Battling GI Issues

Bloating and GI issues affect many runners, one studying citing that between 30-50% of runners experience lower gastrointestinal (GI) distress during long or intense runs, including diarrhea, a sudden urge to defecate, and abdominal cramping. GI issues can make training and racing unenjoyable and extremely uncomfortable. However, this isn't something you should have to live with as a runner. There are many things that can be adjusted that may help give you relief. 


There is no one way to stop or prevent GI distress because not any one solution works for everyone. We are all built differently and respond differently to food, hydration, and training. Here are a few ways you may be able to decrease your GI distress:


  • Modify & Monitor Your Diet

  • Establish a Routine

  • Stay Hydrated

  • Replenish Carbohydrates & Electrolytes

  • Avoid Drugs

  • Avoid Sweetened Foods and Fructose Drinks

  • Track Your Menstrual Cycle

  • Work with a Registered Dietitian or Nutrition Coach


Modify and Monitor Your Diet

Most runners find that GI issues are diet related. Avoid foods higher in fiber and fat in the days before a race, instead eat naturally constipating foods such as white pasta, white rice, etc. To determine which foods affect you most keep a journal of the foods you consume and your bowel movements. 

It can take anywhere from 24 to 72 hours for food to travel through our system, with runners tending to be on the faster side. Whatever you do, don’t stop eating during your marathon and long training runs - your body needs that fuel! 


Establish A Routine

Your body likes to create a state of balance, when a routine changes it can have huge impacts on how we feel and perform. One thing to avoid is introducing new foods and/or drinks on and near race day. If you are planning to use fluids and/or gels, granola bars, etc. during your race it is extremely important to introduce those things during training to get your body used to them, as well as to see how your body reacts. If you have a morning race, I’d recommend creating and practicing a race day routine and trying to get your runs in around the time your race will start so that your body is more likely to be optimally prepared come race day. 


Stay Hydrated 

Losing 4% of your body weight in sweat during a run/race increases your risk of diarrhea while running. This means the fluids you drink may help prevent that. Diarrhea has a high water content, making it a cause of dehydration. Ensure you take in fluids before, during, and after exercising.

Here are some core hydration practices to help avoid dehydration:

  • Follow basic guidelines for drinking water throughout the day:

  • For every kg of bodyweight, ingest 30-40mL of water.

  • If you weigh 50kg (110lb) you’d need 1.5-2L (51-68oz) of water per day.

  • If you weigh 100kg (220lb), you’d need 3-4L (101-135oz) of water per day.

  • Hydration for exercise: 

  • Drink 0.5-1L (1-4 cups) of water per hour of physical activity. 

  • For recreational exercisers who have mastered basic hydration strategies and want a little extra recovery boost, it is recommended to add 15-25 grams of protein from protein powder during workouts. If whole protein is not tolerated, add 10-15g of essential amino acids (EAAs), or less ideally, add 10-15g of branched-chain amino acids (BCAAs) during your workout. 

  • Drink 0.5-1L (1-4 cups) of water in the hour or so afterwards. 


Replenish Carbohydrates & Electrolytes

If we are sweating a lot then we are not only losing water but also electrolytes that help keep us performing optimally. Over consuming fluids without replenishing electrolytes can throw off the fluid balance in your body and have a wide range of unwanted symptoms as a result. However, we don’t need to be overzealous! A diluted carbohydrate drink that also contains electrolytes is ideal for maintaining electrolyte balance and optimal performance according to Precision Nutrition. Taking in carbohydrates during and after exercise can:

  • Improve how quickly fluid is absorbed

  • Enhance endurance

  • Lower the stress response and inflammatory damage of training

  • Improve immunity

  • Enhance whole body hydration; and

  • Improve muscle and liver glycogen synthesis 


However, this drink should be dilute, ideally less than 10% concentration. More concentrated solutions will not only absorb slowly they’ll likely cause GI upset. You can also add the above recommended protein to this drink.


Avoid Drugs

Runners often turn to medication or procedures to remain accident free on the run. Trying to flush everything out can be risky. Runners who purge their intestines with chemical laxatives, enemas, bowel preps, and colonic irrigations can cause altered electrolyte levels and have major side effects, including nausea and stomach cramping. 


Taking ibuprofen before a race to head off any possibility of pain is a bad idea for a number of reasons. The common use of anti-inflammatory drugs such as NSAIDs can aggravate gastrointestinal (GI) bleeding, and potentially cause leaky gut. This can allow for bacteria to enter your system and interfere with fluid balance at the level of your kidneys, making it easier to get dehydrated. It has also been shown to interfere with recovery. 


Instead try to eat a few peppermint Tums (calcium carbonate) about 20 minutes before heading out the door. Keep peppermint Tums handy during higher intensity workouts and long runs to help slow down any GI issues. Other products such as Alive and Goodgut have been shown to maintain the lining of the gut and they work especially well when the gut is stressed from increased body heat and low oxygen/low blood circulation during exercise. Dr. Stacy Sims recommends using this each morning of taper week to help improve gut integrity. 


Avoid Sweetened Foods & Fructose Drinks

It’s important to consider what kind of fluids and fuels you are consuming as well. While some sports drinks are beneficial for preventing dehydration, not all sports drinks are created equal and sex plays a role in which type of sports drink is going to give you the most benefit. 


According to Dr. Stacy Sims, most sports drinks don’t offer women the same benefits that they offer men. Many sports drinks are high in fructose and women have less of a fructose transport gate, making it harder to digest and harder on the gut. Dr. Sims states that per 100g of fructose, men can absorb 66g of fructose, while women can only absorb 26g. This is something to be aware of when choosing fueling options as well as some gels have higher concentrations of fructose than others. 


Track Your Menstrual Cycle

If you have a menstrual cycle, or are in perimenopause or menopause, tracking your symptoms and  incorporating a pre training or race plan to mitigate bloating and other symptoms is crucial to athletic performance. As hormone levels change throughout a cycle and throughout women’s lives it is important to make dietary and training adjustments to optimize performance and overall health. Here’s a more in depth look at how your menstrual cycle affects GI issues and what you can do about it, here!


Work with a Registered Dietitian or Nutrition Coach

If you are having regular GI issues and not much seems to be helping, I recommend seeing your primary care physician and looking into working with a Nutrition Specialist who can help you navigate what to do next.


At the end of the day what helps mitigate GI issues is going to come down to what works for you as an individual, as there is no one way that works for everyone. I hope some of these suggestions are useful and bring you less GI discomfort in the future.


Happy Training!



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