This week I wanted to discuss a common downfall of many endurance sport races — GI distress. There are a lot of factors that can contribute to GI distress during runs or races, many of which pertain to fueling or lack thereof. The table below goes through various possible causes of GI distress and what you can do to help prevent it in the future.
| Possible cause | Solution |
| Something you ate prior to running did you dirty | Minimize fat, fiber, and protein intake in your pre-run meal. Foods that are primarily carb-based with a hint of fat/protein tend to be more easily tolerated. E.g., white toast w/ jam, bagel w/ bit of pb, pop tarts ❤ |
| Not taking enough carbs during run | Aim for 60-90+ g carbs/hour |
| Taking gel/chew without water (which draws blood from extremities to your gut very quickly) | Carry water w/ you or stop at aid station to drink water with gels/chews. Or try carb drink mix instead of solid carbs for fuel. |
| Taking gel too quickly (for similar reason as above) | Try to spread your carb intake out over a longer period of time |
| Not drinking enough water/fluids | Aim for 12 to 24+ oz of fluids/hour |
| Not taking in enough electrolytes | Aim for 300-600+ mg sodium/hour Notes: The likelihood of OD’ing on electrolytes during a run is very low, as long as you’re taking in fluids as well. The likelihood of becoming hyponatremic (too low sodium in the blood) is much higher. If you’re heavily consuming sodium on a daily basis and start to get symptoms like bloating, puffiness under the skin and in your joints, strong sensations of thirst and a dislike of salty tastes – this would be a sign to take it easy on the salt. |
| Caffeinated fueling products | Avoid caffeinated fueling products – some people are simply more sensitive to caffeine & there’s nothing worse than having to go during your race |
| Not practicing your fueling strategy and/or carb loading during training | Practice your fueling plan during every long run and practice carb loading the day before long runs! You can “train” your GI tract to take in more fuel over time, just as you train your muscles and cardiovascular system to withstand long endurance efforts. |
| Overall under-fueling and/or under-consuming carbs can impair smooth muscle function and promote inflammation of the GI tract | Add more fuel on a daily basis, focusing on energy-dense foods with a big emphasis on carb intake. |
| Heat/humidity can increase gut permeability and overall increase stress on the body, which can result in GI distress | If you know your race is in a hot/humid location, try to acclimate throughout the training cycle w/ post-run sauna sessions. Nailing your fuel and hydration (increasing fluid/electrolyte intake) will also be key in hot/humid environments. |
| Use of medications like NSAIDs like ibuprofen and naproxen, as well as antacids and anti-diarrheal medications (can increase gut permeability, alter gut transit and absorption of nutrients, often resulting in GI symptoms) | Try to avoid using these medications close to runs and races if possible |
| Gut-brain axis (stress and anxiety can present as GI symptoms) | Develop strategies to help reduce pre-run/race anxiety, which could include: Meditation, visualization, yoga, pep talk from your dog (or family or friend), working with therapist or sports psychologist. |
If you have any questions or need help dialing in your fueling practices, feel free to reach out. Happy fueling!
Gabriella Rao, RD 
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