. Of course, do not hesitate to surround yourself with qualified professionals to achieve your various performances and above all, get to know yourself and find the formulas that work best for you!
>> Do not hesitate to consult our other articles, including "How to avoid fatigue during exercise, especially during an endurance sport", as well as our focus on almonds, walnuts, cocoa, coffee or MCT oil ...
With the added bonus of some tips and advice for the preparation and your sports outings (or your busy days).