In sport (and especially endurance sports), digestive problems often occur, affecting between 30 and 50% of athletes (runners are at the top of the list). The priority is to analyse the origin of these gastric problems before you start changing anything in your diet. Here are some recommendations for optimising your digestive system.


Several phenomenons can explain why digestive problems occur so frequently:

●      Digestive ischaemia, which is a lack of oxygen in the digestive tract. This is due to the redistribution of blood in the muscles (higher requirements when you exercise).

●      Eating too late. This means that gastric emptying won't have finished before you exercise.

●      Eating unsuitable food before you exercise (too many carbohydrates in your diet resulting in intestinal fermentation, or your last meal being too rich in proteins and/or fats making it harder to digest).

●      Unsuitable nutrition while you exercise (drinks that are too concentrated (hypertonic), food that is too cold, drinks that are too generous).

●      Dehydration.

●      Taking aspirin or anti-inflammatory medicines before or during exercise will increase the risk of digestive trouble by five.

It's also important to note that dietary fibres regulate intestinal transit, but be careful not to overdo it, or you may have to face the consequences of the opposite effect to the one you were looking for!

Remember to replace refined food (white pasta, white rice, white bread etc.) with whole-wheat food from time to time, and think about increasing your ratio of ripe vegetables and/or fruit and reducing the other elements of your meal (carbohydrates and protein). This will help improve your intestinal transit.


Even if you take all these precautions before you start exercising, you may sometimes find that intestinal discomfort catches up with you regardless. Your nutrition during exercise may end up being your worst enemy if you don't choose it carefully.

           -     Avoid drinking water that is too cold, because this can provoke a sudden acceleration in intestinal transit and an acute bout of diarrhoea. 15°C is thought to be the ideal temperature for staying hydrated with no side effects.

           -     If you use a sports drink during exercise, make sure you dose it correctly. It's really important to make sure it isn't hypertonic: use the proportions indicated by the manufacturer if the weather is cold to mild, and dilute slightly more when it's hot. As for energy drinks (which are completely different to sports drinks), you should never drink them while doing sport if you want to avoid gastric issues.

           -     Finally, you should check your diet regularly: this is because a diet that is tolerated well by some athletes' digestive systems may not suit you, and vice versa.There can be huge differences between two different athletes, especially when it comes to gluten or lactose intolerances during intense or prolonged exercise (this can differ from everyday life).


Of course, prevention is always better than cure, and your priority should be to find out why gastric problems occur (offending food, the circumstances in which these gastric problems are more likely to happen…) in order to avoid unpleasant side effects of a sports activity that was supposed to be fun!



As a sports enthusiast since forever and a triathlete for five years, I'm at my best when doing long distances (marathons, Ironman® etc.). I'm quite proud to have finished as the first-place Frenchman during the Ironman 70.3 World Championship in September 2017 in the US. Besides working for Decathlon, I'm also a nutritionist. I work with numerous sports users to help them with their meal planning and nutrition. Physical activity and good nutrition? Two (very good) solutions to stay fit!


We strongly advise athletes wishing to complete their training programme, or to simply play a match or attend trials under the best conditions, to follow the different nutritional strategies aiming to minimise water, mineral and energy loss after exercise.
Any physical effort involves energy expenditure that must be counterbalanced. Energy gels are composed of nutrients and micro-nutrients to satisfy the needs generated by effort. The goal is to delay the exhaustion of energy reserves and thus delay fatigue during effort.
The objective of these drinks is to replace the water, carbs and minerals lost during physical exercise. Their composition is suited to the nutritional needs of sportsmen and women during their physical activities.
Eating properly before and during exercise is all very well, but correctly managing your recovery is even better! Often ignored, the recovery stage in fact plays an essential role in rehydrating, restocking your energy reserves and muscle recovery. It also aims to get rid of lactic acid.