Gut Issues in Endurance Athletes
The most common issues are nausea, vomiting, and diarrhoea. The first two affect the stomach, and the latter the bowels.
Nausea & Vomiting
High-intensity exercise, especially done in hot weather, can push athletes to the limits, and for some, this includes an unwelcome experience of nausea and vomiting. Not only is it uncomfortable for the competitor, but it’s also not the grand finish line photo anyone had in mind. Many athletes struggle to digest and process food or fluids effectively during intense races, leading to gastrointestinal (GI) distress that can be draining and embarrassing.
Why Does This Happen?
Exercise-induced nausea and vomiting stem from several physiological factors, especially when exercise is long, intense, or done in high temperatures. During high-intensity efforts, blood flow is redirected to working muscles, limiting the blood available for digestion. This “gut steal” effect can slow or even stop digestion, creating an uncomfortable buildup in the stomach. High temperatures intensify this effect because your body is also busy cooling itself, drawing blood away from the stomach.
Additionally, the jostling of running or other intense activities can physically disrupt the GI tract’s contents, causing nausea, vomiting, and/or diarrhoea. Psychological stressors like pre-race anxiety or racing nerves may worsen GI symptoms, as stress hormones like cortisol can affect digestion.
Some athletes experience issues with food or fluid intake during events. Whether it’s poorly timed nutrition, an overload of simple sugars, or excessive hydration, any imbalance can add stress to the stomach, making it harder for the body to cope as intensity rises.
Symptoms and Presentations
Most athletes know the early signs of nausea all too well: that queasy, unsettled feeling that can make each step feel like a gamble. Nausea can range from mild discomfort to a sense of fullness and bloating. If exercise continues, symptoms may escalate to outright vomiting, which, while it can provide brief relief, is highly dehydrating and energy-sapping.
The timing of symptoms varies. Some experience nausea mid-race, while others endure it until they cross the finish line, only to find themselves immediately reaching for a trash can. Other common signs include dizziness, cramping, a feeling of fullness in the stomach, and, in severe cases, dry heaving.
Treatment and Prevention Options
Managing nausea and vomiting during races is possible, but it often takes trial and error to determine the right approach for each individual athlete. Here are some effective strategies:
Fine-tune Your Pre-Race Nutrition: Avoid heavy, fatty, or high-fibre foods on race day, as these can linger in the stomach and cause discomfort. Aim to finish eating at least two to three hours before high-intensity exercise. Foods that are bland, lower in fat, and easy to digest are ideal pre-race fuel.
Stay Hydrated, but Don’t Overdo It: Hydration is crucial, especially in hot weather, but overhydration can cause bloating and nausea. Balance your fluids based on race conditions and personal sweat rate. Generally, avoid “chugging” large amounts at once, and consider sipping on small amounts consistently to avoid overloading the stomach. These days, elite athletes often train their stomachs to tolerate significant amounts of fluid while racing, especially when the race finds a place in hot conditions and more than the generally recommended 600 ml per hour is required.
Pacing: While it’s tempting to go full throttle, pacing yourself—especially in the early stages of a race—can reduce the likelihood of GI upset. This strategy allows your body to adjust gradually, lowering the risk of nausea.
Adapt to the Heat: If you know you’ll be racing in high temperatures, plan for heat acclimatisation in advance. Training in warmer environments (with caution and proper hydration) can help your body adapt and reduce the chances of GI distress on race day.
Experiment with Race Nutrition: It’s important to practice your nutrition strategy during training, including the types and timing of food and fluids. Test out what works for your stomach at race intensity so you’re not experimenting on race day. For some, slower-digesting carbohydrates or electrolyte-rich fluids may be better tolerated than sugary gels or drinks.
Consider Ginger or Peppermint: Both ginger and peppermint have mild anti-nausea properties that might help settle the stomach. Ginger candies, chews, or peppermint tablets can be handy additions to your race kit if you’re prone to nausea.
Medication: For some athletes, low doses of anti-nausea medications, such as those used to treat motion sickness, may be useful. Always consult a healthcare provider before using any medications on race day to ensure they are safe for your specific needs
Experiencing nausea and vomiting during or after a race is never pleasant, but it’s often manageable with the right adjustments to nutrition, hydration, pacing, and heat preparation. By finding a strategy that works for your body, you can make it through the finish line feeling strong and steady—without an unwanted close-up of your breakfast.
