The Core Diet Blog

“I Guess I Shouldn’t Have Eaten That”

A common complaint I hear as a sports dietitian is “I can’t eat anything before or during exercise because it causes stomach issues.”

This can be especially problematic for athletes participating in long distance triathlons and running events.  While athletes can often complete short distance triathlons without sports fuels, they will require them for long distance events.  Consumption of fuels prevents bonking and are fundamental for speed and performance.  Research indicates the athletes that consume the most calories during a race have faster race times (Pfeiffer, B et. al, 2012).  The bottom line is getting the gut adapted and efficient at digesting fuels during training sessions and races is going to positively impact speed and performance.

Frequently experienced gastrointestinal symptoms include nausea, heartburn, vomiting, diarrhea and bowel urgency.  The incidence of gut intolerance typically increases during longer duration events and are further exacerbated during races due to the heat, humidity, stress, hormone shifts, dehydration and exercising at a higher exertion level.  This can make tolerance to fuels during long distance training and races difficult.

But how do you get your gut adapted and efficient at digesting fuels during training and racing? 

Plan your meals around training times. As a general guideline, finish your last meal at least 2 hours before a bike and 2-3 hours before a run or swim.  This will provide adequate time for the meal to be digested and exit the stomach before initiation of exercise.  For example, if you are meeting friend for a run at 4pm, plan to finish lunch by 1-2 pm. 

Go with simple fuels.  There are a variety of gels, blocks, chomps and sports drinks marketed for fueling however some are easier to digest then others.  More ingredients in a fuel is not necessarily better, and many times those marketed with high levels of micronutrients can end up causing GI distress, and the consumption of fat, fiber and protein immediately before and during exercise is associated with gut intolerance issues.

Read the labels. Read labels closely and consider the ingredients in the product.  Products consumed during exercise should primarily contain carbohydrates (for example maltodextrin, fructose) and electrolytes such as sodium and potassium.  Many fuels contain herbal additives, vitamins and minerals that can be irritating to the gut.  For example, vitamin C in large doses can have a laxative effect and the sugar alcohol sorbitol can cause gas and diarrhea. 

Practice makes perfect.  I cannot emphasize enough that you need to experiment with different foods and products.  For a pre-workout fuel, choose a food that is low in fat, fiber and protein and provides around 25 grams of easy to digest carbohydrates. Options include a banana, glass of sports drink, small bag of fat free pretzels, serving of low fat animal crackers, a gel or blocks.  Avoid whole grain, high fiber and/or high fat containing foods right before a workout because they will sit in your stomach for a long period of time.  The longer food remains in your stomach, the likelier it will cause GI issues.

Practice race fueling plans during long training sessions. Many athletes don’t practice their race fueling plans and are unaware they have gut issues until the race.   This can be problematic and very disappointing.  While it is difficult to replicate race conditions, training sessions are the next best opportunity.  This will “train your gut” to efficiently digest fuels and increase gut tolerance. 

Keep a food journal.  Are you eating too much before a long workout?  Does a high fiber meal the night before a brick workout stimulate an urgent bowel movement during the run?  Are you eating too many rich, high fat foods and you are belching during a bike ride?  Writing down what you eat and the symptoms you experience may be essential to identifying the problem. 

Try and try again.  It will take time to get your gut adapted to taking nutrition during exercise.  If you try one product and it doesn’t digest well the first time, perhaps try again.  If after consecutive attempts it continues to contribute to intolerance, then try a different product.  For example, if fructose based gels are problematic, then try a product made with maltodextrin.

I can’t stress enough that practice makes perfect.  Unfortunately, the process is “trial by fire”.  If symptoms continue after trying these strategies, consider seeking the help of a professional.   A professional may be able to identify trends, intolerances, ingredients to avoid and recommend appropriate substitutions. 

~ Brooke

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