When we talk about the problems of athletes, we think first of all about their muscles, their joints, sometimes their heart. Their digestive disorders are rarely mentioned. Unknown, often taboo, these disorders remain a sensitive subject: disabled, sometimes heavy consequences, it is important to understand and prevent them.
How do digestive disorders manifest in the athlete?
Affecting in the first place endurance athletes such as marathoners, these digestive disorders are manifested by:
- Cramps and intestinal pain,
- Diarrhoea, sometimes bloody,
- Nausea, Vomiting,
- A gastroesophageal reflux,
- Difficulty eating,
- Digestive bleeding (1).
They occur during activity or immediately after, in people who had no symptoms before (2). Their prevalence is important as 37 to 70% of athletes experience them during a race or in the immediate follow-up to a competition.
More than annoying, they will force the athlete to suspend his effort and can, in the case of digestive bleeding, represent clinical emergencies.
Fatigue often associated with anemia, damage to the liver or pancreas (3) or the feeling that certain foods “do not go well” may appear.
At the forefront: reperfusion ischemia
Running impacts have long been accused of being the main cause of intestinal disorders in athletes. However, since the 1990s (4), it is known that the cause of these disorders is not only mechanical.
Our bodies, and especially our intestines, would not be entirely capable of overcoming intense and prolonged physical effort.
During exercise, free radicals are secreted in very large quantities. These molecules from the metabolism of oxygen and nitrogen by our body tend to accelerate the degenerative processes of our cells.
If our body can normally defend itself to restore balance, it must, during intense effort, face a massive influx of free radicals. In response, it releases anti-radical defenses in a very significant way... until it is almost exhausted.
In the athlete, this massive arrival of free radicals in the intestines is linked to the phenomenon of reperfusion ischemia (5). If the term is complicated, what it means is simple. During the exercise, the blood flow is made in a privileged way to the muscles (heart, legs, arm..). In return, the irrigation of blood from the intestine decreases significantly (at 70% of the VO2max, the blood flow at intestinal level is reduced by approximately 80%!). This phenomenon explains in part the cramps, diarrhoea and nausea encountered by the athlete. The fluctuation of the oxygen level at the intestinal level will induce increased radical production and thus, with repeated physical exercises, a significant degradation of bowel cells.
Intestinal hyperpermeability
This massive attack of free radicals at the tight joints of the intestine that ensure the sealing of the walls causes porosity. This is called intestinal hyperpermeability. (5). The intestine no longer fulfils its role as a "sorting station". Substances (bacteria, toxins, pollutants, additives,...) then uncontrolledly pass through the intestinal barrier. In itself, from the production of a large amount of free radicals, exercise tends to increase this phenomenon. But, when the efforts are repeated and intense, an intestinal permeability syndrome (“leaky gut syndrome”) may appear. This porosity of the mucous membranes becomes chronic, coupled with an inflammatory and pro-oxidative state that promotes the decrease of immune defenses.
This condition, common in athletes, is likely to create endotoxinosis, which means that bacterial debris will end up in the blood. This "endotoxinosis" causes discomfort, episodes of torpedo, flu states after a long run (6). In the long term, recurrent tendinitis (7), chronic pain, allergies, food intolerance, or autoimmune diseases (8) are likely to occur.
What are the aggravating factors?
A number of physiopathological factors tend to aggravate digestive disorders in the athlete (9).
Dietary Mistakes
The diet of the athlete is part of the good health of his digestive system during the exercise and beyond. A number of scales, which are based on old beliefs, are to be avoided:
- Hyperconcentration of food intake before, during and/or after exercise, especially in carbohydrates that tend to ferment.
Meals too abundant in advance of exercise, too rich in lipids and/or fiber, or taken too little time before the test. - A diet low in lipids and especially in Omega 3 which are powerful anti-radicals.
The non-compliance with an exclusion regime in case of intolerance or food sensitivities. On an inflammatory ground, the athlete will be recommended to pursue a gluten-free and/or lactose-free diet at least during the pre-competitive period. - Inadequate chewing of foods leading to mal-digestion and mal-assimilation.
The consumption of hypertensive and/or energy drinks before the race. Let’s not forget that caffeine is a stimulant that can also act as a laxative (11). Ice drinks are also forbidden. - A dehydration. Many runners start drinking too late during the race.
Taking certain medicines
Many athletes self-prescribe anti-inflammatory (AINS) before a test (10). These drugs tend to significantly increase the phenomenon of intestinal porosity and can cause gastrointestinal bleeding or even ulcers. (12). Their use for sports injuries is now widely questioned in terms of the risk/benefit balance.
What prevention?
Against the intestinal disorders encountered by athletes, the approach is primarily prophylactic: it is about acting in advance, although some dietary supplements can also play a restorative role.