Runners Diarrhoea
Runner's diarrhoea, also going by colourful nicknames I can’t print, is something most runners dread. If you’re one of the many who’s had to make a mad dash, mid-dash, to find a bathroom (or bush), you’re not alone. This frustrating and, let’s face it, embarrassing problem involves sudden, frequent, and loose bowel movements during or after a run. Fortunately, with some planning, runners diarrhoea doesn’t have to ruin your training or keep you anxiously eyeing the nearest restroom sign.
Symptoms and Presentation
Runner's diarrhoea usually involves urgent, loose stools that show up—at the worst possible moment—during or just after a run. The symptoms can vary: some runners feel the urgency after a few kilometres, while others get through their run only to develop a grumbling gut afterwards. Add in some classic features like abdominal cramps, bloating, and even a touch of nausea, and it’s hardly the post-run glow you were hoping for. While runner's diarrhoea is often just an inconvenient part of the sport, it can lead to dehydration or nutrient loss in severe cases, so it’s worth addressing if it’s impacting your training or quality of life (or scaring off running buddies).
Why Does This Happen?
Similar factors, as outlined under the stomach issues, are likely culprits. First, the repetitive jostling from running can physically “shake up” the intestines, speeding up the whole digestive process. The jostling effect is more evident in the running movement, hence the name runners' diarrhoea. It occurs less often in cyclists and swimmers. Blood flow also plays a part; during exercise, blood is diverted away from the digestive system to fuel muscles, which can cause some unpredictable GI effects.
There’s also evidence that certain foods can play an unfortunate role. High-fibre meals, caffeine, sugar, and artificial sweeteners may all increase the risk, especially if eaten too close to workout time. Then there are the food allergies and sensitivities; for example, lactose and gluten are well-known culprits.
Diagnosis and When to Seek Help
While occasional runner’s diarrhoea is common, frequent or severe cases are worth discussing with a healthcare provider. If you’re experiencing blood in the stool, significant weight loss, or other signs of gastrointestinal distress, it’s best to check for possible conditions like irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD), which may need more specific treatment.
A doctor will likely ask about your symptoms and may order some basic tests, such as blood work or a stool sample, to rule out infection. For most cases, a full battery of tests isn’t needed—especially if it’s clear that the main trigger is your running habit.
Treatment and Management Options
When it comes to managing runner’s diarrhoea, a few tweaks to your routine can go a long way:
Diet Tweaks: Before your run, try avoiding high-fibre foods, caffeine, fatty meals, and artificial sweeteners. If lactose intolerance could be at play, go easy on dairy. Keeping a food diary can be helpful.
Timing of Meals: It’s best to avoid eating large meals within two hours of your run. Instead, stick with lighter, easy-to-digest snacks if you need pre-run fuel. Remember: running on a full stomach isn’t doing you or your gut any favours.
Hydration Habits: Staying hydrated is critical, but over-hydrating can stress the gut. Practice a balanced approach to fluids, adjusting as needed, and avoid sloshing stomachs.
Take it Slow: If you’re prone to symptoms, try easing up on the pace or avoiding intense speed work until you’ve found what your stomach can handle. Over time, as you build endurance, your body will adapt.
When racing: Nothing is worse than the urge for a pitstop in a long-distance event. Slowing down is not an option; by that stage, it is unlikely to help much anyway. Giving in to the urge can cost a lot of time. Here, prevention is definitely better than cure. This involves experimenting with pre-race and race nutrition in training and taking the tips on diet tweaks into account.
Supplements: Some runners find that adding probiotics helps balance their gut flora. These can be found in foods like yoghurt or supplements, but be cautious—they’re not magic, though they might provide some support.
Medication. If a runner’s diarrhoea persists despite these strategies, medication might help. Loperamide (Imodium), taken before a run, slows bowel movement before a run or race. A lesser-known but very effective treatment is nifedipine in a low dose, like 2.5-5 mg, before a workout. Nifedipine tablets come in several different strengths, up to 60 mg, so 5 mg is a very low dose, which means there is less chance of side effects like headaches or dizziness. Nifedipine is a prescription drug mainly used for high blood pressure and angina. Not all doctors will be familiar with this indication, but it works like a treat, as I have experienced with patients
Though runner’s diarrhoea can be inconvenient, it’s usually manageable with a bit of patience and experimentation. Taking the time to understand your body’s quirks will help you find the right routine, keeping you on track to finish strong without an unplanned sprint to the nearest restroom.
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