If you don’t drink fluid regularly despite feeling thirsty, you may experience dehydration – especially during a long run on a hot day. This increases the likelihood of stomach upset, which could happen either during or after the run. Many athletes under hydrate and under fuel at the beginning of a long run or ride, and then try to adjust later or afterward – causing cramps or diarrhea. Pay attention to your thirst and hydrate regularly.
2) Are you popping sugar free gum?
Sugar-free gum contains sugar alcohols, which can pull water into the intestinal tract. This, combined with the fact that exercise speeds up movement through the digestive system, can lead to diarrhea. I’d recommend skipping the gum all together, but if you must chew something, I’d go with a regular sugar based gum.
3) Does your sports drink or fuel choice contain protein?
While protein is certainly needed in everyday nutrition and during recovery, it is not necessary in fuel choices for endurance athletes doing moderate distance/time events. Protein can cause stomach cramping and upset since it slows digestion and causes you to feel fuller longer. Ultra endurance athletes may find some choices that contain a little protein useful, as it can help with the hunger that’s experienced during these long events. It may also help prevent muscular breakdown in these events, though recovery protein likely targets this just fine.
4) Is it the first time you’re adding fuel to your long runs/rides?
If you’re a new athlete and are just delving into longer session training, you may find that you experience stomach upset when you start fueling. This is common. Just like you have to train your muscles to become strong and power you through those workouts, you also have to train your gut to process fuel while you’re exercising. For exercise over 75 minutes, I recommend 30-60 grams of carbohydrate per hour. If you’re new to fueling, start at the lower end of this range and work your way toward what’s comfortable and what provides energy to support your training.
5) Did you try a new food or product?
Hopefully it’s not race day, because you know I’d never recommend something new on race day. If you’re trying out new foods or drinks during your training – which is recommended to find what works for you! – keep a log (we have one available on our website – check out the box on the top right to grab your copy) noting your fuel choice, amount, and any GI symptoms. Regularly reviewing your log may indicate that certain foods or beverages tend to settle more poorly in your stomach compared to others. For example, gels do not sit well with me – but sports drinks and dried fruit are generally fine. Experiment to find what works for you, and use that on race day.
6) Did you go high fiber for your pre-exercise meal?
While fiber is super important to help keep you full and keep your digestive system in tip top shape on an everyday basis, it’s not ideal in high amounts in a pre-exercise meal. It increases movement through the digestive system and bulks up stool, making it more likely that you’ll risk diarrhea while exercising. Different people can tolerate different amounts of fiber, so you’ll need to figure out what works for you. For example, if you are experiencing GI upset and typically eat a high fiber cereal before your workout, try switching to a lower fiber option like Rice Krispies or Corn Flakes.
7) If all else fails, or if it feels serious, go to the doctor.
If you’ve already ruled out the causes above, you may want to visit a doctor to rule out something more serious. You could struggle with irritable bowel syndrome, a food sensitivity, or (in rare cases) something more serious. One of my amazing clients, Jess, was training for the PMC this year. We were going through her fueling plan and troubleshooting small items, yet she was still experiencing some GI upset after occasional workouts. She went to the doctor and found out she had a twisted small intestine (Jess gave me full permission to share this with you guys - read the full details on her blog, Little Miss Runshine). Moral of the story – if it doesn't feel right, and you feel like you’re doing everything right on an exercise/nutrition standpoint – visit the doctor.