Food
Diet plays a major role in preventing digestive disorders. Two elements are interesting in terms of prevention: the importance of fatty acid intake and a reasonable elimination diet.
For weight loss and/or performance concerns, many athletes exclude fat from their diet without distinction. However, fatty acids provide essential functions in terms of digestive balance (13). While they are important suppliers of energy, especially during long-term efforts, they are crucial to combat inflammation and strengthen immune defenses. This is especially true for Omega 3s, which act as powerful anti-free radicals agents and prevent or at least limit the symptoms associated with ischemia-reperfusion. (5). It is therefore important to consume regularly:
- Fatty fish (salmon, hareng, sardines, mackerel), colza oil,
- Shell fruits (nuts, almonds, walnuts...),
- Green vegetables.
A digestive-saving diet inspired by the Cretan model is a good reflection to adopt (5) and especially before a sports competition.
Then, since intestinal hyperpermeability creates intolerance or food sensitivities, the athlete will gain to know the foods that cause him discomfort. He will gain, even for a while, by excluding
them from his diet. It is not a question of blocking out all potential allergens, but of taking a reasoned approach (5).
Food Supplements
Nutrition therapy is a very valuable help to prevent digestive disorders in the athlete but also to improve the repair of the intestinal mucosa. To do this, it is recommended to adopt:
- Probiotics. Since the intestinal flora is degraded through the massive influx of free radicals due to reperfusion ischemia, it will be useful to use probiotics to rebalance it and prevent endotoxinosis.
- L-glutamine, which contributes to the restoration of intestinal permeability (16) at least 2 grams per day.
- Antioxidants that will help the body fight free radicals. Quercetin, a pigment of plant origin that belongs to the flavonoid family, is interesting because of its anti-inflammatory properties and its ability to inhibit histamine that causes many allergic reactions.
- Omega 3. If dietary intakes are insufficient, supplementing with omega 3 will help to strengthen immunity and combat inflammation.
Keep in mind that performance does not come from the legs or head but from the digestive system. It is important to take care of it!
Sources:
(1)Watelet, J. (2008). Digestive manifestations in the athlete. The Letter of the Hepato-Gastroenterologist, 5, 170-176.
(2)FOGOROS RN (1980): Gastro-intestinal disturbances in runners: “runner’s trot”. JAMA, 243: 1743-4.
(3) Watelet, J., & Bigard, Mr. A. (2005). Liver-digestive disorders of the athlete. Clinical and Biological Gastroenterology, 29(5), 522-532.
(4)BROUNS F, BECKERS E (1993): Is gut an athletic organ? Sports Med., 15 (4): 242-57
(5) Riché, D. (2004). Intestinal hyperpermeability in the athlete. Mechanisms, consequences and nutritional care. Nafas, 2(3), 17-29.
(6) BROCK-UTNE J, GAFFIN S & Coll (1988): Endotoxaemia in exhausted runners after a long-distance race. S.Afr.Med.J., 73.)
(7)CHOS D, RICHE D (2001): “Dietetics and micro-nutrition of the athlete”, Vigot Ed
(8) (4) Fasano A. Leaky gut and autoimmune diseases. Clin Rev Allergy Immunol. 2012 Feb;42(1):71-8. doi: 10.1007/s12016-011-8291-x.
(9)Gremion, G. (2011). Gastrointestinal disorders and sporting activities. Rev Med Switzerland, 7, 1525-1528.
(10)Gisolfi CV. Is the GI system built for exercise? News Physiol Sci 2000;15:114-9.
(11)Porter AM. Marathon running and the caecal slap syndrome. Br J Sports Med 1982;16:178.
(12)Ziltener, J. L., Leal, S., & Fournier, P. E. (2010). Non-steroidal anti-inflammatory drugs for athletes: an update. Annals of physical and rehabilitation medicine, 53(4), 278-288.
(13) HILLIER K, JEWELL R & Coll (1991): Incorporation of fatty acids from fish oil and olive oil into colonic mucosal lipids and effects upon eicosanoid synthesis in inflammatory bowel disease. Gut, 32: 1151-5
(14)VENAKATRAMAN JT, CHU W (1999) : Effects of dietary w3 and w6 lipids and vitamin E on proliferative response, lymphoid cell subsets, production of cytokins by spleen cells and splenic protein levels for cytokines and oncogenes in MRL/MpJ-1pr mice. J.Nutr.Biochem., 10: 582-97.
(15)GOLDIN BR (1998): Health benefits of probiotics. Brit.J.Nutr., 80 (Suppl.2): S203-S207
(16)Zuhl MN, Lanphere KR, Kravitz L, Mermier CM, Schneider S, Dokladny K, Moseley PL. Effects of oral glutamine supplementation on exercise-induced gastrointestinal permeability and tight junction protein expression. J Appl Physiol (1985). 2014 Jan 15;116(2):183-91